Military

Chapter 13

Deck Maintenance

Vessel maintenance includes inspecting, cleaning, servicing, preserving, lubricating, and adjusting (as required). It can also require minor parts replacement within the capability of the crew. As a watercraft operator, you must take an active part in keeping your vessel at its peak operating condition. This is not an easy or simple task because you are constantly battling against the corrosive effects of salt water and salt air. The wind and sea also subject a vessel and its engines to strong stresses and strains. It takes day-by-day work and watchfulness to cope with all of these conditions. Maintenance never ceases. This chapter covers the procedures and tools to be used for preventive maintenance and the required maintenance aboard ship. It should be used as a guide for all watercraft personnel responsible for shipboard maintenance.

PREVENTIVE MAINTENANCE

  13-1. These are the routine daily tasks that must be done aboard ship to prevent, or at least to hold back, the formation of rust or deterioration of the ship's equipment. The first and most important step in proper maintenance is to keep a vessel clean. This is necessary to good health and efficient operation.
DECKS
  13-2. Wash and scrub decks often to prevent tracking dirt throughout the vessel. If it can be obtained, canvas or cocoa matting can be laid on the deck wherever people walk. Scuppers must be kept clean and open so water can flow overboard freely and not leak into spaces below.
TOPSIDES
  13-3. Topsides and superstructure must be washed often, using fresh water when possible. A small amount of washing soda can be added to the wash water to help in the cleaning. Parts washed with soda and water must be given a final washdown with fresh water, if possible, or salt water.
INTERIOR
  13-4. See that quarters are cleaned daily, giving close attention to dark corners and spaces blocked by lockers and other furnishings. Dirt collecting in these spaces results in unsanitary conditions where vermin can breed and rot can develop.
BILGES
  13-5. The rounded parts of a vessel's bottom, known as the bilges, collect water, oil, fuel, trash, and so on. Keep them clean and well aired because dirty bilges are a fire hazard, produce disagreeable odors, and are harmful to vessels.
CARGO HOLDS
  13-6. Keep cargo holds clean. Stow and secure excess dunnage. Trace and eliminate sources of fumes and odors.

HAND TOOLS AND THEIR USE

  13-7. These tools must be cared for and used properly to get the most use from them. Safety in their use must also be stressed at all times.
HAND TOOLS
  13-8. The following are the most commonly used hand tools found aboard ship:
 
  • Chipping hammer.
  • Wire brush.
  • Hand scrapers.
  • Portable electric grinder.
  • Sandpaper.
  The use of each of these tools is described below.
Chipping Hammer
  13-9. Before letting anyone use this hammer, make sure they have been instructed on how to use only enough force to remove the paint. If a great deal of force is required to remove paint, the paint is still good and should not be chipped off. Feather the edges and paint.
Wire Brush
  13-10. This is a handy tool for light work on rust or on light coats of paint. It is also used for brushing around weld spots. When the surface is pitted, use a steel wire brush to clean out the pits.
Hand Scrapers
  13-11. These are more useful for removing rust and paint from small areas and from plating less than one-fourth inch thick, where it is impractical or impossible to use power tools.
Sandpaper
  13-12. Sandpaper can be divided into two types of abrasive materials: natural and artificial. The flint and garnet grits of ordinary sandpaper are natural abrasives. Emery and corundum are also used in the production of some of the cheaper grades of abrasive sheets. Artificial abrasives have largely replaced natural abrasives for use on metal. The two principal artificial abrasives are silicon carbide and aluminum oxide.
  13-13. The size of abrasive particles is indicated by code numbers ranging from 4 to 5/0 (or 00000). In garnet and artificial abrasives, 4 or 3 would be a very coarse abrasive (16-24 mesh); 2 1/2 to 1 1/2 would be coarse (30-40 mesh); 1 to 0 would be medium (50-80 mesh); and 2/0 to 5/0 would be fine (100-180 mesh). In flint paper or emery cloth, 3 to 1 would be coarse; 1 1/2 to 1/2 would be medium; and 0 to 3/0 would be fine. You will find sandpaper indispensable in cleaning corners. The usual procedure is to go over the surface first with a coarse sandpaper and polish it with one of the fine grades. Do not polish any more than final finish requirements dictate, however, as paint bonds best to clean surfaces which are rough enough to provide "mechanical tooth."
  13-14. There is also a waterproof type of sandpaper. This usually consists of a better grade of garnet grit, bonded (made to stick on the paper) with a special resin. These sheets may then be used with water or oil for wet sanding. Ordinary sandpaper will disintegrate when used with liquids.
SHARPENING SCRAPERS AND CHIPPING HAMMERS
  13-15. Like other tools, scrapers and chipping hammers gives the best service when they are kept in good condition. Normally, this involves little more than sharpening the scrapers and hammers.
  13-16. The first step in sharpening a scraper is to square the end. Adjust the tool rest of the grinder so that it just clears the face of the wheel (see Figure 13-1 [views 1 and 2]). First, lay the scraper flat on the rest. Then, keeping the end of the scraper parallel with the shaft of the grinder, move the scraper back and forth across the face of the wheel. Grind across the entire width of the scraper. Use enough pressure to keep the wheel cutting out but not enough pressure to decrease its speed or overheat the metal. Keep a can of water handy while grinding and dip the scraper frequently into the water (this helps to prevent the scraper from overheating and drawing the temper from the metal). If the scraper has been chipped, grind away the edge until the chips disappear.
  13-17. With the end squared, begin to sharpen the scraper. Hold it in such a way that the original bevel lies flat against the face of the wheel (Figure 13-1, view 3). If the construction of the tool rest is such as to support it, hold your forefinger against the tool rest to serve as a guide as you pass the scraper back and forth across the wheel (Figure 13-1, view 4).
  13-18. Sharpening any tool in this manner causes the sharp edge to curl back or feather. The last step in sharpening is to remove the feathered edge. This may be done by lightly touching the flat side of the scraper to the side of the wheel, but a better method is to remove the feather with a file that has a fine surface.


Figure 13-1. Sharpening the Scraper

  13-19. A chipping hammer is not sharpened like a cutting tool but rather like the blade of an ice skate. First square the edge as described for scrapers. Then, as shown in Figure 13-2, grind away alternately on both bevels until the squared face is from one-sixteenth to one-eighth inch wide.


Figure 13-2. Sharpening a Chipping Hammer

POWER TOOLS
  13-20. The most useful power tool for surface preparation is the portable grinder (Figure 13-3). This usually comes equipped with a grinding wheel. This brush can be replaced with either the rotary wheel wire brush or the rotary cup wire brush. Light-duty brushes are made of crimped wire and heavy-duty brushes are made of tufts of wire formed by twisting together several strands of wire.
  13-21. Scaling may be done by either of the tools shown in Figure 13-4. A chisel about 8 inches long and 1 1/4 inches wide is used with the pneumatic hammer. The hammer is held so that the chisel strikes the surface at an angle of about 45 degrees. Great care must be taken not to dent the surface. Denting forms low and high areas. This can lead to early failure of the thin paint film deposited on the high points.
  13-22. The rotary scaling and chipping tool, sometimes called a "jitterbug," is electrically powered and has a bundle of cutters or chippers mounted on either side. Use it by pushing it along the surface to be scaled and letting the rotating chippers do the work. Replacement bundles of cutters are available. Also available is a larger, heavier model of this tool, designed especially for scaling deck.
  13-23. The electric disk sander is also a handy tool for surface preparation. Great care must be taken when using this machine. The disk should be moved smoothly and lightly over the surface. It should never be allowed to stay in one place too long because it will cut into the metal or wood.


Figure 13-3. Electric Portable Grinder
and Wire Brushes

Figure 13-4. Power Scaling Tools

SAFETY PRECAUTIONS
  13-24. Most electric tools are powered by 115-volt motors. Many people tend to regard 115 volts as not worthy of even moderate precautions. But make no mistake about it, 115 VOLTS CAN AND DOES KILL!
  13-25. All electric power tools are of the three-wire, grounded type. However, the operator can still receive a shock if the insulation on the wires becomes defective due to age, abrasion, or defective repairs; the ground circuit is not complete; or the operator becomes grounded.
  WARNING: NEVER ALLOW ANYONE TO OPERATE A POWER TOOL THAT IS NOT FUNCTIONING PROPERLY.
  13-26. Always make sure that personnel wear goggles when using power tools. This is particularly important with wire brushes because strands of wire frequently break off and shoot through the air like tiny arrows, which can penetrate a person's skin with ease.
  13-27. Insist that personnel give their full attention to the job and keep all parts of their bodies away from the working end of the tools. Keep nonessential personnel out of the area where power tools are in use. Always supervise work from behind the operators.

PAINTING

  13-28. Paint is used primarily for preserving surfaces. It seals the pores of steel and helps to keep rust from forming. Paint also serves a variety of other purposes. It is valuable as an aid to cleanliness and sanitation because of its antiseptic properties and smooth, washable surface. Paint is also used to reflect, absorb, or redistribute light. For example, light-colored paint is used for the interior of the ship to distribute natural and artificial light to the best advantage. These same properties of reflection and absorption, incidentally, make camouflage painting possible.
COMPOSITION OF PAINT
  13-29. Paint consists of four essential ingredients: pigment, vehicle, drier, and thinner. To make any paint, the pigment is ground into the vehicle and the drier is added. Thinner is then added to make the paint the proper consistency for use by brush, roller, or spray gun.
Pigment
  13-30. The oldest of the opaque white pigments is white lead. White lead is no longer used in Army paint, although it is found in some commercial paints. It is made from acetic acid, carbon dioxide, and lead metal. The metal is corroded by the action of the other two ingredients until it becomes a fine, white powder. Linseed oil is usually added to this white lead to make a fine paste. It is then ready for use by the painter.
  13-31. Another white pigment is zinc oxide. Zinc oxide, by itself, makes a film that is too hard and brittle to withstand the extreme changes of outdoor temperatures, which cause it to crack and scale off. Therefore, because of its very fine texture it is usually mixed with titanium dioxide and other pigments for exterior work.
  13-32. Titanium dioxide and zinc oxide are now the principal white pigments in paints. Titanium dioxide is a white pigment with the highest known hiding power. Both titanium dioxide and zinc oxide are also considered "strengthening pigments" because they help increase the lasting quality of the paint in which they are used.
  13-33. Paint extenders, or inert pigments, are chemically stable and do not affect the color or durability of the vehicle. Extenders are used to:
 
  • Provide a less expensive base for certain kinds of colors.
  • Decrease the amount of chemically active pigments in the paint.
  • Reinforce the paint film.
  • Limit spreading power and increase the thickness of the paint film.
  • Make a good primer coat base for the finish coat.
  • Help prevent settling or caking in the container.
  Some of the more important extenders in common use are barium sulfate, calcium carbonate, whiting magnesium silicate or talc, and silica.
Vehicle
  13-34. The vehicle, usually referred to as the base, is the liquid portion of a paint which acts as a binder and brushing medium for the pigment particles. It wets the surface to be painted, penetrating the pores and ensuring the adhesion of the film formed by the drying vehicle.
  13-35. Until recently the base of most paints was an oil (such as linseed oil). Today few paints contain raw oils of any kind. Some have bases of processed oils in combination with synthetic resins; others have vinyl bases. Some fire-retardant paints have chlorinated alkyd bases; some high-performance paints have two-component epoxy or urethane bases. There are some that have water bases. Most oil-base vehicles dry partially by evaporation, partially by oxidation, and partially by polymerization. Polymerization is a process where two or more similar molecules combine chemically to form a larger molecule of a new substance. Older paints contained raw oils, had poorer physical properties when dry, and dried much slower than modern paints. For these reasons raw oils should never be added to paint. If the paint is thick and needs to be thinned, add some of the recommended thinner. Never add diesel oil, varnish, or other materials.
Drier
  13-36. Certain metallic compounds, when mixed with oil, add to the drying properties of paint. These are called driers. A paint drier acts as a conveyor of oxygen, taking it from the air and adding it to the oil. This speeds the oxidation of the paint. Without the drier, absorption of oxygen would be too slow a process, and you would have to wait too long for the paint to dry.
Thinners
  13-37. Thinners reduce the consistency of the paint to the proper degree for application by spraying or brushing. They also increase the penetration of the paint into the surface and reduces gloss. The vehicle will become diluted if too much thinner is used. As you will remember, the vehicle is the binder. So if it is diluted too much, the durability of the paint will be affected. In flat paints the proportion of oil to thinner is deliberately reduced so that the paint dries without gloss. The most common type of thinner is mineral spirits, but the proper type to use depends on the base of the paint.
MIXING PRECAUTIONS
  13-38. Most paints you will be using will be ready-mixed. That is, when you draw them from the paint locker, they are ready for use. These paints have been carefully prepared to produce coatings that will be most satisfactory under the conditions in which the paints will be used.
  13-39. Certain paints require mixing immediately before use. These are zinc-dust, water-tank paint, aluminum paint, and high-performance epoxy or urethane hull, tank, or nonskid deck paints (which contain more than one component). If the zinc-dust or aluminum paints were mixed and then stored, the heavier particles would settle to the bottom. The zinc-dust or aluminum paste should be added in exactly the quantity needed, and the paints should be stirred often during use. Multi-component epoxy or urethane paints have a limited "pot life" after mixing and will thicken or harden if not used within that time.
  13-40. Aluminum and zinc-dust paints should always be freshly mixed just before use. If they are left standing any length of time after mixing, they lose the property of leafing. Leafing is the ability of the pigment to rise to the surface of the vehicle. In all cases, these paints should be used the same day as prepared. When kept in a sealed container, they have a tendency to become gaseous. The gases could rupture containers or blow the top off the can (presenting a danger to personnel). It could also result in a fire hazard as well as loss of the paint. So mix aluminum paint and zinc-dust paint only as needed, and use right away.
TYPES OF PAINT
  13-41. There are many different kinds of paint. For example, you cannot use the same type of paint on the deck topside and on the bulkheads in the captain's cabin. There is a different paint made for almost every purpose. The following describes some of the most important paints.
Primers
  13-42. Primers are paints specially prepared to adhere well to the surfaces for which they are mixed. A primer coat provides a good base for the finish coats of paint and, in the case of metal primers, includes chemicals that inhibit (hold in check) rust and other corrosion.
  13-43. Two common primers used are red lead and zinc chromate. Red lead is a general purpose primer used on all metals except aluminum. Use zinc chromate on aluminum.
  13-44. Always apply two primer coats on exterior, topside metal that has been stripped bare. Apply a third coat of the proper primer to the outside corners and edges. Allow at least 8 hours of drying time between coats.
Exterior Topside Paints
  13-45. Properly primed, vertical surfaces above the upper limit of the boot topping area are painted with two coats of gray. In general, horizontal steel surfaces are painted with two coats of deck gray. Refer to TB 43-0144, "Painting of Watercraft," for the exact color for each surface.
Bottom Paints
  13-46. Special paints have been developed for painting a ship's bottom. Because it is continuously underwater, the bottom is exposed to two dangers (corrosion and fouling). Either of these dangers could shorten the life of the ship if left unchecked. The part of the steel hull below the waterline would rust quickly from salt water if left unprotected. The steel hull could also become fouled with various types of marine growth. Two paint coverings that help overcome these problems are anticorrosive bottom paint and antifouling bottom paint.
Anticorrosive Paints
  13-47. These types of paint do not protect against fouling. Anticorrosive and antifouling paints are always used together on underwater hulls of active ships. The anticorrosive always goes on first.
  13-48. Vinyl and Formula 14N anticorrosive paints dry very quickly because the vehicles used evaporates rapidly. Because of this, you must apply anticorrosive with short, quick strokes and progress steadily over the area you are painting. Anticorrosive paint also contains heavy pigments that settle quickly. Because the beneficial effect of the paint depends largely on these pigments, you must stir the paint frequently.
Antifouling Paints
  13-49. These types of paint will prevent the fouling of the ship's bottom that results in loss of speed and increased fuel consumption. It contains copper oxide, the chemical most effective in preventing the attachment and development of marine growth. Remember that antifouling goes over an anticorrosive. It should not come in contact with the steel plating of the ship because it may pit the surface. Be sure that the total thickness and required coats of anticorrosive paint have been applied before putting on antifouling paint.
Deck Paints
  13-50. These types of paint are fairly standard. They do differ in color according to the compartment. For example, there is a dark green (interior), deck paint for decks in quarters and messrooms, a gray deck for decks in most other living and working spaces, and a dark red deck for machinery spaces and workshops. Exterior steel decks and other horizontal surfaces may be covered in several ways. One system requires two coats of red-lead-primer formula and two coats of exterior, gray deck paint. Where nonskid surfaces are required, nonskid decking material may be substituted.
Machinery Paints
  13-51. The usual coating for the parts of machines (which may be painted) is a gray enamel called Formula 111. When painting machinery, it is important to know what not to paint. DO NOT paint the following:
 
  • Start-stop mechanisms of electrical safety devices and control switchboards on machinery.
  • Bell pulls, sheaves, annunciator chains, and other mechanical communication devices.
  • Exposed composition metal parts of any machinery.
  • Identification plates.
  • Joint faces of gaskets and packing surfaces.
  • Lubricating gear, such as oil holes, oil or greasecups, zerk fittings, lubricators, and surfaces in contact with lubricating oil.
  • Lubricating oil reservoirs.
  • Machined metal surfaces of reciprocating engines or pumps.
  • Rods, gears, universal joints, and couplings of valve operating gear.
  • Ground plates.
  • Springs.
  • Strainers.
  • Threaded parts.
  • Zinc.
  • Working surfaces.
  • Hose and applicator nozzles.
  • Knife edges, rubber gaskets, dogs, drop bolts, wedges, and operating gear of watertight doors, hatches, and scuttles.
  • Electrical contact points and insulators.
  • Internal surfaces of ventilation ducts.
  A special heat-resistant paint is available for application on objects that are subjected to high temperatures.
Aluminum Paints
  13-52. These types of paint are composed of aluminum powder or paste and a varnish specially made for mixing purposes. The standard for practically all uses is 2 pounds of aluminum powder to 1 gallon of mixing varnish. Add the varnish gradually, increasing portions and stirring vigorously until a uniform mixture is obtained.
PAINT REMOVERS
  13-53. There are three types of paint removers in general use:
 
  • Flammable. Solvent type containing benzol, acetone, and amyl acetate.
  • Nonflammable. Containing chlorinated hydrocarbons.
  • Waterbase. Alkali type containing caustic materials.
  Although all three are effective, their use aboard ship is limited because they are definitely hazardous. They must be used only in well-ventilated spaces, and all safety precautions, according to the type of remover in use, must be observed. Removers made to strip epoxy paints are extremely hazardous from both toxicity and skin-burning standpoints. Alkali paint removers must not be used on aluminum or galvanized surfaces.
  13-54. Do the following regardless of the type of paint remover you use. Wet the surface with a smooth coat of the remover and let it soak in thoroughly until all paint or varnish is loosened. Then lift the paint off with a hand scraper.
  13-55. Soon after the remover is spread on the object, a film forms on the surface of the remover. Do not disturb or break this film until you are ready to lift off the paint. If you break the film, the remover will lose some of its effectiveness. After the surface is cleaned, wet it again with the remover and wipe it off with a rag. Then thoroughly wash the surface, with paint thinner or soap and water.
 

WARNINGS:

NEVER USE PAINT REMOVERS AROUND AN OPEN FLAME BECAUSE SOME OF THEM CONTAIN FLAMMABLE INGREDIENTS. DO NOT USE THEM IN CONFINED SPACES SINCE SOME OF THEM HAVE DANGEROUS ANESTHETIC PROPERTIES. DO NOT USE PAINT AND VARNISH REMOVERS IF YOU HAVE OPEN CUTS OR SORES ON YOUR HANDS (UNLESS YOU ARE WEARING RUBBER GLOVES). AVOID LETTING THE REMOVER TOUCH YOUR SKIN (WATCH OUT PARTICULARLY FOR YOUR FACE, EYES, AND MOUTH). IF PAINT REMOVER TOUCHES THE SKIN AND BEGINS TO BURN, WASH IT OFF WITH COLD WATER IMMEDIATELY AND GET MEDICAL ASSISTANCE.

NEVER USE TURPENTINE, SPIRITS, OR OTHER THINNERS FOR CLEANING YOUR HANDS; THEY CAN BE ABSORBED THROUGH THE SKIN. GASOLINE IS ALSO DANGEROUS BECAUSE IT MAY CONTAIN LEAD. USE HAND SOAP AND WATER OR A COMMERCIAL HAND CLEANER. STUBBORN PAINT SPOTS USUALLY CAN BE REMOVED BY RUBBING WITH PETROLEUM JELLY. A LUBRICATING OIL OR DIESEL OIL CAN BE USED IF, IMMEDIATELY AFTER USE, YOU WASH YOUR HANDS THOROUGHLY WITH SOAP AND WATER.
PREPARATION OF METALLIC SURFACES (EXCEPT ALUMINUM AND GALVANIZED STEEL)
  13-56. Where sandblasting methods are not practicable, manual methods may be used. The surface should be roughened first with roughing tools such as chipping hammers and scrapers. Care must be taken to prevent nicking, denting, or scratching of the surface when using these tools. Nicks, dents, and scratches provide ideal starting points for early failure of paint films. The low portion of such surface irregularities is difficult to clean and becomes a source of rust. On the sharp-edged, high points, only a thin film of paint will adhere causing early paint failure. Chipping hammers should never have a chisel-sharp edge. Thin plate (under three-sixteenth inch) should never be chipped, but should be scraped and wire brushed.
  13-57. When the bulk of rust and old paint has been removed by roughing tools, finishing tools shall be used to complete the job. The main finishing tools are hand wire brushes, electric and pneumatic wire brushes, and sandpaper. The use of finishing tools without first using roughing tools results in a small amount of surface readied for painting or, with power wirebrushing, the "glazing" rather than removal of the rust and old paint. The hand scraper is used on small jobs, where power tools are impractical, and in crevices and corners. The hand wire brush is a useful tool for light rust and for brushing around welds and in places not accessible to the power wire brush. Sandpaper and sanding discs are used where a smooth, clean surface is desired. Where old paint is removed in spots, the edge of the remaining paint film should be sanded so that it tapers (feathers) down to the bare metal. This will give a smooth appearance to the new paint film. Steel wool should not be used as a substitute for sandpaper. Small steel particles can become embedded in the paint and form a source of rust. After the finishing operation is completed, sweep the surface to remove paint chips, dirt, and dust, and apply a liberal coat of primer.
PREPARATION OF ALUMINUM SURFACES
  13-58. Sandblasting and wire-brushing aluminum surfaces are not recommended. Clean by brushing off dirt and dust and washing the surface with paint thinner. Then, wash with paint cleaner and water (soogee), rinsing with fresh water.
  13-59. Defective paint coatings on outside painted surfaces should be removed with paint remover. The cleaned surface must then be washed with paint thinner, scrubbed with paint cleaner and water, and rinsed with fresh water.
  13-60. Good paint on inside painted surfaces should not be removed. Flaking, scaling, or peeling patches may be removed with hand scrapers, being careful not to damage the aluminum surface. Dulling or rounding the corners of scrapers will help prevent nicking the aluminum. The edges of the good paint are faired with sandpaper. Do not sandpaper the aluminum surface. Wash the entire surface with paint thinner and again with paint cleaner and water and a fresh water rinse. Never use a chipping hammer or power tool on an aluminum surface.
PREPARATION OF GALVANIZED STEEL SURFACES
  13-61. Heavy blast-cleaning of galvanized steel shall be avoided. Chipping hammers will not be used on galvanized surfaces. Old paint shall be removed by means of a hand scraper and wire brushes. Never use sandpaper on this surface.
  13-62. After scraping and wire-brushing a galvanized surface, wipe the surface with paint thinner. As soon as the surface is dry, apply a liberal coat of primer.
SHIP BOTTOMS
  13-63. The condition of the ship's bottom has considerable effect on steaming performance. Before applying paint to the bottom, be sure that it has been cleaned carefully. A special problem is involved near the waterline where oil and grease often accumulate. Paint applied over grease will not adhere or dry, so you must remove all traces of grease with a solvent. Gasoline was formerly used for this purpose but recently kerosene solvent-emulsion cleaners have been developed. They are inexpensive and efficient and do not constitute as great a fire hazard as gasoline.
  13-64. DO NOT REMOVE PAINT THAT STICKS AND IS FREE FROM FOULING. Remove blistered, flaked, or loose paint by sandblasting, hydroblasting, or hand cleaning. DO NOT touch paint that adheres firmly and gives protection to the bottom. Clean antifouling paint, which is over 2 years old, to its original color and apply two additional coats. Where paint is completely removed and the metal is bare, replace all coats of the bottom system.
PIPING SYSTEM
  13-65. Remember that you must not mar the surface when cleaning piping systems. The ordinary procedure is to remove loose paint from the pipe with a scaling tool; then go over the pipe with a wire brush to remove all loose particles. When a big overhauling job is underway, at some shipyards the pipes may be taken out and sandblasted while other machinery is being moved.
  13-66. One way the inside of a pipe is cleaned is with a tool called a vibrator. The vibrator has a long shank with a mallet-like head. The shank is inserted in the pipe and the vibration of the head removes scale and rust. Then an air hose is used to blow all the loose flakes out of the pipe.
ELECTRICAL EQUIPMENT
  13-67. No attempt should be made to remove paint from electrical cables, fixtures, control enclosures, or switchboards. If you take the paint off a cable, you may injure the protective armor and watertight sheath directly beneath it. Damage to the sheath will allow moisture to enter and will result in grounding. Twisting or bending a cable to remove paint from it might destroy the watertightness of the packing in the bulkhead stuffing tubes.
  13-68. When scraping paint, sandblasting, or painting near electrical equipment, be sure that the equipment is covered to protect it from paint, dust, or sand particles. After your work is finished, clean the electrical equipment thoroughly, using a vacuum cleaner if you have one. Remember that paint dust is full of abrasive and semiconducting particles, which can seriously damage electrical equipment.
  CAUTION: Note the flash point listed on container labels and take adequate precautions. Apply only when electrical equipment in the same and adjacent compartments is de-energized and surfaces to be painted are in a cold-iron condition.
PAINT PREPARATION
  13-69. No matter how high the quality, paint will give poor service if not thoroughly mixed before applying. When paint stands for long periods of time, the pigment settles to the bottom of the container, and the vehicle rises to the top. Naturally, the paint must be remixed before use. The best system for mixing is to pour off most of the vehicle and mix the remainder thoroughly. Then add a small amount of the liquid at a time, until the entire vehicle has been added and the paint is uniform. To make sure the paint is thoroughly mixed, pour the paint back and forth between two cans (Figure 13-5). This process is called "boxing" and ensures a smooth and even mixture.


Figure 13-5. Steps in Boxing

  13-70. Some of the newer paints require special mixing procedures, including induction times (waiting periods) before use. For epoxy or polyurethane paints, carefully follow the manufacturer's instructions regarding mixing, induction time, and applying.
  13-71. When opening a paint can, you may find that a "skin" has formed on the surface of the paint. This must be removed carefully and thrown away. All particles of pigment, dirt, and skin should be taken out by straining the paint through a wire screen or cheesecloth. Straining should be done after the paint has been mixed thoroughly.
  Note: During storage, turn paint containers "bottoms up" periodically (at least once every 90 days) to reduce the labor involved in mixing paint.
PAINTING BY BRUSH
  13-72. Smooth and even painting depends as much on good brush work as it does on good paint. There is a brush for almost every purpose, so be sure you use the right brush and keep it in the best condition. Table 13-1 lists the name and general use of the most frequently used brushes.

Table 13-1. Types and Uses of Brushes

  13-73. The two most useful brushes are the flat brush and the oval sash and trim brush. A skillful painter using a flat brush can paint almost anything aboard ship. Flat brushes are wide and thick, carry a large quantity of paint, and provide a maximum of brushing action. Sash brushes are handy for painting small items and those hard-to-get places and for cutting in at corners. The most common used brushes aboard ship are shown in Figure 13-6.
  13-74. Many of the brushes are made of horsehair and other natural bristles. More and more brushes are being made of synthetic bristles such as nylon. These brushes are much cheaper and provide comparable brushing action.


Figure 13-6. Types of Brushes

CARE OF BRUSHES
  13-75. Brushes are only as good as the care given them. The best brush can be ruined very quickly if not properly treated. If you follow the suggestions given, your brushes will last longer and give better service.
  13-76. When bristles of paintbrushes were set in wood, painters dampened the wood to cause it to swell and hold the bristles more tightly. However, almost all modern paintbrushes have bristles set in rubber or in some composition material. This means, of course, that wetting the end of the handle holding the bristle is useless. In fact, this practice will probably cause harm because it will tend to make the metal band (ferrule) rust faster. To make a new natural bristle brush more flexible and easier to clean, rinse it in paint thinner and soak it in boiled linseed oil for about 48 hours. Drain the oil from the brush before using. Wipe the bristles clean and wash them in a solvent or other oil remover. Synthetic bristle brushes do not require special treatment before use.
CARE AFTER USE
  13-77. Every paint locker should have a container with divided compartments for stowing different types of brushes (that is, paint, varnish, shellac, and so on) for short periods of time. The container should have a tight cover and a means of hanging brushes so that the entire length of the bristles and the lower part of the ferrule are covered by the thinner or linseed oil. The bristles must not touch the bottom because they eventually will become distorted, making it impossible to turn out an acceptable job with them.
  13-78. A simple brush keeper is shown in Figure 13-7. Drill a small hole through the brush handle and support the brush so that the ends of the bristles are allowed to soak in paint thinner or linseed oil. The keeper may be square or round, but it must have a tight lid to prevent evaporation and to avoid being a fire hazard.


Figure 13-7. Small Brush Keeper

  13-79. Brushes to be used the following day should be cleaned in the proper thinner and placed in the proper compartment of the container. Brushes to be used later should be cleaned in thinner, washed with soap (or detergent) and water, rinsed thoroughly in fresh water, and hung to dry. After drying, they should be wrapped in waxed paper and stowed flat. Brushes should not be left soaking in water; the water causes the bristles to separate into bunches, flare, and become bushy. The proper cleaners for brushes used with different finishes are shown in Table 13-2.
  13-80. Remember that paint-soaked brushes should never be left in an open can of paint or exposed to the air. Good brushes are hard to get -- take care of them. Clean them immediately after use; then store them properly.

Table 13-2. Brush Cleaners for Different Finishes

HOW TO USE A BRUSH
  13-81. There is an art to using a paintbrush properly. It is an art you will have to master if you are going to become a good painter. The following general hints will help you. Read them once to see how many mistakes you have been making. Then concentrate on each point separately until you are sure you have it mastered.
  13-82. Hold the brush firmly, but lightly, in the position shown in Figure 13-8. Do not put your fingers on the bristles below the ferrule. Hold the brush in a way that will permit easy wrist and arm motion.


Figure 13-8. Correct Way to Hold a Brush

  13-83. Do not try to paint with the narrow edge when using a flat brush. That will wear the corners down and spoil the shape and efficiency of the brush. When using an oval brush, do not let it turn in your hand. An oval brush that has been revolved too much will wear to a pointed shape and become useless. Do not poke oversized brushes into corners and around moldings. Such use will ruin a good brush by bending the bristles. Use a smaller brush that will fit into such spots.
  13-84. Work the paint well into the brush before you start to paint. Hold the mixing paddle tightly over the rim of the bucket, dip the brush into the paint, and then wipe the brush clean across the edge of the paddle. Do this several times so you will be sure the brush is filled with paint.
  13-85. Dip slightly less than half of the bristles into the can when applying paint. Slap the brush lightly against the side of the can, then apply it to the surface to be painted. To avoid paint from dripping off your brush, be careful not to overfill your brush.
  13-86. Hold the brush at right angles to the surface being painted, with the ends of the brush just touching the surface. Lift the brush clear of the surface when starting the return stroke. If the brush is held obliquely and is not lifted, the painted surface will be uneven, showing laps and spots and a "daubed" appearance. A brush that is held at too great an angle will soon wear away at the ends.
PAINT APPLICATION
  13-87. Use the "lay on" then "lay off" method to completely cover with paint (Figure 13-9). "Laying on" means applying the paint first in long, horizontal strokes. "Laying off" means crossing your first strokes by working up and down.


Figure 13-9. Laying On and Laying Off

  13-88. The laying-on and laying-off method distributes the paint evenly over the complete surface with the least amount of paint. A good rule is to lay on across the shorter distance and lay off in longer direction. When painting bulkheads or any vertical surface, lay on in horizontal strokes, lay off in vertical strokes.
  13-89. Always paint the overhead first and work from the far corner. By working the overhead first, you can keep the bulkhead free of drippings by wiping up as you go along.
  13-90. When painting overhead surfaces, paint strokes on the ceiling panels should normally be laid fore-and-aft, and those on the beams, athwartships. But where panels contain many pipes running parallel with the beams, it is often difficult to lay off the ceiling panels fore-and-aft. In such cases, you will get better results by laying off the panels parallel with the beams.
  13-91. To avoid brush marks when finishing a square, stroke toward the last square finished, gradually lifting the brush near the end of the stroke while the brush is still in motion. Every time the brush touches the painted surface at the start of a stroke, it leaves a mark. For this reason, never finish a square by brushing toward the unpainted area, but always end up by brushing back toward the area already painted.
  13-92. When painting pipes, stanchions, narrow strips, beams, and angles, lay the paint on diagonally. Lay off along the long dimension (Figure 13-10).
  13-93. Always carry a rag for wiping dripped or smeared paint.


Figure 13-10. Painting Pipes and Stanchions

FILM THICKNESS
  13-94. For interior painting, paint must be applied in the lightest possible coat that will cover the surface. Several reasons for this are:
 
  • Heavy layers of paint constitute a fire hazard--the thicker the paint film, the more readily it will burn. Also, if paint is applied heavily, it is likely to entrap solvents and thinners that burn rapidly.
  • Thick coats of paint tend to crack and peel. They are likely to be uneven and may show marks and scratches more readily than thin coats. Thick coats of paint do not penetrate as well as thin ones and do not dry as hard to a surface.
  If an interior surface has already had a total of four coats of paint (including primer) or if the total thickness of the existing paint amounts to 0.005 inch, the old paint should be removed before adding any more paint.
WORKING CONDITIONS
  13-95. Painting should not be attempted at a temperature below 32 F. In cold weather, moisture condenses on surfaces and the paint will not stick. The thinner also evaporates too slowly, increasing the drying time.
  13-96. For best results, paint during warm weather (between 60 F and 80 F). In hotter weather, paint dries too rapidly and makes brushing and rolling difficult.
  13-97. Humidity and ventilation are also important considerations. High humidity may cause condensation on the bulkheads and make painting difficult. To reduce humidity inside, you can increase the temperature or improve the ventilation. Proper ventilation is also necessary to carry off the solvents and to furnish oxygen so the paint will dry properly.
STRIPING
  13-98. Striping can be a relatively easy job if you use masking tape. You can use either a brush or spray gun with masking tape. There are two basic methods to follow, depending on whether the surface to be striped has been finished.
Striping Method Number 1
  13-99. If the surface is already painted and you do not want to do a complete repainting job, you can still add stripes without marring the finish. First decide on the position and width of the stripe; then apply masking tape to both sides of the stripe. Figure 13-11 shows how to apply the tape. It is a good idea to add a further protective covering on both sides, wide enough to prevent daubs or overspray from striking the rest of the surface. Placing newspapers or wrapping paper in the proper position before painting may also provide protection. The striping color is then sprayed or brushed on. When the paint has set, the masking tape is removed.


Figure 13-11. Applying Masking Tape

Striping Method Number 2
  13-100. If the surface is unfinished, the process of striping is a little different. First decide on the position and width of the stripe; then spray or brush the color on, allowing the paint to overlap the edge of the stripe a little on both sides. Allow the striping color to dry thoroughly, then cover the exact area of the stripe with masking tape. Attach the tape firmly, but do not stretch it too much. Rub or roll it down to smooth out the wrinkles and make a tight, protective covering. Some painters recommend as the next step a light "fog" covering of the finishing material right over the tape. This will help to prevent the final coat of paint from sticking to the edges of the tape, cementing the tape to the surface. Now you are ready to spray or brush on the finishing coat. Do this right over the masking tape. When the surface coat has set, remove the tape to reveal a clean-cut stripe.
REMOVING MASKING TAPE
  13-101. There is a trick to removing masking tape so it will not mar the surface. The right way is to pull the tape off somewhat diagonally and back upon itself. The wrong way is to pull the tape directly away from the surface at a right angle. Figure 13-12 shows the proper angle. Work slowly, with your hands moving close and parallel to the surface.


Figure 13-12. Removing Masking Tape

  13-102. There may be a slight ridge along the edges of the stripe after you pull off the masking tape. If this is too noticeable, you can scrape it off after it has dried thoroughly and then rub it smooth with a rubbing compound.
STENCILS
  13-103. All ships or boat companies should have adjustable stencil sets with locking edges. These sets are made of brass and include punctuation marks as well as the 26 letters of the alphabet and numerals from 0 through 9. The sets come in three sizes: 1/2 inch, 1 inch, and 2 inches. The edges of each piece are crimped allowing the use of a combination of letters, figures, and punctuation marks by slipping the edge of one piece into the edge of the adjoining piece.
  13-104. Flat-ended brushes especially designed for stenciling are available, but an old toothbrush makes an acceptable substitute. Use the stencil paints available in general stores. After stenciling one surface, wipe off the back of the stencil before laying it on the next surface to be stenciled. Make sure the stencil does not slip while applying the paint. Stencils should be cleaned immediately after use--the brass ones with the proper thinner, the other type with only a clean soft rag.
CUTTING IN
  13-105. A painter who has learned to "cut in" properly can do a job in less time than it takes another person to apply masking tape. Cutting in is not hard and anyone with a fairly steady hand can learn it in a short time. Suppose you have to cut in the angle between an overhead and a bulkhead. Start at one corner. Hold your brush at an angle of about 75 to 80 degrees from the bulkhead and about 10 degrees from the overhead. Run your brush along in fairly swift, long, smooth strokes. This is one job where working slowly will not produce better results. The slower your stroke, the wavier the line.
  13-106. If there is no definite break, such as the angle between bulkheads and overheads or decks, you should draw a line to follow. You can do this either with a straightedge or by snapping a chalk line. To snap a chalk line, first mark a couple of reference points, one at each end where the line will be. Then chalk the line and stretch it taut between the reference points. Have somebody pull the center of the line about 6 inches out from the surface and let it snap back against the surface. This leaves a neat, straight line. Cut in as already described. You may want to paint up close to the line and then cut in, but usually it is best to cut in first and paint out from that line.
PAINT ROLLERS
  13-107. The dip type of paint roller consists of a replaceable, knotted Dynel, plush fabric roller having a solvent-resistant paper core which rotates on the shaft of a corrosion-resistant steel frame.
  13-108. Large areas, such as decks and ship's sides, free of rivets, bolts, cable, pipes, and so on, can be quickly covered with paint by using rollers. In order to get uniform coverage, always try to pick up the same amount of paint with your roller, and paint the same size area. A 7-inch roller filled with paint will cover about a square yard; a 9-inch roller, of course, will cover slightly more. Dip your roller in the paint at the lower end of the tray and roll it lightly toward the raised end. Repeat this process as necessary to fill the roller evenly. Then quickly apply it to the surface to be painted, using the same lay-on, lay-off technique used when brush painting. A moderate amount of pressure must be applied to the roller to ensure that the paint is worked into the surface. If pressure is not applied, the paint will not adhere and will peel off.
  13-109. The fabric cylinder should be stripped from the core after use, cleaned in the solvent recommended for the paint used, washed in soap and water, rinsed thoroughly, and replaced on the core to dry. Combing the pile of the fabric while damp will prevent matting.

SPRAY GUNS AND THEIR USE

  13-110. A spray gun is a precision tool in which paint is sprayed out through a nozzle by air pressure. The mixing area may be outside or inside the gun's spray cap.
CLASSES OF SPRAY GUNS
  13-111. Spray guns are classed according to where the air and paint are mixed (external-mix, internal-mix), how the air is controlled (bleeder, nonbleeder), and how the paint is fed to the nozzle (suction-feed, pressure-feed).
External-Mix Spray Gun
  13-112. In an external-mix gun, the air and paint are mixed outside and in front of the air cap as shown in Figure 13-13. This type of gun requires high air pressure, thereby using more cubic feet of air per minute than does an internal-mix gun. Atomization of the paint is extremely fine, however, and the size of the spray pattern can be controlled. There is no wear on the air nozzle. With different nozzles, an external-mix gun works with both suction and pressure feeds.
Internal-Mix Spray Gun
  13-113. In an internal-mix gun, air and paint are mixed within the gun as shown in Figure 13-14. In this type of gun, atomization of the paint is coarse, and the spray pattern is fixed. This gun works only with a pressure-feed, but the pressure is lower and the amount of air used is less than for the external-mix gun. Because atomization of the paint is coarse, more paint is applied on each pass.


Figure 13-13. External-Mix Air Cap

Figure 13-14. Internal-Mix Air Cap

Bleeder and Nonbleeder Spray Gun
  13-114. The bleeder type of gun is one in which air is allowed to leak or bleed from some part of the gun to prevent air pressure from building up in the air hose. In this type of gun the trigger controls only the fluid. It is generally used with small, air-compressing outfits that have no pressure control on the air line.
  13-115. The nonbleeder gun is equipped with an air valve that shuts off the air when the trigger is released. It is used with compressing outfits having a pressure-controlling device.
Suction Feed Spray Gun
  13-116. In a suction-feed gun, the air cap is designed to draw the fluid from the container by suction (Figure 13-15) in somewhat the same way that an insect spray gun operates. The suction-feed spray gun is usually used with 1-quart (or smaller) containers.
Pressure-Feed Gun
  13-117. A pressure-feed gun operates by air pressure (Figure 13-16) which forces the fluid from the container into the gun. This is the type used for large-scale painting.


Figure 13-15. Suction-Feed Air Cap

Figure 13-16. Pressure-Feed Air Cap

PARTS OF THE SPRAY GUN
  13-118. The two main assemblies of the spray gun are the gun body assembly and the spray head assembly. Each of these assemblies is a collection of small parts, all of which are designed to do specific jobs.
  13-119. Figure 13-17 shows the principal parts of the gun body assembly. The air valve controls the supply of air and is operated by the trigger. The spreader adjustment valve regulates the amount of air that is supplied to the spreader horn holes of the air cap. This will vary the paint pattern. It is fitted with a dial, which can be set to give the desired pattern. The fluid needle adjustment controls the amount of spray material that passes through the gun. The spray head locking bolt locks the gun body and the removable spray head together.


Figure 13-17. Cross-Section of a Spray Gun

  13-120. Most guns are now fitted with a removable spray head assembly. This type has many advantages. The head can be cleaned more easily; the head can be quickly changed to use a new color or material; and, if damaged, the head alone can be replaced, using the old gun body.
  13-121. The principal parts of the spray head assembly are the air cap, the fluid tip, fluid needle, and spray head barrel (Figure 13-18).
  13-122. The fluid tip regulates the flow of the spray material into the air stream. The tip encloses the end of the fluid needle. The spray head barrel is the housing, which encloses the head mechanism.


Figure 13-18. Principal Parts of the Spray Head

Containers
  13-123. The cups or tanks, which hold the spray material before delivery to the gun, are called containers. The job to be done determines which one of several kinds of containers to use.
 
  • Suction-feed cups are used for small quantities of lightweight and medium weight spray materials, such as lacquers.
  • Gravity-feed cups are also small and are attached directly to the top or side of a gun. They normally are used only on artist's and decorator's guns or on small touch-up guns.
  • Pressure-feed cups (Figure 13-19) are considered best for handling small quantities of enamels, plastics, or other heavy materials on jobs that need fine adjustments and speed of application.
  • Pressure tanks are large containers with a capacity of 2 to 60 gallons. Figure 13-20 shows a common type of pressure tank. There are two general types, the regulator type and the type that uses the equalized pressure tank.
  13-124. The equalized pressure tank is equipped only with a safety valve and a release valve. The regulator type is equipped with one or two regulators, a safety valve, release valve, and pressure gauge. It may also have one or two hand-operated or motor-operated agitators. If there is only one regulator, it regulates the fluid pressure in the tank only. If there are two regulators, one regulates the fluid pressure in the tank while the other regulates the air pressure from the container to the gun. Each regulator operates independently of the other.


Figure 13-19. Pressure-Feed Cup

Figure 13-20. Pressure Tank

  13-125. The pressure tank shown in Figure 13-20 is equipped with air outlets and fluid outlets. The fittings, pressure regulators, and gauges permit the use of more than one spray gun at the same time.
  13-126. Sometimes, instead of pouring the material directly into the tank, you can put a separate container (called an insert container) into the tank. With this type of container it is possible to make quick changes of color or material without having to clean the tank. You can also mix your materials ahead of time and have them on hand.
Hose Lines
  13-127. Spray gun hoses are of two varieties--one kind to handle air and another to handle liquids. Air hoses are usually made of braid-covered tubing, with either one-braid or two-braid construction. Fluid hoses are made of a special, solvent-resisting material.
AIR SUPPLY
  13-128. Spray guns are operated by compressed air, which may be supplied by either portable or installed compressors. However, aboard ship, guns using pressure tanks are usually connected to the low-pressure ship's service air line. Pressure on this line is usually from 100 to 125 psi, but this is cut down to spraying pressure at the tank by a pressure regulator valve.
  13-129. The manufacturer's instructions for the operation of air compressors must be followed exactly. If you intend to use air from the low-pressure line for long periods, it is a good idea to inform the engineering officer of the watch.
  13-130. To properly spray paint, the air should be dry and free from dust. All air, in varying amounts, contains moisture and dust and some means must be provided to remove both. An air transformer (Figure 13-21) is usually used to remove moisture and dust. The air transformer is also called an air separator or air regulator.
  13-131. Air enters through an air inlet, passes through a series of baffles and a filter chamber, and then through a regulator diaphragm which adjusts the pressure. Normally, the transformer should be drained daily. If the weather is damp, it should be drained several times daily. You do this by turning a drain cock at the bottom. The packing and filtering material should also be changed at regular intervals.


Figure 13-21. Air Transformer

OPERATION OF THE SPRAY GUN
  13-132. Squeezing the trigger of the spray gun opens the air valve, admitting compressed air through the air inlet. The air passes through the gun body to the spray head. In the most common (external-mix) type of spray head, the air does not come in contact with the paint inside the gun, but is blown out through small holes drilled in the air cap. Paint is shot out of the nozzle in a thin jet, and the force of the air striking it breaks the jet into a fine spray. You can control this spray, making it into various patterns, by setting the air-control screw that regulates the spreader-adjustment valve. Turn the screw clockwise for a round spray. For a fan spray turn it counterclockwise. Turn the fluid-control screw clockwise to increase the flow. To obtain the same coverage over the wider area, the flow of paint must be increased as the width of the spray is increased. The handling of a spray gun is best learned by practice, but here are some tips.
  13-133. Before starting to spray, check adjustments and operation of the gun by testing the spray on a surface similar to that which you intend to coat.
  13-134. There are no set rules for spray gun pressure or for distance to hold the gun from the surface because pressure and distance vary considerably with the nozzle, the paint used, and the surface to be coated. The minimum pressure necessary to do the work is the most desirable, and the distance is normally from 6 to 10 inches.
  13-135. Always keep the gun perpendicular to and at the same distance from the surface being painted (Figure 13-22). Start the stroke before squeezing the trigger, and release the trigger before completing the stroke (Figure 13-23). If the gun is not held perpendicular or is held too far away, part of the paint spray will evaporate and strike the surface in a nearly dry state. This is called "dusting." Failing to start the stroke before starting the spray or spraying to the end of the stroke will cause the paint to build up at the end of the stroke, and the paint will run or sag. Arching the stroke makes it impossible to deposit the paint in a uniform coat.


Figure 13-22. Hold Spray Gun
Perpendicular to Surface

Figure 13-23. Proper Spray Gun Stroke

  13-136. When spraying the inside and outside corners, stop 1 or 2 inches short of the corner. Do this on both sides, then turn your gun on its side and, starting at the top, spray downward, coating both sides at once (Figure 13-24).
  13-137. If you are spraying a large area from which small parts and pieces protrude, first lightly coat those items. Then go over the whole surface.
  13-138. For example, if you are painting a compartment, first spray the hatch coamings, door frames, rivets, exposed bolt heads, and all small items secured to the bulkheads. Then do the entire compartment. This eliminates a lot of touching up later.


Figure 13-24. Correct and Incorrect Methods of Spraying Corners

COMMON SPRAYING DEFECTS
  13-139. The most common defects in sprayed-painted coats are "orange peel," runs and sags, pinholes, blushing, peeling, and bleeding.
Orange Peel
  13-140. This is a general term used to describe a painted surface that has dried with a pebble texture resembling an orange peel. This may be caused by using improper thinners, a spray which is not fine enough, holding the gun either too far or too close to the surface, improper mixing of the material, drafts, or low humidity.
Runs and Saps
  13-141. These are usually the result of using material that is too thin. Sags result from too much material. Runs and sags can also be caused by allowing too big a lap in spraying strokes and by poor adjustment of the spray gun or pressure tank. Dirty or partially clogged passages for air or fluid will also cause uneven distribution.
Pinholes
  13-142. These may be caused by the presence of water or excessive thinner in the paint or by too heavy of an application of quick drying paint. Either way, small bubbles form and break in drying, leaving small holes.
Blushing
  13-143. This resembles a powdering of the paint. The cellulose material in the paint separates from its solvent and returns to its original powder form. Water is usually the cause of this, either moisture on the sprayed surface or excessive moisture in the air. When blushing occurs, you will have to remove the defective coating because the moisture is trapped within the material and will remain there unless the coating is removed.
Peeling
  13-144. This is almost invariably due to carelessness in cleaning the surface. Before any spraying is attempted, the surface must be absolutely clean. Cheap spray materials sometimes will give poor adhesion, but you will not have this trouble if you always use standard paints.
Bleeding
  13-145. This occurs when the color of a previous coat discolors the finish coat. Paint containing a strong aniline dye (synthetic organic dye) will do this when another color is sprayed over it.
CARE OF THE SPRAY GUN
  13-146. Spray guns (as well as paint containers and hoses) must be cleaned thoroughly after they are used.
  13-147. Figure 13-25 shows the steps in cleaning a pressure-feed gun. First, back up the fluid, needle-adjusting screw and release the pressure from the pressure tank by means of the release valve. Hold a cloth over the air cap and pull the trigger (this forces the spray material back into the tank). Now remove the fluid hose from the gun and run a solvent through the hose. There is a special hose cleaner made for this purpose. Dry out the tip and clean the tank. Soak the air cap in solvent. If the holes are clogged, use a toothpick to clean them. Put all clean parts back in place, and the gun is ready for use again.


Figure 13-25. Steps in Cleaning a Pressure-Feed Gun

  13-148. Figure 13-26 shows how to clean a container-type gun. First remove the container. Then hold a cloth over the air cap and pull the trigger. Empty the container and pour in a small quantity of solvent. Attach the container to the gun and spray in the usual way. This process cleans out all passageways. Clean the air cap by soaking it in a solvent and then replace it. Some spray gun troubles, their possible causes, and their remedies are listed in Table 13-3.


Figure 13-26. Steps in Cleaning a Container-Type Gun

Table 13-3. Spray Gun Troubleshooting Chart

Lubrication of the Spray Gun
  13-149. Your spray gun also needs a little lubrication. The fluid needle packing should be removed occasionally and softened with oil. The fluid needle spring should be coated with grease or petrolatum. Figure 13-27 shows the parts and the oil holes in which you occasionally should put a few drops of light oil.


Figure 13-27. Lubrication Points of a Spray Gun

How to Remove the Spray Head
  13-150. To clean, to repair, or to change paint color, you may have to change the spray head. First, remove the gun -from the air and fluid hose lines. Holding the gun in the left hand, pull the trigger all the way back and loosen the locking bolt with the wrench provided for the purpose. Push the trigger forward as far as possible and pull the spray head forward (Figure 13-28). To replace the head, push the trigger forward and insert the spray head. Then hold the trigger back and tighten the locking bolt.
What Not to Use in Your Spray Gun
  13-151. As a general rule, paints, enamels, lacquers, synthetics, varnishes, and shellacs are suitable for spray work with ordinary equipment. Except in an emergency, material containing small gritty particles (such as alkaline coverings, rubber hose paints, plastics, and mastic paints) should never be used in standard equipment. They will damage the ordinary machines; therefore, use only the special outfits designated for use with those paints.
RESPIRATIORS