Auto Paint Frequently-Asked QuestionsThis list of questions and answers was generated by makefaq.py, a python script written by Dan York .
The FAQ was written to accomodate a lot of questions asked me on the newsgroups. I can be reached at
FAQ Revised: Wed Mar 21 23:01:44 2001
Table of Contents
- 1. Adjusting Paint Gun
- 1.1. How do you properly adjust a standard spray gun?
- 2. Airbrushing
- 3. Antique
- 4. Automotive Paint
- 5. Bare Metal
- 6. Base Coat Recoat Window
- 7. Base Coat Sandability
- 8. Blending
- 9. Brand Names
- 10. Brush Painting
- 11. CFM
- 12. Can I Do It?
- 13. Candy Colors
- 14. Catalysts
- 15. Cleaning Paint Equipment
- 16. Clear Coat
- 17. Color Bleeding
- 18. Color Change
- 19. Color Codes
- 20. Color Mismatch
- 21. Color Wheel
- 22. Compressor PSI
- 23. Cost of Metallic Paint
- 24. Different Brands
- 25. Fish Eyes
- 26. Flash Time
- 27. Flex Agent
- 28. HVLP
- 29. How Much Paint?
- 30. Isocyanates
- 31. Laquer Gloss
- 32. Metal Flake
- 33. Orange Peel
- 34. Paint Chipping
- 35. Paint Components
- 36. Paint Guns
- 37. Painting At Home
- 38. Painting Plastic
- 39. Painting in Sections
- 40. Pearl Paints
- 41. Peeling Paint
- 42. Polishing
- 43. Polishing fresh Paint
- 44. Preparing for the Body Shop
- 45. Pressure Pot
- 46. Prices
- 47. Priming and Sealing
- 48. Rail Dust
- 49. Reducers and Thinners
- 50. Removing Clear Coat
- 51. Rust
- 52. Rust Inhibitors
- 53. Sandblasting
- 54. Sanding Affects Color
- 55. Sealants
- 56. Sectional Repair
- 57. Shelf Life of Paint
- 58. Single Stage Paint
- 59. Solder and Brass
- 60. Solids
- 61. Stripping Paint
- 62. Swirl Marks
- 63. Technique
- 64. Touch Up Paint
- 65. Tree Sap
- 66. Uncatalysed Paint
- 67. Ventilation
- 68. Vinyl Wash
- 69. Weld Through Primer
- 70. Wet Sanding
- 71. Wheels
1. Adjusting Paint Gun
- 1.1. How do you properly adjust a standard spray gun?
- I'm assuming a conventional suction feed spray gun. An HVLP is a little different. Set your air pressure first. The gauge at the gun should read approximately 55 lbs with the trigger pulled far enough to allow air and not fluid. Point the gun at a piece of masking paper, and pull the trigger a bit further to allow fluid. The pattern should be convex, with slightly more paint in the center than the edges (I'm going to have to put some pictures on my page since this is a commonly asked question). The idea is with a 1/2 overlap, to evenly distribute the material.
- 2.1. 25. Can these same tips be applied to airbrushing? I am trying to airbrush designs on my motorcycle. Please let me know.
- I generally use acrylic enamel (uncatalyzed and reduced to a very thin viscosity) for air brush work, although I admit I don't do much of it anymore. It might be a good idea to get your base color finished with a urethane clear coat so you have a nice base to work with. After you are happy with your design, clear over the acrylic enamel with the same urethane clear. It sort of goes against the rules, since uncatalyzed acrylic enamel SHOULD wrinkle when clear is applied over it, but maybe because it is so thin it doesn't (or at least it hasn't for me). Laquers dry too quickly and plug up on the tip of the air brush, and catalyzed paint cannot be stored. Acrylic enamels are cheap, and you'll only need a few basic (bright)colors to tint with blue red yellow black and white to give you all the colors. Oh yes, one last thing, don't buy tinting colors, buy mixed colors. The tinting colors don't have driers added and may not work properly.
- 3.1. I have a 1928 Model 72 Chrysler that requires painting. I understand the present paint is Duco. Can I obtain this type of black paint?
- Duco is Dupnts old laquer system. It is very inferior to their current line of paint products, so unless you absolutely insist on original paint, use the newer urethanes.
4. Automotive Paint
- 4.1. What type of paints are used on automobiles?
- Japanese Varnish: In the early years, between 1900 and the 1920's, Japanese varnishes were used. The varnish was applied by brush. Nitrocellulose Lacquer: in the 1920's, several paint manufacturers were involved in the development of nitrocellulose lacquers. This paint had rapid drying and low viscosity properties, and was applied with air pressure through a spray gun leaving a hard dry finish in approximately one hour. When rubbed, polished, and waxed, it far surpassed in durability and appearance the qualities of the Japanese lacquers. Synthetic Enamel: In the mid 1930's, a new and completely different type of paint was developed, the alkyd or synthetic enamels. It proved to have superior qualities in film strength, adhesion, lustre, flexibility and durability over all previous paints. The resin base was developed from the reaction between phthalic anhydride and glycerin, with gums, oils and plasticizers added during the manufacturing process a drying oil such as linseed, a polyhydric alcohol, such as glycerine, and a dibasic acid, such as Phthalic Anhydride. It dries by solvent evaporation, like the lacquer paints, but the resin remains soft and sticky when no solvents are present. It cures to a hard finish by absorption of oxygen from the air. The curing process can be accelerated by heat, and several methods of baking enamel were developed. Unlike lacquer, when dry, it needs no polishing to produce a high lustre finish. Acrylic Lacquer: As time passed, chemists developed a substitute for nitrocellulose lacquer, using an acrylic resin as a base. The resins used in acrylic lacquer tend to be slightly brittle. This deficiency is overcome by the use of a plasticizer ( a liquid that is a solvent for these resins and softens them slightly). A cellulosic resin is any resin derived from cellulose (pure cotton). Acrylic lacquer was used extensively by General Motors. Acrylic Enamel: During the late 1960's and early 1970's, technology brought on the development of acrylic enamel, which was harder and more durable. Chemically, it is a cousin to synthetic enamel, but is modified with acrylic resin, and is not soft and sticky with no solvents present. It cures further with the absorption of oxygen from the air. Unlike the lacquers, which remain soluble in solvents, the enamel family is insoluble in solvent when cured. An acrylic resin is chemically any polymer whose basic monomers are chemical derivatives of acrylic acid. Polyurethane Enamel: In the mid 1970's, polyurethane enamel was developed to withstand the severe stress of high speed airplane surfaces, which are subject to rapid temperature changes and flexing. This paint was much more durable than the acrylic enamels. Acrylic Urethane Enamel: Acrylic urethane enamels were developed to withstand environmental elements, such as acid rain and ultra violet rays. It is the most durable paint to date.
5. Bare Metal
- 5.1. I am using R-M Undercoat Zinc Phosphate 834 ZIP over bare metal . The ratio I was given was 1: primer to 1: lacquer thinner #2 and no hardener was required. I was told that you did not have to sand that you could top coat right over it. I was also told that I could paint right over the primer there was no need for a sealer. 1) Do you have to use a hardener for the Zinc Phosphate? 2) Do you have to sand once you apply the Zinc Primer? 3) Do you have to seal the primer before you top coat?
- No, no, and no.
- 5.2. If I take it down to bare metal, then do I need to do a phosphoric acid wash? I know there may be places where I can't get to clean metal and the phosphoric acid will convert rust, but what do I need to do to bare metal? I don't need or want a high gloss surface, just something durable that will prevent rust. What kind of paint would
- Use the acid wash andzinc chromate primer (it is usually green) on the bare metal before you seal and paint. Any of the name brand paints are good quality.
- 5.3. What do i apply over bare metal?
- Use a zinc chromate primer which is essentially a metal treatment. Follow this with a good quality primer surfacer (a brand name that requires a catalyst (urethane or epoxy)). All the major manufacturers use a form of a seven stage process before priming.1. Hot detergent wash to remove grease and oils. 2. Water rinse to remove the detergent, since the detergent interferes with acid. 3. Acid wash to remove scale and open pores in metal. 4. Water rinse to remove acid. 5. Zinc phosphate acid treatment for corrosion protection and paint adhesion. 6. Water rinse to remove acid. 7. Bake dry.This is followed by a primer coat of melamine polyester resin (Japan), polybutadiene (Europe), or a polyester or epoxy ester system (USA).
6. Base Coat Recoat Window
- 6.1. After spraying a base coat do I really only have 30-45 min. to spray the clear coat?
- No, you can apply the clear much later if you like. There seems to be a difference of opinion on the maximum time frame; I've heard anything from 72 hours to infinity. I asked the Dupont techs on their tech line, and they don't seem to know either, and it isn't listed in the technical manual. I've done it three days later with no apparent ill effects.
7. Base Coat Sandability
- 7.1. How come you can't sand a base coat in a BC/CC combination if there are imperfections?
- You can. I usually go over the base coat quite carefully before I clear, and fix any imperfections. You should use very fine paper.
- 8.1. How do i blend paint?
- Good question, since the majority of paint repairs are blends. We will use acrylic enamel for this example (others are similar). After you have repaired the area (body filler, polyester putty, primed, etc.), you must clean the surrounding area with soap and water and a good scrubbing with a final wash solvent (mild, silicone free). I cannot stress the importance of this step enough. It is the singular most important factor in your blend. Clean to the edges of the panel (where the masking starts). After the area is sufficiently cleaned, follow with a thorough compounding of the area (my personal preference is #4 or #2 McGuiars and a wool pad). This will remove old oxidation, and disturb the surface enough to promote adhesion. Clean off any polishing residue. Reduce the air pressure to the gun to around 15-20 psi (siphon feed), and spray the repaired area. Wait for the coat to tack sufficiently, then apply successive coats until full coverage is achieved, slightly extending the coats each time to melt in any dry spray from the previous coat. On the last (blend) coat, reduce the paint in the gun (you may have to pour some out) 100% with blending solvent. Carefully blend out the dry areas. Further addition of blending solvent may be necessary, or if you are very careful, you can lightly blend the edges with 100% blending solvent. ** Note** If you don't have blending solvent, you can use medium reducer, although it doesn't work as well. Don't use fast dry or slow dry solvents, as they contain additives which are not conducive to good blending.
9. Brand Names
- 9.1. What brand of paint should i use for my first attempt at spray painting?
- All major brands of paint perform well and it is not my intent to recommend any one particular brand. However, certain paints are better for the first time painter, although they may have inferior qualities in other areas. A novice or first time painter might try DuPont acrylic enamel (Centari (tm)). It is one of the most forgiving paints, as it dries quickly, melts in overspray well, and does not run easily. These positive features outweigh the negative effects of quick dry times, which are mentioned elsewhere in this FAQ. I don't know if they still make it, but Deltron(tm) by PPG is also an excellent product for a first time attempt.
10. Brush Painting
- 10.1. I've read that automotive paint can also be applied with a brush and with good results. Do you have any experience with this approach ? Can it possibly yield OK results ?
- No. A professional spray gun is an expensive precision tool. With today's mica's and pearls, the finish has to be finer than 320 grit, or the particles will not orient themselves correctly. The paint gun has to provide a fine, even mist to enable the correct transfer of material which may be less than 1 mil (one thousandsof an inch) thick for some base coats. As for applying these coatings correctly with a paint brush there would be a better chance that a random collection of atoms in outer space could gather together to form a Nike running shoe.
- 11.1. My question: What size air-compressor do you need to paint a car? Will a 25 gallon 5hp compressor work for painting that has a 5 SCFM @ 90 psi / 7.5 SCFM @ 40 psi. If so, any limitations? If not, what kinds of problems will I most likely encounter?
- You will run out of air. This will lead to dry spray areas, since you will not be able to paint fast enough to keep the surface wet.
- 11.2. What size air-compressor do you need to paint a car?
- The compressor should be capable of delivering a minimum 20 cfm at 90 psi.
12. Can I Do It?
- 12.1. I am restoring a 65 Triumph Herald an am considering painting it myself. I have never attempted a paint of a complete car. Any suggestions or am I in over my head. The body is straight and I plan to paint it white.
- If you are doing the restoration yourself, you will recieve a great deal of satisfaction in painting it also. All the trials and tribulations will be worth it in the end, and it will be an invaluable educational experience.
13. Candy Colors
- 13.1. I want to change the color to ppg radiance 2 wine berry over pure gold. I used the proper primer and all the steps needed . I painted the door jam areas, the inside of the fenders and under the windshield area with this color. Unfortunately the areas were painted at two different times as my free time would allow. I have discovered I have two different colors!
- Candy, or tri-coat colors must be painted in one step. Unfortunately, you will have to redo the vehicle.
- 14.1. Do i have to use a catalyst or hardener in acrylic enamel?
- You should, to speed up the curing time of the paint. However, acrylic enamel will cure over time by absorbing oxygen from the atmosphere to complete the molecular cross linking needed to create the polymer. The addition of a catalyst accelerates this process greatly (a few days versus a few months without a catalyst agent). Most catalysts contain isocyanates which can be a health hazard if inhaled. A fresh air supply is strongly recommended. And warning labels are often not as adequate as they should be. Methylenedianiline is used primarily as a chemical intermediate in the closed system production of isocyanates and polyisocyanates and is also a curing agent for epoxy resins and urethane elastomers, a dye intermediate, and a corrosion inhibitor.
15. Cleaning Paint Equipment
- 15.1. to clean wash primer out of my paint gun with? It's Corlar 810R mixed with Corlar 815R activator. My brother in law bought the stuff and got me Varsol to clean up with. It just curdled the paint in the gun.
- Most shops use gun wash, a cheap blend of strong solvents used exclusively for clean up. Varsol is not strong enough to dissolve most of the newer paints.
16. Clear Coat
- 16.1. In Panama we have such a humid weather and a high salinity content environment because we are so close to the sea, so all brass pieces, including such well known brands as Baldwin and Period Brass which even have clear coat paint, begin to tarnish and rust quickly. We have not at this time found a good clear coat that will hold up with out turning yellow or even blistering or pealing off so that we can use it as an extra protection for our gold. It needs to be very resistant, even to soap and water stains.
- The expensive and best way is to use powder coating. A less expensive way is to use a product called Egyptian Laquer which is manufactured somewhere in the USA. I'm not familiar with the product, it was referred to me by a paint chemist.
17. Color Bleeding
- 17.1. If i paint it a different color, will the old color show through?
- If the old finish is of poor quality (enamel or lacquer), you must use a sealer to separate the two finishes. Sealer is an inexpensive insurance policy to prevent COLOR bleeding, which was quite common with enamel reds during the sixties.
18. Color Change
- 18.1. Would painting it the same color be cheaper than other colors?
- Of course, painting the jambs, door posts, and underneath the deck and hood will increase the labor hours. Other than that, pigment is the itdetermining factor in the cost of paint. Blue, for example, is made from cobalt, which is relatively inexpensive. Red pigmentsare by far the most expensive, perhaps three times the cost of whites (titanium dioxide).
19. Color Codes
- 19.1. . . . in finding my motorcycle honda CBR1100xx's color which is candy red and coded as (R-101C-U),as i couldn't find it in my country.
- That would be something to discuss with your local paint rep. I try to answer questions relating to application procedures only.
20. Color Mismatch
- 20.1. I bought a white Nissan maxima and have noticed that the color of the bumpers does not match the color of the body. It seems like the bumper is a couple of shades darker than the body. I have noticed this on other pearl white maximas also.
- The flex additive used in the paint on plastic parts often darkens the color. This is quite common, as most of the plastic parts are painted separate. A painter in a body shop will blend the paint from the bumper into adjacent panels to camouflage the change in color.
- 20.2. We just finished painting two front panels with Endura to match the complete paint job done one year earlier in Endura in the same color. When we compared the color the next day, the paint shades between the day old paint and the year old paint were noticeably different.
- Unfortunately it is very common for paint not to match the original finish. If you don't have a tinting system, you'll have to set up the job to blend into the adjacent panels.
21. Color Wheel
- 21.1. What is a color wheel, and what is it used for?
- A color wheel is used to adjust the color when mixing.
22. Compressor PSI
- 22.1. but it only put out about 9 cfs @ 90 psi. Am I nuts to hope to do any painting with a rig like this? It looks like a two stage almost doubles the price. Let's assume I'm not after a show quality paint job. I'm considering painting an old
- You can, but it will be akward. When your pressure drops the paint will not atomize well, and will orange peel. If you wait for the pressure to build up, the paint will dry and you will have dry spots. Maybe if you do it in sections?
23. Cost of Metallic Paint
- 23.1. IS NON METALLIC PAINT CHEAPER THAN METALLIC PAINT?
- No. Metallics are made with the addition of crushed aluminum and/or mica, and is not expensive.
24. Different Brands
- 24.1. Getting to the point - putting a sealer and poly topcoats from one manufacturer on top of epoxy primer(s)/substrate from another manufacturer
- Although the manufacturers may void any product warranty if heir paint is top coated over another manufacturers sealer or primer, they have essentially the same characteristics. The urethane and epoxy based primers are extremely durable, and to my knowledge can be top coated with anything. However, the reverse is not true. Urethane and epoxy paints cannot be applied over some primers (nitrocellulose based lacquers for example). And, the strong solvents used in urethanes can cause sand scratch swelling or feather edge lifting in air dry primers. Of course there are exceptions to this rule (e.g. using urethane over an enamel sealer) but these are special circumstances and I'm not going to get into that now.
25. Fish Eyes
- 25.1. How do you remove fisheyes or water spots that end up in the paint due to the compressor?
- You can't. The affected areas will have to be sanded and repainted. A good water trap is very important when painting.
- 25.2. I have a question referring to fisheyes on paint. What exactly causes it? How can it be prevented?
- Fish eyes are caused by contamination usually containg silicon, that screws up the surface tension of the paint. To prevent them you need a very clean surface and a clean air supply. As a last resort you can use some fish eye eliminator, but use caution since it might result in loss of adhesion.
- 25.3. My question(s) are: 1. What causes fisheye. 2. What do i do to prep the hood for repainting. 3. Is there an additive that will stop this from occurring?
- After sanding, ensure the surface is clean by washing with a final wash like Dupont 4105, and check your air supply. You need a good water trap and clean lines. Acrylic Enamel is prone to fisheye easily. If you must you can use a little fisheye eliminator, but only if you absolutely need to.
26. Flash Time
- 26.1. The term Flash refer to? For example, the directions for paint application say the following: Apply base color to hiding. Flash Base coat 15-30 minutes before clear coating.
- Flash refers to the waiting period it takes the solvents to evaporate from the paint before applying another coat. When using base coat, the paint will look lose it's shine.
27. Flex Agent
- 27.1. i have to paint some golf carts and i was wondering if i should use a flex agent in the paint or will they be okay with out it
- If you cannot bend the parts easily, you can skip the flex agent. If it is bare plastic, you will have to use plastic prep and plastic primer before painting.
- 28.1. I've been looking around at HVLP guns, and my question isn't so much which brand to buy, but rather which type - gravity feed or suction feed. Do you have a recommendation, or pros and cons for gravity vs. suction?
- Gravity feed.
- 28.2. What is the HVLP system?
- A High Volume Low Pressure system designed to increase transfer efficiency by eliminating excessive over spray, which creates high VOC emissions and material waste. They've had a bad rap in the past because the early models didn't work well, if at all, without a sufficient volume of air. Physics dictate that to move a certain volume of mass requires a specific amount of energy. To do it with less air pressure should require a greater volume of air, which should produce the same amount of total energy. Of all the models I've tried, most were poor, some were good, and one was so good I bought it.
29. How Much Paint?
- 29.1. How much paint does it take to fully paint a car?
- It depends on the size of the vehicle, and the type of paint used. There are formulas for sq. ft. coverage, but in my experience are not always reliable. Let's take a 92 Cutlass Ciera for example, which would be a fairly common size. In a base coat /clear coat (BC/CC) application, I would mix 2 quarts of base coat, (perhaps one quart with an HVLP) which thinned to spraying consistency would give me a gallon of sprayable material, and should provide adequate coverage. However, some are more transparent than others, and additional or less material may be required. Paint booth lighting is essential to ensure proper coverage. After applying the base coat, I would mix two quarts of clear, which reduced would give me three quarts of sprayable material (two coats at approx 1 1/2 quarts per coat). An additional third coat could be applied if desired, but be sure to watch for excessive film build which can lead to dulling or solvent popping problems. If you don't have access to a paint mixing system, then buy more than you need. There is no way to fix a paint job that does not have adequate coverage except for repainting the entire car.
- 30.1. I'm wondering about the these two part paints containing isocyanates and hexamethylene diisocynates. Even with a chemical respirator and spraying outdoors I'm getting the impression that it's simply to dangerous for your average car nut to use. Am I stuck with these low budget lacquer primers from Canadian Tire. How much of this isocyanate can one be exposed to before permanent damage results.
- Good question. I wish I knew the answer. Most of the people in the trade have been exposed to a lot more than you plan on, myself included, and most of us seem to have escaped any ill effects.
31. Laquer Gloss
- 31.1. Will I *really* get a high gloss finish by putting say 6 very thin coats of lacquer on ??? It just seems to be building up to a 'satin' finish.
- Lacquer is unique, as it does not undergo any molecular changes when it cures. It dries by solvent evaporation alone. The reason for applying several thin coats is that the solvents may become trapped, and the paint may appear dry on the surface, but will be wet underneath. Also, piling on heavy coats may result in checking problems. Nitrocellulose lacquer, or acrylic lacquer will dry to a dull shine (satin). It has to be polished to get a good gloss. Fortunately, although lacquer has many drawbacks, it is very easy to work with. Apply it, wait till it dries thoroughly, and polish it.
32. Metal Flake
- 32.1. I am soon going to be painting a car with a full flake job, do you know how many coats of clear i should use over the flakes?
- You will have to apply a couple of coats, then sand ou the flake nibs that are above the surface so it is smooth, then re-apply another couple of coats of clear.
33. Orange Peel
- 33.1. I just got a paint job and it came out with an orange peel look over the entire car, what causes that look??
- The paint wasn't reduced to the proper viscosity, or your pressure wasn't right.
- 33.2. I used a Sata gun to paint my car, I used acrylic enamel paint. I have severe orange peel, can you please give me suggestions for making the paint look better without sanding and repainting? It doesn't have to be perfect, just look a little better.
- Unfortunately, the only cure is to sand and repaint.
34. Paint Chipping
- 34.1. Is it possible that slapping, or even hitting a car can cause the paint to chip? What does cause paint chips??
- Paint chips from a loss of adhesion to the substrate. This can occur as a result of several factors. First, poor prep work before painting, inferior product, or sometimes from a sharp impact from a hard object, which might abrade the paint. (Hail does not chip paint, but gravel will). Perhaps if you were wearing a ring it may cause the paint to chip. It is very unlikely that the impact from a hand would cause properly applied paint to chip.
- 34.2. I have a 1990 Evergreen Camaro, the paint is chipping and I have noticed another camaro, same year and color is doing the same. What would cause this so soon?
- Eleven years of rock particles hitting it at 60mph.
35. Paint Components
- 35.1. What are the components of paint?
- All paints consist of pigments resins, and solvents. The resin provides the coating material, with the pigments creating the desired color, and solvents reduce the material to a workable viscosity.
36. Paint Guns
- 36.1. I am a custom painter and would like your opinion about what is the best spraygun
- I'm sorry, but I am not affiliated with any company, I try to remain nuetral.
37. Painting At Home
- 37.1. My question is I have a 1988 Delta 88 which i did some body work to in the garage. I would now like to paint it in the garage. I have plenty of room and not bad ventalation. would you recomend this ,and would the job come out OK?
- No, and no.
- 37.2. i am trying to heat my garage, should i check the surface temp.of the car before painting and what is the lowest temp. you would recommend painting.
- Painting in a garage is very dangerous, and perhaps illegal. There should not be an open source of heat inside the paint room since the atomized paint is very explosive. But, to answer your question 70 to 75 degrees F should be the correct temperature range.
38. Painting Plastic
- 38.1. Is there a specific paint and/or process for painting plastic bumpers? I was advised by a panel beater to sand the bumper using a 400/600 grade sandpaper and then primer it and paint as per usual. Does this sound right?
- Sounds fine, if the bumper you are working on has some kind of existing coating already. If it is bare plastic you will have to wipe it with plastic prep, and spray on a coat of plastic primer or adhesion promoter before top coating. If the bumper is very flexible you might want to add some flex agent to the paint but it is usually not necessary.
- 38.2. My 91 Integra GS Coupe has a black plastic bumper strip all around the car, can those be painted by the paint shop?
39. Painting in Sections
- 39.1. Can I paint my car, a panel at a time, over a period of a few weeks? I've been told that I will experience color matching problems, but I don't understand this if I'm using the same reducing ratios and everything is protected from the sun.
- You can, but there are a couple of drawbacksto painting in this manner. This is an operation where the sum of the parts are greater than the whole. It takes more time to paint individual parts, than to paint the complete vehicle. I would suggest assembling the vehicle first, ( sometimes assembling later damages the paint) and doing some meticulous masking. Make sure the car is prepped to your satisfaction. Get everything ready, and leave the painting for one Sunday. The actual spraying of the car will take you about two or three hours. Then another hour for cleanup, etc. The rest of the day you can spend admiring your work, or wondering how you are going to fix any imperfections that may have occurred.
40. Pearl Paints
- 40.1. Also, he showed me some kind of special paint called Pearl that would make my car looks different in color under different lighting, how does that work?
- Pearl is a material that reflects light (like metallic) but lso allows some of the light to pass though and reflect back from the surface below. The light reflected may be unobstructed, or may pass through another particle of pearl, adding the illusion of depth, and altering the hue. Paints containing pearls usually contain a higher resin to pigment ratio and require more coats of material to obtain full coverage. The newer tri-coat systems involve a base coat, a clear/tint coat, and a final clear coat. This creates a very nice effect, but makes spot repair more difficult.
41. Peeling Paint
- 41.1. What kind of paint won't peel off a while later?
- The technical term is delamination. There are two methods of paint adhesion. Chemical and molecular attraction. Properly prepared surfaces and substrates, and properly applied coatings should have excellent adhesion. Why then, are there so many instances of peeling paint in recent years? The problem seems to be in the quest to meet increasing VOC (volatile organic compound) emissions by using water borne or water based low VOC products. The topcoat should slightly penetrate into the substrate and bite into it with a good chemical adhesion. Unfortunately, this does not seem to be the case when working with incompatible solvents. Notwithstanding all precautions, poor adhesion may result because of faulty product, which happens occasionally. The reps are usually quick to recall it when the problem is discovered, but I remember a few years ago spraying a couple dozen or so that you could peel the clear off in sheets.
- 42.1. i painting my 74 dart sport with centri ultra but someone told me if i put lots of paint on i did when its hard can wet sand all the little mistakes like orange peel and specks of dirt out then buff the shine back i know you can do this with basecoat,clearcoat but i wasn't sure if it would work with acrylic enamel
- You usually can if it is a solid color. If the color has metallic or pearl, you can't because it will disturb the metallic pattern.
- 42.2. I'm a novice at this and need some advise on how to rub out the new paint to get the glossy final finish.
- You will need a 7 grinder (something that runs at about 1000-1200 rpm, no faster or you will have many problems. Panhead wrote and chastised me for neglecting to mention this important tidbit of information), McGuiars #4, #2, #7, #9 compound, a bucket of clean water, a stiff foam sanding block, and some sheets of 8 micron (1500 grit) or 10 micron (2000 grit) wet sandpaper. Do not attempt to polish in direct sunlight. If the paint is non-metallic or clear coated, then wet-sanding is recommended. Do not attempt to sand a metallic paint that has NOT been clear coated as you will disturb the metallic pattern. Wash the car thoroughly. Use 8 micron (1500 grit) or 10 micron (2000) grit wet sandpaper, and fold three or four sheets into three sections so that none of the abrasive sides are touching (from the back, left side in two thirds, right side in one third) and put it into a bucket of CLEAN water. Have a coffee or cold beverage and do nothing for about twenty minutes. This will allow the sandpaper to become soaked and flexible. If you omit this step, you will likely put deep paper cuts into the paint that won't polish out.Use a firm foam sanding block, keep the surface wet and sand the surface, squeezing the water off every once in a while with the sanding block to check for imperfections in the surface. Stay away from edges or high crown lines, as the polishing wheel will burn through these areas very quickly.Once you are satisfied, put a clean wool polishing pad on (if it has old polish on it, then spin the pad and clean it with a dressing tool or something that's clean and not sharp), and apply some #4 McGuiars onto the pad. If you have used 2000 grit to sand the surface with, you might try #2 first. Polish the surface, moving the pad steadily to prevent heat build up (except for lacquer, which can be reflowed). In a few minutes you will see a good shine develop. Continue with the remaining panels. Put on a foam pad, and use #9 , followed with #7 compound, to bring up a deeper shine and eliminate any swirl marks. Wash off any compound residue when finished and have another cold beverage.
- 42.3. It was very icy in the parking lot, and my car slid, scraping against the side of the building. I couldn't have been going more than 5 mph, so the only damage was a white paint stain on the right corner of the bumper. This is my question: The stain, which I assume is ordinary latex or oil based paint, won't come off with soap and water. Is it okay to use paint remover to get it off, or will that damage the underlying car paint?
- Don't use paint remover because it will remove all the paint from your bumper. Use coarse or medium polish, and polish by hand.
43. Polishing fresh Paint
- 43.1. How long would you recommend that acrylic enamel be allowed to dry before wet sanding and rubbed out?
- If you used catalyst, I'd wait a couple of days.
44. Preparing for the Body Shop
- 44.1. How can i (and should i try to) go about preparing the car before i take it to a paint shop.
- I want to be cautious dispensing advice on this subject, since it is easy for someone who is inexperienced to create more work by attempting to do too much them selves. Body shop costs are calculated from the hourly rate the shop normally charges multiplied by the hours required to do the work based on Mitchell Guide Flat Rate manuals. Let's say the hours required to refinish a car is quoted at 23 hours, multiplied by a shop rate of $42.00/HR, plus an additional charge of $19.00/HR for paint materials, we would arrive at a cost of $1403.00 plus any applicable taxes. Body work is extra, usually quoted at the shop labor rate plus an additional charge of $9.00/HR for shop materials. To reduce some of the labor time, one could remove all chrome and trim that has to be removed for painting. If the sheet metal is straight, then sanding with 180 grit or finer would also cut down the labor costs. But then again, putting additional divots with the sander, or denting the sheet metal while removing the trim will only increase the labor hours. I would suggest consulting with the body shop that you intend to use, as to what you can do. How much and what you decide to do is at your own discretion.
- 44.2. I am having my 75 Camaro painted and would like to know if it is necessary to strip paint to the bare metal, also do you recommend removal of all chrome, i.e. bumpers, etc.?
- Yes, if you want a quality paint job.
45. Pressure Pot
- 45.1. I'm planning to use a 2 quart pot, but have no idea what to set the gun pressure and pot pressure to. So far, no one I've talked to seems to know much about this. Have you used a setup like this, and could you give me some starting points for the pressures?
- Start with a low pot pressure, approx. 5-10 lbs, and air pressure at about 40 psi to the gun (this is measured with the trigger pulled). Adjust your fan width so you have an long oval shape (thickest in the center). Overlap 1/2 on each pass. Oh, first do the trouble spots like the wheel openings and edges on the panel you are painting. Don't stop the pass on the edge of the panel or you will get a large accumulation of paint on the edges. The first coat should be light, and don't worry too much about how it looks, although it should be fairly even. Let it tack up to almost dry, and follow with a heavier coat. The first coat will act like glue, and hold the second coat from running. On your final coat ( probably your third or fourth) reduce the paint a bit more and increase your air pressure to the gun slightly and move you hand back a couple of feet from the vehicle and spray a light mist coat in all directions to even out your metallic (I'm assuming you will have a lot of striping). Do this immediately after spraying the last coat or the mist coat won't blend into the paint and will look dry.
- 46.1. I recently bought a 1984 Coupe De Ville. It's in great shape, but the paint is faded and scratched in some places. I was wondering what the cheapest price I could get a paint job for is or how much i should expect to pay.
- You'll have to check with your local area shops to find who is the cheapest, but remember, you get what you pay for. Quality paint materials are expensive, and are not used on cheap paint jobs.
47. Priming and Sealing
- 47.1. I plan on re-painting the entire truck the same color with acrylic enamel. I'd like to know if I'll get good results without priming or sealing the entire truck, with exception to priming the repair work....also what should go onto bare metal?
- If your prep work is good, you shouldn't have a problem. Use some etch primer on the bare metal areas (you can do this in the booth just before top coating). I would recommend a quick coat of sealer though, as it is cheap insurance.
48. Rail Dust
- 48.1. I'm having problems with the paint on my '97 Dodge Ram pickup. All over the exterior (mostly lower exterior) there are these small pin head size rust spots. The color of the truck is white and these spots really stand out. I've tried everything under the sun to get ride of the rust-paint cleaners, clay bars, etc., etc.; and I get them off and apply wax, and a month or two later they're back.
- Good question, and one which may have several causes. First, it may be environmental. Since it is confined to the lower part, do you drive near an industrial manufacturing area or a rail yard. Fine metal particles may be on the ground, and may cling to the car, rusting when they get moisture. It could be a problem with the paint (I've known of cases where the paint can lining dissolved and contaminated the paint). And then again, I've seen cases where someone has cleaned the chrome on their vehicle with steel wool, and the particles of steel wool that cling to the car rust. Sorry I can't be of more help.
49. Reducers and Thinners
- 49.1. What are reducers or thinners and why do we need them?
- Aliphatic hydrocarbons (Mineral Spirits- V M P, Naphtha) Aromatic hydrocarbons (Toluene, Xylene) Esters (Ethyl Acetate, Butyl Acetate) Ketone (Acetone, Methyl Ethyl Ketone (MEK)) Various combinations are used along with other additives (retarders, accelerators, and levelers) to reduce the viscosity of the material to a sprayable consistency and accommodate climatic conditions. In general, the smaller the molecular size of the resin (high volume solids), the less reducer will be required. Some products require very little or no reduction. I recommend following the manufacturers directions unless you have extensive experience in spray painting automotive finishes. However, in a pinch, the general rule is that reducers are downward compatible (i.e. you may substitute acrylic enamel reducer for enamel reducer, but NEVER vice versa. The solvents are weaker and you'll end up with an ugly curdled mess in the bottom of the paint gun).
50. Removing Clear Coat
- 50.1. the cab and the hood--in these areas it is chalky looking where theclear coat is broken down..the color coat is good enough that I would besatisfied if there was some way to remove the clear coat and re-coat thecolor coat
- No. You will have to sand everything off.
- 51.1. What causes rust?
- Corrosion is caused when an area of metal has a positive charge and another has a negative charge. Water acts as an electrolyte, allowing current to flow between these areas. During this process the metal absorbs oxygen from the water and forms iron oxide (rust). Salt water conducts electricity better than fresh water so in areas that use salt on the roads, this process is greatly accelerated. The objective of applying a protective coat of paint is to insulate the metal from water. To ensure that no rust is present before we coat the metal, we clean the metal with an acid (phosphoric based, which leaves a thin film of iron phosphate or zinc phosphate that prevents flash rusting), and then apply a zinc phosphate coating which neutralizes the acid, and promotes primer adhesion. Zinc (galvanized and zinc rich primers) competes with the iron for oxygen, and becomes the sacrificial metal which corrodes, leaving the iron undamaged.
52. Rust Inhibitors
- 52.1. There are two small rust spots that i need to scrape and paint. I got this spray called Defender II Corrosion Converter. It's used on pipelines and is supposed to convert rust to a protective coating. I was wondering if this would be a bettter primer than rustoleum or if i should put rustoleum over it
- As for the rust, it should be removed completely (usually this requires some sandblasting). The conversion coatings only work to the depth they penetrate, and some rust may still exist below the converted coating. It appears you are looking for quick fixes, and there aren't any.
- 52.2. I did not see any mention of using products such as Rust-Mort or POR-15. These products are used on pitted rust areas where it is next to impossible to get all of the corrosion out.
- These products promote a rust conversion process. Most contain some phosphoric acid which reacts with iron oxide (rust) which is chemically converted to an inert material. Sold under many different brand names, they are a common product on auto body shop shelves.
- 53.1. I have sandblasted the underside of my car and was told to go ahead prime right after a good sandblast job.Is that ok
- Sure. But I'd suggest you sand with 180# to clean up the metal just to make the prep work a little easier.
54. Sanding Affects Color
- 54.1. . . . I intended to color sand and buff out. Unfortunately this didn't work. As soon as I used the 1500 grit paper the color changed dramatically...to something MUCH more orange.
- Some red colors are notorious for pigment separation. I don't know why, but to my knowledge, it is something that affects only the reds. Sort of reminds me of the time I decided to wet sand a small spot of Martin Senour etch primer before I painted a quarter panel. The technical notes said in large capital letters, but I did anyway since it tends to load dry paper. Nothing happened. What the heck do those guys know anyway? I blended in the repair. The next day there was a large green stain in the orange paint. It turns out that the etch is acid based, and likes water, so the green pigment was free to bleed through to the surface. Seems those tech notes are worth reading after all. Anyway, back to the red problem. If you're not sure, lay a couple of coats of clear over the paint. That will leave you some meat to sand (just don't go through to the color), and it polishes nicely.
- 55.1. I bought a new Ford F150, the dealer recommended that a Royal Guard protective paint coating be applied at a cost of approx. $400. What is your opinion of this and are there other options available or required to protect the paint of one's truck that will probably seldom be waxed?
- Save your money.
56. Sectional Repair
- 56.1. My question is I am replacing a rusted out quarter panel in the rear of my nova. I have been told that after welding all that needs to be done is sand down the weld line and bondo over it. So the real question, will this blend well with the rest of the car and do you have any idea of what type of welding rod to use, and the type of bondo
- That is the basic procedure. Remember tig or mig welding as acetylene will create warpage problems. I recommend letting the pros do this type of repair as there may be legal and safety concerns.
57. Shelf Life of Paint
- 57.1. How long can you keep unmixed paint after you have opened it?
- It depends on the type of paint. Some paints (urethanes or epoxies for example) do not depend on air to cure, so they will store well, in some cases indefinitely. Other types such as enamels utilize the properties of air to cure (solvent evaporation and oxygen to induce cross linking) and have a relatively short shelf life.
58. Single Stage Paint
- 58.1. I recently had some painting done and the painter said he would use a one step process. I gather this eliminates the need to clear coat. In your opinion does this process provide a finish which is as hard and durable as paints that you would use with a clear coat.
- They are one and the same, except the clear doesn't contain any pigment. Color Changes
59. Solder and Brass
- 59.1. have body soldered some parts and metal/resin filled other parts of the bodywork. Is there anything that should be done to stop flux/acid reactions.
- Soldering parts is not something that is done often. Like brazing, the flux and the electrolysis between two different metals creates problems, usually affecting the adhesion of the body filler that covers it. Try and clean the area well before using metal prep and etch primer to remove any trace of the zinc chloride flux, although I can't honestly say what effect, if any, it will have on any coating applied over it.
- 60.1. What does the term volume solids mean?
- On the technical data sheet, volume solids refers to the percentage of actual film formers in the paint. The remainder is lost to evaporation. (e.g. 32% solids means that 32% of the material applied forms the coating; 68% is reducer or thinners).
61. Stripping Paint
- 61.1. What is the best and quickest way to strip the paint off of a car?
- The most common methods of paint removal are sandblasting, plastic blasting, chemical stripper or sanding. Sandblasting is not recommended as the high energy tends to create heat and warp the sheet metal, which creates a whole new set of problems. Plastic blasting is good, but expensive. Chemical stripper is fairly inexpensive and fast, but it is quite messy and be sure to mask or remove all the trim and plastic lens coverings. Additionally, caution must be used to avoid skin or eye contact which could result in severe injuries. A dual action sander (set to strip mode) with 80 grit paper will do the job nicely, although it may take a while. Follow with 180 in oscillating mode to remove the circular patterns in the sheet metal.
62. Swirl Marks
- 62.1. The previous owners of our car at one time washed it and apparently didn't rinse off all of the residue...therefore, on the hood there are definite swirl parts where they had wiped and the residue etched into the clear coat paint. The underlying paint seems to be all there. Is there anything that can be done to resurface the clear coat to make it look factory new again?
- Residue from hard water, unrinsed soap or dried wax or polish, usually require power polishing to remove. If you haven't had experience doing this yourself, I suggest speaking with the local auto detailers. A polisher can cut through the paint on the crowns rather quickly which will mean a trip to the body shop for some expensive repairs.
- 62.2. I have a black dodge it has a lot of marks on it. What is there that will take them out
- If the marks are not too deep, you can sand them with 2000 grit wet sandpaper, and polish them out.
- 63.1. What is the basic technique of spraying?
- You're in the paint booth, and you've used compressed air to blow dust from the panels, edges, beneath the moldings and lights, and from the masking paper and the wheel covers ( You do this outside the booth first, then again in the booth with the exhaust fan running, starting furthest away from the fan). You then have washed the vehicle with a Final Wash or Prep Wash (other washes contain silicone which cause fish eyes). You finally wipe the vehicle with a clean tack cloth and you're ready to spray. Occasionally, even after reducing the paint to the manufacturers specifications it may be too dense to spray properly. The usual specs is about 15 seconds in a #4 Ford viscosity cup. Translated into English, that means about 4 seconds to stop dripping off the end of the stir stick. Turn your regulator to about 50 lbs, and get a nice oval pattern. Trigger the gun so that air passes through the cap, but no fluid comes through. Holding the tip of the gun about 8 - 10 inches perpendicular to the surface, start your pass along the panel at a hand speed of about one foot per second and squeeze the trigger to allow fluid. At the edge of the panel, release the trigger to stop fluid but still allow air. This constant air flow ensures that the air is not pulsing with bursts of pressure. This could cause excessive build up at the ends of you pass, leaving runs and sags. Don't stop at the edge of panels either, as this will also cause build up of material. On the back stroke, overlap half the first pass (the edge of the paint should appear dry, and the center wet. This is known as a medium wet coat), triggering the gun as before. Always begin painting furthest away from the exhaust fan, so that you are painting over the overspray. Otherwise, overspray will settle onto the painted areas and may not blend in, leaving the surface dry and dull in appearance. With base coats, wait until the coat of paint is DRY before applying the next coat. Otherwise wait until it is almost dry, but a little sticky (the directions are usually close). If you get runs, drips, sags, don't try and fix them while you are painting. You will likely create more problems. They are easy enough to repair after the paint has cured.
64. Touch Up Paint
- 64.1. Recently I went to an automotive paint supply and asked about repairing a small area of damaged paint on my car. They said they could put acrylic enamel in an aerosol can for me but it would only contain pigment and solvent no hardener. I was told that if I used it in conspicuous place it would be highly noticeable due to the fact that it would never be glossy nor could it be buffed. My question is why sell the product this way and could I , in your opinion, use this method on an 8'' x 8" section on a fender and get decent results? How come no catalyst in these cans?
- When catalyst is added to paint, the paint cures very quickly. In a few hours it would be have the consistency of Jell-O, and in a few days it would be rock hard. At any rate, you would have to use the paint within a couple of hours at best. Acrylic enamel will cure without hardener by absorbing water vapor from the atmosphere, but the process is very slow. I don't know if you would be happy with the results of painting a section of a fender with a spray can. The paint is quite thin, and will require many coats for coverage. The edges will be dry, and the color probably will not match. It seems like a small job that your local body shop shouldn't charge too much for.
65. Tree Sap
- 65.1. Due to limited space at home I park my truck beside the garage. This causes my truck to become spotted with tar or pitch from the pine trees. How can I clean the pitch off my truck without damaging the paint. Also what type or brand of wax would be best to protect the paint and make it easier to clean when needed.
- Warm (on the hot side) water and dish detergent seems to work the best for tree sap. As for the waxes, most of the main brands are good.
66. Uncatalysed Paint
- 66.1. Are there any one part paints - as in the days of old - that you would recommend? Some of us have older cars that we want to maintain but the current paints (base coat, top coat, and curing agent) might be beyond us - in skill and safety.
- Acrylic Enamel is still used these days. It is recommended that you use a catalyst, but is not absolutely necessary. Fairly easy to work with, and most of the newer colors are available with the exception of some pearl and/or mica colors.
- 67.1. What do you need in the way of ventilation?
- Nearly all the materials used in automotive refinishing are hazardous to your health, the paint especially so. The catalysts usually contain Diisocyanate Prepolymer, and it's the that is the main concern. It attacks the central nervous system, and can cause permanent injury. A good air flow, and a fresh air mask should be used. If you don't have any bronchial problems, then an activated charcoal mask can be used. I have used the charcoal mask for years, but now my lungs seem to have an asthmatic reaction to the fumes and I strictly use the fresh air system. Also, some paints contain lead, which may have negative effects on your health when painting or sanding,
68. Vinyl Wash
- 68.1. One question I have now is the use of a so called vinyl washand how it fits into the prep sequence. How does it compare to a self etching primer? Do I have to prime after the use of vinyl wash? Do I need to use metal wash as well?
- Vinyl Wash primers are used over properly prepared bare steel. The basic function is to promote adhesion of the paint to the steel. Metal wash is a low concentration of phosphoric acid (sometimes with fluorides) that is wiped onto bare steel, and removes oxidation and slightly etches the metal. The vinyl wash primer is sprayed on after, and followed with a primer surfacer. The metal etch wash (that is wiped on) goes a long way, as does the vinyl wash primer (since it is used only on bare steel and applied lightly as it has no filling qualities). There is no need to buy large quantities of either. Of course there are other uses for the metal wash like cleaning mineral deposits from the kitchen taps (phosphoric acid cleaners are often sold under trade names such as CLR). You really can't skip the metal wash sequence over bare steel or the primer surfacer will have poor adhesion.
69. Weld Through Primer
- 69.1. Most of the rust on my car is between the sheetmetal joints that were spot-welded together. I've drilled out the spot-welds and removed the glass and I'm removing the rust, but when I get ready to weld the sheetmetal back together, I don't know how to protect the areas where the sheetmetal is sandwiched together. I'm concerned that the heat from welding will burn away any protective coating I might put on the metal leaving me with a worse problem than the one I'm trying to cure. Any advise?
- Use weld-thru primer.
70. Wet Sanding
- 70.1. I am looking for something that will teach me how to wet sand the car including all the steps and so forth. Got any places to look?
- Wet sanding involves using a specific type of sandpaper. The benefits are less loading of material in the paper, a better visual view of the sanded area (the sanding dust is rinsed away), and allows the use of a much smaller grade of sandpaper than dry sanding (anything over 400 grit tends to load the paper almost immediately). The drawbacks are that is is a bit messy, and that the surface has to be thoroughly dried before painting, as water can become trapped in seams and moldings. Wet sanding isn't very complex. Water, some 600 grit wet paper and a lot of elbow grease. Sand until you don't see any orange peel (it shows up well when the water dries) and small imperfections are feathered. Use the block to squeegee off the excess water. If the water you are using has a high mineral content, don't let it dry on the car. It could leave spots which may bleed through the new paint.
- 71.1. How do you paint wheels on a car that has a coating? What types of paint are used to resist the paint coming off?
- Usually the wheels are sandblasted to bare steel, then primed with etch primer, and painted with acrylic enamel or bc/cc.
Copyright (c) Bob Story