DIVISION. Automotive refinishing techniques

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1 DIVISION Automotive refinishing techniques High quality finishes on automobiles can be achieved when good materials, proper equipment, and correct techniques are used. Spray painting equipment for the auto refinishers consists of spray guns and cups (either siphon or pressure feed) an air compressor of adequate size; oil and water extractor and air regulator combination to filter air and regulate pressure; air hose of sufficient (inside diameter) size to convey air from the extractor to the spray gun without causing an excessive drop in pressure; and a spray booth or enclosure to insure a healthy, safe, dust free working area. A separate drying area and force-drying equipment should also be included where the volume of business warrants this additional production facility. SPRAY GUN A production type spray gun should be used to insure perfect atomization and application of the paint in a minimum amount of time. For siphon feed work, a suitable air nozzle and fluid nozzle will be required. A one-quart capacity siphon cup is usually used. The cup is attached directly to the spray gun. The fluid nozzle normally used for siphon feed will have a.070" dia. orifice. For faster application an.086" dia. orifice may be used. The.070" dia. orifice fluid nozzle requires an air nozzle capacity of about 11.5 CFM (cubic feet per minute) of air at a spraying pressure of 50 PSI (lbs. per sq. in.). For the.086" dia. orifice fluid nozzle, an air nozzle passing about 13 CFM at 50 PSI will be required. For pressure feed application, a fluid nozzle in the range from -046" to.05y dia. orifice should be used to eliminate sags. A pressure feed air nozzle passing about 14 CFM will be required. PAINT CONTAINER A one quart siphon type cup is connected directly to the fluid inlet on the spray gun. For pressure feed, a separate two-quart pressure feed cup is connected to the spray gun with a short length of solvent resistant, lined fluid hose. Where a large volume of paint is applied, a two-gallon or larger size pressure paint tank may be used to supply paint to the spray gun through a solvent resistant, lined fluid hose. Pressure tanks should be equipped with agitators to prevent pigment settling and color changes. Model Outfit Consists of 2001 Gun 638 x 63 PB, gal, non ASME Tank with air motor agitator, air valve, twenty-five ft. air hose ass'y., twentyfive ft. air hose ass'y. and twenty-five ft. fluid OIL AND WATER EXTRACTOR AND REGULATOR An adequate oil and water extractor should be used to remove contamination from the shop air line and provide a controlled air pressure supply to the spray gun. A minimum extractor capacity of 30 CFM should be provided. All parts should be corrosionresistant. Sensitive type regulators should be included to hold adjusted air pressure accurately. Model Outfit Consists of 2001 Gun with 638 x 63PB Nozzle, two-qt. pressure cup with regulator, air adjusting valve, five-ft. air hose ass'y. and five-ft. fluid hose ass'y DripProof Cup Nozzle Set-Up 36 x 36 SD

2 AIR COMPRESSOR The air compressor must furnish the CFM of compressed air necessary to meet the continuous requirements of the.spray gun. The CFM actual delivery of the compress0r.k the determining factor-disregarding the horsepower of the motor, piston size, length of stroke, or CFM displacement. A one horsepower air compressor will produce about 4 CFM at 100 PSI. A five horsepower air compressor will produce about 20 CFM at 100 PSI. This is air actually delivered. For a siphon type spray gun, the compressor should be capable of delivering 11.5 or more CFM. For a pressure type spray gun, its delivery should be at least 14 CFM. OPERATING SPRAY EQUIPMENT A siphon feed spray gun uses a large fluid tip and a siphon type air nozzle. The pressure feed spray guns use a small fluid tip with small diameter orifice and pressure type air nozzle. Fluid nozzle protrudes.015 to.020 Siphon Air Nozzle External Mix Type Siphon or Pressure Feed Fluid nozzle flush Pressure Air Nozzle External Mix Type Pressure Feed Only Primary atomizing ports Secondary Atomizing Ports HOSE Adequate air volume and pressure at the spray gun is necessary to insure complete atomization of the paint being sprayed. Undersize air hose will create a serious pressure drop which may result in underatomization of -@LAir hose between the air regulator and spray gun should be minimum of 5/16 inside diameter. PRESSURE DROP Pressure Reading (psi) at the Extractorm*u'ator Pressure (psi) at the Gun for Various Hose Lengths 5ft. loft. 15ft. 20ft. 25ft. 50ft Hose''D' '4-inch Hose''D' '16-inch NOTE: Quick-change hose connectors will further reduce the pressure that reaches the gun. Pressures given are approximate and apply only to new hoses. 2 A production type spray gun has two manual adjustments that must be properly set in order to achieve a good operating result. The two adjustments are the side port (air) control and the fluid control. P FLUID CONTROL

3 .,...a.e. '* \ I..\ 1 The side port control, when fully closed, shuts off the air to the horns on the air nozzle and a round spray pattern results. As this control is gradually opened, air is emitted from the horns on the air nozzle and the spray pattern is changed from round to elliptical. This control allows the operator to select a width of spray pattern to suit the object being sprayed. For touch-up work or spotting in, a round pattern or small fan is used. For large panels or overall spraying, the gun is adjusted to a wide pattern. This pattern should not be so wide that the operator cannot see both top and bottom edges to make sure that they are both wet edges. The fluid control adjusts the amount of paint coming out of the gun. When fully closed, no paint will flow; when fully opened, paint flow will be maximum. This adjustment allows the operator to select a setting that will give the proper paint flow for the job. On spot work, a minimum flow is used. On large panels or overall painting, maximum flow is usually used. The air pressure used at the gun must be adjusted to atomize the paint being sprayed. The pressure used will vary with the viscosity of the paint and, to some extent, the type of paint, e.g., lacquer, enamel, acrylic. Gun air pressure is adjusted and controlled by the air regulator which is a functional part of some oil and water extractors. The proper pressure can only be arrived at by a series of test spray patterns. Too low an air pressure will result in a heavycentered spray pattern and underatomized paint which will be rough or show a heavy "orange peel". Atomizing pressure that is too high will result in a split spray pattern, or a dry spray pattern, and may also cause "orange peel", due to lack of proper flowout of material. As a matter of general practice, the atomizing pressure at the spray gun will range from 30 to 60 PSI. When the pattern is right, the pressure is right. When a pressure feed spray gun is used it will require less atomizing air pressure than one using a siphon type nozzle. Pressure type nozzles use more air flow (CFM) and are more efficient in atomizing paint..:.:..:*-..: '..:*y 3, '3'. -...*..,% :....*,. :..a,.*..?..:4,14., fk;.;.:.;.*. ' :;. f,.tt%';r! -,:.;:,.;,\-.*,-;..:;*:-...,-.. #:"::;:'...;.:,.:..,.,. d:,, *.A) -'.*-..:.-,~;%;:..: :.-:.:e-!<.. *.I ic......: 1:; :., e:>:::$..:./ 'i.,:.?.+ t<g~?. - I *..x.-..,. :\;.;...: ;:+:.. j..:... t{t)j!.-?.!:;p..a..:. *., ;,.-.%.-.!*:. :. '..,.):;: :..e.. y :,*..,: *.:*.c-...:;...:.. : ;...* *!Y..*.i...* *. *, *.';, i.:::,. i :',.'..!; a: : * ; ;.,:* :.' T...;,...?..'. 6..I.. \,* ;. :..,':.(:.:.?; : i ;*-'-, -.,.,*...,....:, ;;:;;;i.\...:.:,.: < b.:; e ; - <..!,.-;-.e.....' a;.-..,...,.: * ;:v *.*,..'.:.-;...,. t.-:.4. i' :., :. \.:.. ':& *day-.:,l;.. :;..:, :...;,;.:. 1...,....' f 1.. *,*.; -*' 7 :;..',.--.-'*:.\'i.i;>;-... s 1::.'.'.a a,;,, ;*-!*.. ; ; *+,*:.i.;..,..;,e&.! -a':;:,i...-.y,.... *.*.. f 1': I *....., -.. '.. :: c ' When setting up spray equipment, follow paint manufacturers' recommendations on the preparation of materials to be used. Be sure all paint is carefully strained through a fine-mesh strainer before pouring it into the paint container or cup. Once this has been accomplished, the first step in spray gun operation is to adjust the gun and air pressure until the desired pattern and atomization are achieved, using the lowest possible pressures. Test the spray pattern on paper or test panels. A uniform, symmetrical pattern is necessary. Maintain a hand-span (6" to 8") between the gun and the surface being painted to avoid sags or a dry spray condition. Always direct the spray so it is perpendicular (90 degrees) to the plane of the surface being painted. 3

4 To correct pattern distortions, clean the air nozzle and fluid tip thoroughly, inside and out, with a solvent and a soft bristle brush. Work from a wet coat. Use slow, steady strokes across the surface from one side to the other. Never use a fanning or arcing motion. To insure better, smoother coverage, each stroke should overlap the previous one by 50%. Cross-hatching is similar to lapping except that lapping is done in both directions, vertically as well as horizontally. If proper lapping is practiced in either vertical or horizontal spraying, crosshatching is not necessary unless extremely close tolerances of film thickness must be maintained. Release the gun trigger to avoid spraying beyond the section being painted. When spraying large areas, trigger the gun on and off, at the beginning and end of each stroke. Work each section being sprayed by blending into the wet edge of the previous section sprayed. Proper triggering technique at the area where the sections are joined will avoid the danger of a double coat at this point and the possibility of getting a sag. PULL TRIGGER RELEASE TRIGGER HERE After sanding, and just before color coats are applied, be sure to wipe off the area to be sprayed with a tack rag to pick up any surface dust. In applying a primer to a spot repair job, trigger the gun to avoid spraying beyond the feathered edge, except on the last coat-and then not more than 2 to 3 inches. Proper triggering minimizes sagging. Let each coat flash dry until flat, then apply the next coat. Do not fan with air to speed drying because you may contaminate the finish with the dirt and moisture in the air. Apply multiple coats until film build is slightly higher than original finish, then sand level. The time required to spot the primer will vary with the size of the area to be spotted. A small area will take 5 to 10 minutes to spot prime. A panel such as a door or fender may require 30 minutes. With practice, applying color coats on spot repairs will require about the same time as priming. CHECK-LIST OF VARIABLES CONTROLLING QUALITY IN SPRAY FINISHING A. Atomization 1. Fluid viscosity. 2. Air pressure. 3. Fan pattern width. 4. Fluid velocity or fluid pressure. 5. Fluid flow rate. 6. Distance of spray gun from work. B. Evaporation Stages 1. Between spray gun and part. 2. From sprayed part. C. Evaporation Variables Between Spray Gun and Sprayed Part 1. Type of reducing thinner. 2. Atomization pressure. 3. Amount of thinner. 4. Temperature in spray area. 5. Degree of atomization. D. Evaporation Variables 1. Physical properties of solvents, i.e., fast or slow evaporation. 2. Temperature. a. Fluid b. Work c. Air 3. Exposed area of the surface sprayed. E. Evaporation Variables From The Sprayed Part 1. Surface temperature. 2. Ambient air temperature. 3. Ambient air velocity. 4. Flash time between coats. 5. Flash time after final coats. 6. Physical properties of the solvents, Le., fast or slow evaporation. F. Operator Variables 1. Distance of spray gun from the work surface. 2. Stroking speed over the work surface. 3. Pattern overlap. 4. Spray gun attitude. a. Heeling b. Toeing c. Fanning 5. Triggering. WORKING AREA The most important factor in setting up a spraying operation is the area in which the vehicle is to be painted. Dust and dirt settling on a newly painted car will result in a very low quality finish. The area selected must be clean and free from dust and dirt particles. This can only be achieved with a complete enclosure or spray booth. The booth should conform to the standards of the National Board of Fire Underwriters as recommended by the National Fire Protection Association. 4

5 ,--\ The booth should be constructed of sheet metal so it will be fireproof and easy to clean. It should be large enough to provide adequate room for both the vehicle and spray equipment. It should also be large enough for the painter to move freely and not be crowded. A minimum size is 9 feet high, 14 feet wide, and 23 feet long. Adequate lighting should be provided to eliminate all shadows. PAINT DRYING AREA To prevent contamination of the freshly painted vehicle, the spray booth may be used as the drying area. Where production requirements of the shop require continuous usage of the booth for spray painting, a separate drying area should be provided that is accessible and connected directly to the spray booth. I An exhaust fan is required that is capable of maintaining an air movement of 100 or more lineal feet per minute throughout the booth area with a car in the painting position. Also required are filtered air intakes sized to accommodate the airflow. The booth should be so designed that all joints are sealed to prevent air leakage. Personnel Door/Observation Window \ This arrangement will allow continuous flow of work from the spray booth to the drying area without exposing the wet paint to the outside air. A booth will save time and improve quality in overall spraying of color coats. Intake Filters / \ Booth Construction ' Lighting TYPICAL CROSS-DRAFT SPRAY BOOTH 5

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7 SPRAY BOOTHS For many spray operations, booth use will be dictated by state and local codes for protection of the environment. There are, however, direct advantages to the booth user, such as: a. Safety-through removal of volatile solvent fumes. b. Improved finish quality-when overspray and rebound are removed preventing the contamination of other work in the spraying area. c. Improved working environment-for the spray operator and others in the immediate area. d. Improved community relations-through proper filtration of exhausted air, minimizing air pollution. e. Lower insurance rates-some states even provide a tax advantage to firms using spray booths. This is generally based on the reduction of air and noise pollution. In a closed system such as an automobile booth, the air make-up system should be designed to provide a slightly greater volume of incoming air than is being exhausted. This will provide a positive pressure in the spray area thus helping to keep dust and dirt from entering. NOTE: If the volume of incoming air is too great, it could cause the paint to miss the surface and pass into the room, or cause back loading of filters. 3. A purge cycle should be incorporated into a closed spray area if possible. This cycle will insure that the air is clean before any spraying operation begins. 1-1 "DOWNUNDER" SPRAY BOOTH (Cross Section) -\, U AIR MAKE-UP OR REPLACEMENT An air make-up or replacement system is important because of the large volume of air exhausted from spray booths. This exhaust is sufficient to produce two or more complete changes of air every hour. In winter, the spray area may become cold and uncomfortable, and finish problems may arise when cold materials are sprayed on cold products in cold air. An air make-up system provides correct temperatures, clean filtered air, and assures proper booth performance. 1. The air which is replaced, is heated and filtered before it enters the spray booth area. 2. These systems should be designed to replace the air being exhausted and should heat this air to a designated temperature and humidity. 6 TOP OF BOOTH

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9 t. RESPIRATORS Respirators should be worn by anyone who uses spray equipment. Respirators are designed to be. used when the atmosphere is NOT highly contaminated. Disposable filter type respirators are designed to remove only solid particles from the air, not solvent vapors. If the air is contaminated with solvent vapors, hood-type or chemical respirators should be selected. Other items such as protective clothing, barrier creams, safety glasses, and gloves may also be necessary. SPRAY OPERATION PROCEDURE Be sure the booth is thoroughly clean, and the floor is wetted down before starting the paint job. All booth doors must be kept closed during spray painting. If it is necessary to open a door, the exhaust fan should be first turned off. The operator should wear starched or lint-free clothing and spectators should not be allowed into the booth during the painting operation. Steam clean the underbody of the vehicle thoroughly and use a dusting gun to blow dirt from beneath moldings and out of seams. This should be done outside the booth area. As a final precaution, keep all equipment used in the booth clean and free of dust and dirt. This is particularly true for hoses because accumulations of dirt and dust on the outer surface of the hose may drop off on the freshly painted surface of the vehicle. Air-blow the dust from the entire vehicle before moving it into the spray booth. After the vehicle is in the booth, close the booth doors tightly and tack rag the entire vehicle again before proceeding with the spray painting operation. Reduce gun air pressure to about 20 PSI and adjust the spray gun to obtain a round spray pattern. Spray all door jambs first. To eliminate sticking of doors, close door to safety latch position only. Now adjust side port control to full pattern and increase the pressure to about 40 PSI for lacquers and acrylics, and about 50 PSI for enamels. Next, spray the inside edges of the trunk lid, the areas behind the bumpers and the inside edges of the hood. You are now ready to spray the rest of the vehicle. Several methods may be used, but the following system seems to be the most popular: starting at the right front corner post on the windshield, spray from right to left around the entire car and back to the starting point. Make sure that the air movement in the booth carries the overspray to the unpainted areas of the vehicle. Each half of the top is included with that side of the body, and the hood is usually done last as a complete area by itself. If an older model siphon cup is used, it is best to fill it only half full when spraying horizontal surfaces as this will prevent paint from spilling through the vent hole in the cover onto the surface and, further, plugging the vent hole. Using the newer DripProof siphon cup or a Steadi-grip pressure feed cup eliminates this danger and provides a longer duration be- tween container refills. Once the job is started, it should not be interrupted. At no time should it be necessary to spray or lap into a semi-dried area. If this precaution is not followed, air streaks or mottling in the paint will show up on the finish. To remove overspray or dry spray resulting from lapping of lacquer, spray a mist coat with lacquer thinner. Use care to avoid excessive wetting which will cause runs. The mist coat is applied to flow the overspray back into a smooth finish. It also helps to level any orange peel that may be on the surface. Less rubbing out and polishing will be required if this procedure is followed. The car should remain in the booth with the booth s exhaust fan operating until the painted surface is tack free. Thirty to forty-five minutes will usually be required to spray the entire vehicle if siphon feed is used. If pressure feed is used, about 20 to 30 minutes spray is required. Again, a dust free spray area will assure a smooth eye-appealing finish. CLEAN UP As soon as the painting and necessary touch-up is completed, the spray gun and cup should be thoroughly cleaned with the appropriate solvent. This will help prevent contamination during the next spray application. CLEANING AND MAINTENANCE OF SIPHON AND PRESSURE FEED EQUIPMENT Loosen the air nozzle on the siphon type gun about 2 or 3 turns. Pull the trigger and force the remaining material back into the cup. Once all the paint is out of the gun, remove cup, empty the contents of the cup, and half fill it with a clean, compatible solvent. Attach cup to gun, retighten the air nozzle and spray 7

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11 .. the solvent from the gun. This action will clean the guns fluid passages. Repeat this process until clean solvent is spraying from the gun. On pressure feed guns, release the pressure in the cup, loosen the air nozzle and force the material into the cup by triggering the gun. Take the air nozzle off. Empty the contents into a suitable container and refill the cup with a clean, compatible solvent. The air nozzle may be left off. Spray solvent from the gun and repeat this process until clean solvent is flowing from the gun. When these procedures are finished, remove the air nozzle from the siphon type gun (or the pressure type gun) and soak the gun in a clean solvent. Use a soft bristled brush to clean air and fluid nozzles. Do not use any metal objects to probe through clogged holes. Use only a brush or toothpick, if necessary. GENERAL MAINTENANCE Drain the air compressor and shop air lines daily to avoid build-up of moisture. Drain the oil and water extractor daily. Air intake filters should be changed at regular intervals. The filter change interval will depend largely upon local humidity and temperature conditions. Service... Where you want it, when you need it. Branch Offices With Warehouse facilities Atlanta. GA 5575 Spalding Drive, Norcross, GA FAX n0136e-wii... Chicago, IL 9201 Belmont Avenue, Franklin Park, IL FAX &47/ Dallas, TX Proton Road, Fanners Branch, TX FAX 21W Detroit, MI Meniman Road, Livonia, MI FAX Lo8 Angeles, CA 1405 Pioneer Street, B FAX 31W W / Milwaukee, WI Robin Lane, Brookfield, WI FAX New York, NY 1 Chapin Road, Pine Brook, NJ FAX ~~0 Pittsburgh, PA Pittsburgh Spray Equipment Company 3601 Library Road, Pittsburgh, PA Sen Francisco, CA 1459 San Mateo Avenue South San Francisco, CA FAX / Seattle, WA 1749 First Avenue, South, Seattle, WA FAX Branch Offices Cleveland. OH Indianapolis, IN 6909 Engle Road, Bldg. C, Units 31 & Polk Street, Suite 15, Greenwood, IN Cleveland, OH FAX 317/ / FAX 216l / St. Louis, MO 1725 Larkin Williams Road, Fenton, MO FAX / Sales Offices..., , , , ,4950&6747.., Houston, TX, 3910 FM 1960 West, Suite 230, , Jacksonville. FL, 5007 Buttonwood Drive Ponte Vedra Beach, FL, , Kansas City, MO, 9701 Hardy, Overland P Undale, TX, 307 Texas Drive, / Metairie, LA, 4621 Reich Street, / ~~~ ~~ Domestic Subsidiaries Binks Research and Development Corporation 1791 Range Street, Boulder, GO FAX 303/ Sames Electrostatic, Merriman Road, Livonia, MI FAX 313/ Divisions PolyCraff Systems 195 Palmer Avenue, Cottage Grove, OR FAX 5O3/ InfraTherm Infrared Curing 9201 Belmont Avenue, Franklin Park, IL FAX &47/ / nd Avenue, South, , Norfolk, VA, 2517 Dalebrook Court, Virginia Beach, VA , N. Miami Beach, FL, P.O. Box , / St. Paul, MN, 1821 University Avenue, Suite N181, , Salt Lakecity, VT, 3783 South Fifth Street West No. 3, / San Antonio, TX Lorna Doone Street, / Syracuse, NY, 136 Holiday Lane, Canandaigua, NY, , Tampa, FL, 3051 Evewood Court, Holiday, FL, / Toledo, OH, P.O. Box 5894, , Vancouver, WA, Northeast 74th Street, 98 Vemon, CT. 230 Hartford Turnpike, Winston-Salem, NC, 4212 Rayfield Drive, Canadian Sales Off ices Toronto, Ontario 14 Vansco Road, M8Z 5J5 (Headquarters) FAX 416/ / Montreal, Quebec 6412 Trans-Canada Highway, H4T 1x Edmonton, Alberta thAvenue, T6P 1L Vancouver, British Columbia #24-91 Golden Drive, Coquitlam, B.C., V3K 6R / Binks Manufacturing Company 9201 W. Belmont Ave., Franklin Park, IL Printed in USA 6/93

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