How To Paint Your Car Start To Finish
Now, as far as how much you thin the paint is concerned, FOLLOW THE DIRECTIONS ON THE LABEL. In fact, before you use any automotive paint product, read the instructions on the can thoroughly and follow them to the letter (especially if they disagree with what we say here!). Paint companies know their products and how they work best; furthermore, in recent years companies have had to alter products numerous times to meet changing environmental regulations and other factors. Always read the directions. Need we say more? The amount of thinner you must add to the paint is not a variable. If your acrylic lacquer says to add one part of thinner to one part of paint, do exactly that. You could use a measuring cup, a stirring stick marked in proper proportions, or a large coffee can with evenly-spaced “rings.’ It’s usually easiest to pour the paint and then the thinner, into a large third container for mixing. I mix about two quarts at a time– enough fo fills the gun twice, which usually allows one or two coats on the car before having to stop and mix more paint. After the paint and thinner are mixed, strain it as you fill the spray gun cup.
The variable is the type of thinner you use. I don’t mean what brand or quality–you must use acrylic lacquer thinner in acrylic lacquer paint; use best-quality thinner for color coats; and preferably use like brand products in conjunction with each other. I mean what speed of thinner. Most paint manufacturers offer “fast,’ “medium,’ and “slow’ reducers for each type of paint. The speed of the thinner determines the drying rate of the mixed paint, once it’s sprayed on a surface.
This, in turn, determines the amount of “flow-out’ or gloss the finish will achieve before it “sets up’ or air dries. For primers and undercoats you usually want a fast thinner because :
(1) you don’t need a glossy finish,
(2) you don’t want the solvents to penetrate and soften possible underlying layers, and
(3) you want the undercoats to dry quickly so you can sand them and apply more coats.
For your top coats, however, you must carefully choose the correct speed of thinner to adjust paint flow out to the temperature (primarily) and the humidity (secondarily) in the painting area.
Since weather changes, any serious painter should always have a good supply of all three speeds of thinner on hand. Thinner is relatively cheap, and if you do much painting, you always need it. Secondly, you should have a thermometer in your garage. Third–and this is a luxury that amateur painters enjoy–do your painting when the ambient temperature is between 70 and 85 degrees, if at all possible. Then, you should be able to look at the paint label for the recommended speed of thinner to use (in fact, your paint supplier can probably give you a temperature/thinner speed chart from the paint company).
This is a starting point. From here on it’s up to you to juggle the variables, test the spray pattern, and develop the “touch’ and combination that works best for you. In terms of thinner speed, you want the color coats to spray on “wet’s that is, without much overspray, and certainly without the paint drying in the air before it gets on the surface. But you want the coats to flash dry before they start to run, or wrinkle underlying layers from solvent penetration. Lacquer paint isn’t nearly as critical as enamels or urethanes since it doesn’t run easily and you’ll be sanding and rubbing the finish to make it glossy later. For beginners, the major concern is to use a thinner slow enough to reduce overspray or dry spray, and that gives the paint time to let solvents evaporate through the surface. It is also important to spray lacquer wet enough that the paint fully adheres to the underlying layer.
Once you begin to paint the car, if you have a dry spray or overspray problem, mix your next batch of paint with slower thinner. This is one good reason for mixing small quantities of paint at a time. What if you’re already using the slowest thinner? There is an additive called “retarded’ which you can add to any mixed paint to slow drying time, but I don’t recommend it. Instead, paint on a cooler day or earlier in the morning. However, the thinner might not be the problem.
MASKING THE CAR
When we last left you, the vehicle was painted under the hood and trunk and inside the doorjambs, with the outside sanded and ready to paint. All you need to do now is lightly sand down any overspray on the exterior from the “jamming,’ mask the car, and paint it.
Most of the car should be stripped so there isn’t much left to mask. The job is straight forward–use tape and paper to cover everything you don’t want to paint on. My best tip is to use good-quality tape. Cheap tape that won’t stick, especially to window rubber, is frustrating. My preferred brand is 3M, and 3/4-inch is the common width (narrow enough to bend around corners easily). The second tip is to attach the tape to the paper first, along one edge, then attach both to the car. Most paint manuals stress using masking paper (available in rolls at the paint store), but I have used newspaper for years without a problem. It’s wider, you don’t have to cut it, and it’s free (I’m cheap). Masking paper is less absorbent, and it fits paper-and-tape dispensers. If you want to go first class, get one of these–it makes masking much easier. Maybe if I had one, I wouldn’t hate this part of the job so much.
The second tip is to attach the tape to the paper first, along one edge, then attach both to the car. Most paint manuals stress using masking paper (available in rolls at the paint store), but I have used newspaper for years without a problem. It’s wider, you don’t have to cut it, and it’s free (I’m cheap). Masking paper is less absorbent, and it fits paper-and-tape dispensers. If you want to go first class, get one of these–it makes masking much easier. Maybe if I had one, I wouldn’t hate this part of the job so much.
A few other hints. Masking around tight corners with paper can be difficult. In such cases you can mask around the edges with tape alone, then go back and mask with paper to the tape. This is called double taping. If you want to keep over spray out of an area such as a doorjamb or hood seam, tape along the edge of the body so half the tape protrudes, fold the tape back so half the sticky side is out, then close the door or hood.
This is called back-taping. It’s usually not necessary with lacquer. Tape holes in the body (i.e., where a door handle or aerial is removed) from the inside to keep paint out. If you don’t want paint on the undercarriage, you can hang paper down from behind the rocker moldings all around the car. And, of course, don’t forget to cover the wheels and tires. Your paint store sells ready-made “skirts,’ but you can use paper and tape.
Photo: HOW TO MASK
- Once the car is blown off and in the garage, it’s time to mask it. A masking machine like this (or a smaller version) is very helpful.
- However, you probably don’t have one. If not, blow off an area on the floor, roll out and cut off the masking paper, then tape a strip of 3/4-inch tape to one edge, letting half stick to the floor.
- With tape thus attached, use paper to mask the stuff you don’t want paint on.
- Be sure to seal the edges of masking paper anywhere it overlaps, and flatten and tape down folds. Otherwise, overspray “dust’ can collect in the paper and blow out during later coats.
- Beginners often find it easier to mask along a molding (especially rubber) with tape first, then go back and attach the pre-taped paper to the tape. This is called double tapping.
Photo: After masking, wash down the whole car with wax and grease remover, working in small sections and drying it with a clean towel. Avoid touching the surface with your hands after this.
Photo: Just before you’re ready to paint, go over the surface with a tack rag. John uses the gun to blow off dust at the same time.
Photo: The last step before shooting the color is to spray on a coat of clear sealer. Note the cloth wheel “skirts’ and the fact that little masking is needed.
MIXING THE PAINT
It’s the next morning. First thing, blow off the car with an air gun, being sure to get any dust or debris out of seams, vents, and so on. Then go over the whole car again with a good, fastdrying wax and grease remover, applying it and wiping it off in small sections, as directed on the label. Then go over the surface with a tack rag (get some at the paint store) to pick up any remaining dust or lint.
If you are having problems with dust in your garage, here are a few more hints. First, disconnect both battery terminals in the car. Second, hang one or more chains from the frame onto the floor. Third, try a new product from Ditzler called Stat-Free (DX-102). You mix it with alkyd reducer, mist a coat over the whole car, tack the car off, then go back and mist on another coat, and your car won’t have any “static cling.’ In the chapter on paint products we discussed sealers. If there is some old paint under the primer on your car, I’d strongly suggest using a sealer to guard against color bleed-through. If you stripped the car of old paint, a sealer is still wise to help the color coat adhere better to the primer. Since you have already sprayed the doorjambs, you need a clear sealer such as Ditzler DL-1947 for lacquer. In any case, use a sealer recommended for the top coat you’re applying, and compatible with the undercoats. Most sealers come ready-to-spray and cannot be sanded. Apply it about half an hour before painting the car (or per directions on the label).
Photo: MIXING THE PAINT
Prepare an area on a bench or table to mix paint as you go. Read label on can to determine reduction percentage. Stir paint, and pour about a quart into a clean, larger container.
Here’s one easy way to measure for thinner. Dip stirring stick vertically to bottom of can to measure depth of paint (line 1); multiply this length by reduction percentage (i.e., 150 percent, or 1 1/2 times), and add this length above paint line. Mark the stick here (line 2).
Stand the stick vertically in the can and pour in thinner until level reaches the mark. See text for type of thinner to use. It’s important.
Stir paint and thinner, then strain it as you fill the cup.
ADJUSTING THE GUN
Different paints recommend different at-gun spraying pressures, plus you must adjust the pressure slightly from this recommendation to get the best spray pattern. A small adjuster at the gun (arrow) works best; one with a dial gauge helps the beginner start in the ballpark.
Most painting is done with a fullwidth fan pattern (top). For small areas, turn fan control knob (1) in; to reduce runs, you usually need to reduce paint flow, as well (knob 2), and reduce air pressure. Note built-in pressure gauge (3) on this Sharpe gun. Sharpl
Before you spray on the car, test the gun pattern on another smooth surface. Pull the trigger for two seconds. The pattern should look like this.
Then make a pass left to right. The thin coat should be even top to bottom.
If your test pattern looks like this (split spray), try reducing the air pressure or fan width. But more likely the gun or cap needs cleaning or repairing.
If this happens, you’re probably moving the gun too slowly; or the pressure may be too high, the fan too narrow, the thinner too slow, or any combination of these. Readjust and practice.
If you can’t spray like this on a test panel, don’t even think about spraying the car yet. Overlap passes 50 percent, as shown, for single wet coats.
Photo: Ready to spray? Hold gun about 8 inches from surface–usually a hand’s width–and keep it parallel at all times.
Photo: Also keep gun, as viewed from top, perpendicular to surface; that is, don’t swing gun in an arc during pass, as shown here.
Photo: Once you start spraying, always keep gun the same distance from the surface, move it at the same speed, keep passes the same length, and overlap the same amount. Be steady and consistent. Be sure to keep the hose and your clothing off the fresh paint. John ties rag around top of cup to ensure against drips.
Photo: Start at the top, and work around the car. Here John has painted the roof, hood, and left fender; he’s starting on the right fender, will move to right side, trunk, and end on driver’s door. Don’t forget to spray inside fender lips, under all edges–coat all surfaces evenly.
Photo: Not bad for a couple hours’ work. With practice, and especially with lacquer, the spraying becomes the easiest part. Enjoy the burger, John, and let the car sit. Next month we’ve got more work to do.
How To Paint Your Car
But before you can spray the paint, you must first mix and reduce it. Stir the contents of each can. Then blend all cans of paint to ensure color uniformity can-to-can. Get an extra, empty can to do this, and do it before you thin the paint.
If you have these things dialed-in, spraying the car shouldn’t be difficult. Don’t get nervous. The trick is to spray in a steady, even, and most importantly consistent motion. Always hold the gun the same distance from the surface (about 8 to 10 inches), do not tilt the gun up or down (keep it parallel to the surface), and do not swing the gun away from the surface at the beginning or end of passes. A “pass’ is however far you can comfortably reach in a right-to-left (or vice versa) movement of the gun, usually 3 or 4 feet.
For spraying lacquer color coats, most painters recommend spraying “single wet coats,’ which means making one pass left-to-right, then moving the gun down half the width of the spray pattern, and making a pass back right-to-left so that the two passes overlap 50 percent.
Move the gun down another 50 percent, make the next pass back left-to-right, and so on. Release the trigger at the end of each pass. When you start a new panel, overlap the edge of the previous one by about 6 inches. The object is to cover the car with as uniform a layer of paint as possible, on each coat.
As long as you keep the spray gun equidistant from the surface at all times, the only variable in the spraying process is the speed, or rate of movement, of your “pass.’ Moving the gun quickly will give a thin coat of paint; moving it too slowly will “load up’ the surface and lead to runs or sags.
The only way to learn how to move the gun is through practice–and that’s why I told you to start practicing with the spray gun months ago. We can’t tell you how to do it. Most painters have slightly different “styles’ anyway.
The clue is to be smooth, consistent, and systematic. Follow a pattern as you spray the car, working basically from top to bottom. Always move from one panel to an adjacent one as you progress around the car, so that you keep spraying next to the wettest paint. For instance, you could start with the roof, move to the hood, then do the right front fender, right side, trunk, left
For instance, you could start with the roof, move to the hood, then do the right front fender, right side, trunk, left side, and end up with the left front fender. How many coats you apply at once will depend on your “style’–how much paint you apply with each pass. But with acrylic lacquer, you can generally apply two or three coats in succession; that is, go completely around the vehicle three times before stopping to let the paint set up and to mix more paint.
Wait about 20 minutes, do the same again, and then repeat once more after another 20 minutes. Some people call this three coats of lacquer, some call it nine. That’s irrelevant since the quantity of paint applied is what’s important. Experts say the total paint thickness (including base coats), after sanding and rubbing, should be about 4 mils (a mil is about the thickness of a celophane cigarette pack wrapper). But how can you measure that? We also said an average car takes about 5 to 6 (maybe 8) quarts of unreduced lacquer to paint the exterior. But what’s an average size car? And how much will you color-sand back off to get it smooth?
How much paint to apply is something you will learn to judge from experience . . . especially from the experience of rubbing through the paint in the final step (which we’ll cover next month).
My rule of thumb is: always use the minimum amount of paint practical (this includes primer)–enough to cover completely and evenly, and allow for at least two color-sandings and rubouts. This will give you a little insurance during the first rubbing process, and will allow you to “renew’ your lacquer job with another rub-out sometime down the road. The important point, though, is to avoid the thick, “40-coat’ lacquer jobs custom painters once boasted of. Thick layers of paint–particularly lacquer–may sand down smooth and mirror-like, but within no time they’ll be cracking, splitting, checking, peeling, and otherwise turning to junk when exposed to the elements.
That’s the basics. Load your gun and start shooting. The rest you must learn by doing. One last word of advice, though. If something does go wrong– and there’s an odds-on chance it will– stop painting. Assess the problem. See if you can “adjust’ something to solve it. Sand down the messed-up area. Then start again. Repeat as often as necessary to get it right. You can always fix it. That’s the beauty of lacquer . . . at least one of them.
Photo: If the car is finally ready to spray, it should look like this: disassembled, bodyworked, primered, block-sanded. The first step is to blow all dust off the car and out of every crevice. Do this outside the painting area.
Photo: Our painting example is a neglected ’66 Nova SS 327/350 hp picked up by Reggie Jackson and being restored by John Harvey (Reggie’s Paint by Lil’ John, Costa Mesa, California). This is how it looked two weeks ago.