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Article: The DIY Paint Job
|Symptom: You want to paint your own
car; you want to know what it takes to paint your own car; you need to
be talked out of trying to paint your own car.
“I want to paint my own car, can you tell me what's involved?”
First of all, like many of my articles some pre-preaching. I firmly believe that there are only two ways to paint a car. One is to do it the right way, to use all the right materials, methods, tools and techniques. The other way is just cover the car with a substance that makes it a different (or same) color and do that as cheaply as possible. There is no in-between. And yes, the latter of the two methods is probably cans of Krylon spray paint, or whatever brand is on sale.
Why do I believe this? Because anything less than the "right way" (proper materials, tools, techniques, etc.), isn't going to last all that much (if at all) longer than the "Krylon" method. Perhaps that isn't true in every case, but if you can paint a car with a rattle can for $30, or you spend $150 for some off brand auto paint and a borrow a compressor and spray gun, and use no primer, and get oil and water in the air you use to spray it, and don't mask off what you should; it isn't going to be 5 times better than the $30 Krylon job. You either do it all right, or just go the cheap route.
And I'm not undermining the spray paint job. It may meet your needs, you may read this article and take away many techniques that you could use with the department store rattle cans. I really think with enough preparation, the Krylon job could be done to look halfway decent. Certainly isn't going to last long, but it might look ok. But if you go any further, you must go all the way in my opinion. Spending good dough on auto paint, but not doing the right prep, or using the right gun, or not taking off parts you should, is a travesty in my book.
And while this article will find its primary home at my own VW Beetle Restoration website “The BugShop”, there is really no Beetle, or even VW specific stuff in here. For more Beetle particulars, as well as other important info on painting, I encourage you to explore my website, in particular the last two articles on “Doing a #4 Resto”.
But to start here, let me give you
some background. My “Painting Resume” if you will.
For what it is worth, only the last two efforts above are the right way. In hindsight, the first three might just have well been cans of Rustoleum, and I would have had a lot of money left over to buy other neat VW stuff. But "can I do it the 'right' way myself?". Sure you can. If you invest the $$ in the proper tools and materials, invest the time to learn the techniques, have access to or own the proper environment AND set your expectations accordingly, you can do it. This article is about how I "did it myself".
I bought my '85 VW Cabriolet in 1993, it had 96,000 miles on it. Over 7 years, I did all of the maintenance, put a new top on it, made a few mods along the way, and basically loved driving it. But in 2000, with 225,000 miles on it, the body was looking pretty tired. New England winters were taking their toll on the body (as had an old lady in Ford Explorer at my church, numerous shopping carts and bikes, an as-yet-unidentified vehicle and, yes, me). And in one bizarre incident, after replacing the reverse light switch (left the car in reverse) and an emergency brake cable (left the emergency brake off), I reached in through the open passenger window and started the car..... and proceeded to watch it back all the way through the closed garage door behind it. The car needed help, one more salty winter and the body was going to be beyond help. Bubbly "cancers" were starting to show on the doors. The lower corners were getting the traditionally brown-orange rust color. I had to do something...
I resolved that due to my financial situation,
I could not afford to drop the car off at Tom's shop again and contribute
another $2500-$3500 towards his retirement. Of course if I did, it
would look great, but the first time I passed the salt truck this winter,
I would hate myself. So resolved to take what I had learned doing
my Beetle and hanging around Tom's shop, reserve a long weekend and paint
the car myself in my garage. I would do the best job I could, and
be happy with the results, whatever they were. This was critical.
"I will be happy with the results, whatever they are." "I will be happy
with the results, whatever they are." "I will be happy with the results,
whatever they are." "I will be happy ...................
So let's get started. This article
will discuss different areas of materials, tools and techniques, then will
go into the specific steps I used. The fact that my car was a water-cooled
VW is pretty irrelevant here I think, the techniques could be applied to
any vehicle. Just below is a hot index if you want to jump to a specific
About the Paint
Believe me, I am just a cheap as the anyone. If I'm going to pay $80 for a quart of paint, I better know what it does, why it is so expensive and what my alternatives are (competitors selling for less?). Real auto paint is expensive, that is just a fact a of life. Get ready for some serious sticker shock when you go to the autobody supplier. Automotive finishes are a science, that is, "measurements of polyurethane microgel deposition and clearcoats with the oscillation technique to determine the viscosity-temperature behavior correlate well with technical properties of the final films". Huh? Well, I am not an expert, but here is some of what I have learned:
In the beginning there were lacquers, they usually needed to be rubbed, polished, and waxed to have a good luster and shine. Then came Synthetic Enamels. They had a resin base as opposed to a nitrocellulose one. This resin benefited from heat-accelerated drying, or it would remain soft for a long time. It needed no polishing. Acrylic lacquers came next, which used an acrylic resin as a base and a plasticizer to keep the the paint from becoming too brittle. Acrylic lacquers were used extensively by General Motors in the 50s and 60s. Acrylic enamel came next, it is modified with acrylic resin and is insoluble in solvent when cured, unlike lacquers. In roughly the mid 70s., polyurethanes emerged. Their durability over the enamels and lacquers (they are much more "flexible") made them desirable. The technologies were further refined in the development of acrylic urethane single stages, and base / clear finishes which are the most durable paints available today. Modern paint additives for curing and hardening further improve the paint's performance.
How much will the paint cost? Material budget for single stage should amount to $250 - $400, depending on color and size of the car. Now this includes primers, reducers, paint catalysts (if needed) and materials like paper, tape, sand paper, sanding/grinding discs and filler. Yes, you will use filler, no matter how perfect your car is. Add an additional $75-$100 or so for clear coat. Always read the label directions for mixing, application, and safety. Better yet, get your hands on the manufacturers handbook for the paint line. Most all decent paint manufacturers have a book that specifies the mix volumes, "pot" life, drying time, etc. for each product (paints, primers and undercoatings) in the line. Many traditional paints such as acrylic enamels and lacquers are still available, but most agree that urethanes are the superior paints today. They are relatively easy to shoot and are very durable. They are also more expensive and typically have more dangerous vapors.
How much paint will you need? I used a single quart of unreduced paint for my '85 Cabrio. That quart alone was about $80. Now keep in mind a few things that affect, either positively or negatively, the paint usage. One, my car was a convertible (no painted roof), two, I used a gravity feed HVLP gun, three I had literally no practical experience painting cars and four, I really only sprayed one heavy color coat. You may also find, depending on where you buy your paint, that you may be forced to buy much more stuff than you need. For example my supplier could only supply primer in a gallon can, and the filler as well. Some suppliers can mix paint in any quantity you want however, my friend Tom mixes paint right at his shop, but then again he usually only mixes smaller quantities for collision repair jobs. And remember that there is no way to fix a paint job that does not have adequate coverage except for repainting the entire car. That said, I still dropped $400 for paint and materials for my small 'vert, but I have a bunch of primer and a bunch of filler leftover.
Another lesson learned, do not store your
paints and supplies in garages that drop below freezing. Some paints
will be unusable after they have been frozen.
The simple rule is the more you can take off the better. Many times it is far easier to remove something than to try to mask it off correctly. Bumpers, lights, door handles, body moldings, antennas, grilles and mirrors. If you are at all familiar with how you car is put together, this should be relatively easy. Removing windows is preferred, but not necessary. Allow at least a full 1/2 day for this. Take your time and mark anything that could be confusing to put back on.
The real mark of a cheesy paint job is overspray on moldings or mask marks on something that could have been removed with a single screw.
Here's a pic of my '85 cabrio just as I was starting the "weekend paint" job. Note that the moldings have been removed and you can see a couple areas where rust in the early stages was being addressed. The forward part of the front wheel arch had some perforation and there was a big old crease dent in the extreme end of the rear quarter, upper, that I had my body shop owner friend pull out with the Eagle.
But back to the windows for a minute, here's a great trick for painting around them: fixed windows like the front and rears, usually have a seal with an extended lip that sticks out over the body a bit. Sure you could mask that off real precisely at the rubbers edge, but you will still see a masking line there when it is all said and done. A common trick shops use involves using a 1/8" -3/6" (3mm-4mm) diameter cord, like a nylon sheathed close line. Pull the rubber lip back and go along shoving the cord under the lip with a popsicle stick, all the way around. Cut the cord at the end so the ends just touch under the seal. Shove it under the seal just enough so that when you let go of the lip, its outermost edge is being held up off the surface of the body by about the diameter of the cord. If you shove the cord back in too far, and the lip will roll over and down "swallowing" the cord. You don't want that. Now mask off the rubber seal, rolling the tape just around and under the suspended lip edge a tiny bit. You should be able to see the cord all the way around.
Now when you spray, the body surface normally
covered by the lip will be exposed a bit, allowing paint to "mist" up under
there, well beyond where the edge of the rubber lip normally lies.
When the paint is dry and the tape and cord is removed, the lip will lay
over newly painted surface and your car won't have that "amateur" paint
job look to it. (Sorry I don't have a picture of this technique...
I'll try to get one later)
Ok, this is only distantly related to paint, but worth mentioning. Stripping is about removing existing paint and coatings from your car before you paint. Remember, no matter what kind of paint you shoot on an already painted car, it will only be as good as the paint products under it. My rule of thumb is that unless the car is covered in known original paint, in pretty good shape, I would strip it to bare metal. You really don't want to waste your money and hard work on a $300 Earl Sheib paint job underneath it all, do you?
There are 3 basic ways to strip paint:
For any large area stripping, and for many other things, I am a huge fan of abrasive blasting. More on that below.
There are many good mechanical stripping tools/products, but what every professional body shop I have seen uses to strip paint is the good old "DA" sander and 80 grit paper. If you have a good air supply and a good DA (and 8" one will do a lot of work very fast) this is the way to go. Still not as fast as abrasive blasting and hard, if not impossible to get into tight corners and irregular areas however.
I have only used chemical strippers once, it was enough to convince me that I didn't want to use them again. A huge environmental, messy disaster. It is all too easy to get liquids down into areas that you cannot see, rinse, reach or paint, and then after the paint is shot, you see the effects of that. I know there are many folks who swear by them, and no doubt some who can use them effectively. But I'm not one of them, we'll leave it at that.
Abrasive stripping is by far the fastest and most effective way to remove old coatings. Now you may have heard that abrasive blasting heats and warps metal, and that you will "find" sand in your car for years to come. Well, in my experience, neither has been true. Taking your work to a competent shop will insure this. I had my '57 Beetle media blasted, inside and out, top and bottom. The shop ("Prep Rite" in Tewksbury, MA) uses a fine aluminum oxide media, blasts it at 25 psi and 300cfm (yes, no typo, 300 cubic feet per minute). There is no heat build up and no warping. About 20 minutes with my own shop vac and crevice tool on it with my '57, and it was the last I saw of the blasting abrasive in that car. A good shop knows how to plug orifices with tape to keep from filling them.
Can you sandblast yourself? Sure you can. All you need is about a 30 cfm air compressor and blasting gun. You need a huge, expensive compressor. If you have that and are willing to invest in a blasting gun, it may be for you. If you are like me with a 3.5 hp compressor, your uses for sandblasting will only be stripping small parts or small panel areas. I have one of those "blast out of a bucket" rigs that you can get at Sears for about $20. They actually work very well. That is if you can get the proper abrasive. I am fortunate in that a hardware store near me sells "Black Beauty" (silicon carbide, black sand) in 100 lb bags for $9 a pop. In 3 grits. In some areas the stuff is very hard to get. JC Whitney and Eastwood sell it, 50lbs for $80 (plus shipping). I have used my blaster for rust bubbles on panels, the inside of the ashtray on my '57 oval, a metal brake fluid reservoir, and stuff like that. Anything larger I farm out to my shop.
I paid the sandblasting shop about $650 for the work on my '57. Now that was the entire body, inside and out, top and bottom, except the areas inside covered by carpet and headliner. Dash, fenders and lids, both sides; doors, all but the inner cavity; plus a spare gas tank and a spare decklid. Money well spent in my book. See page 9 the '57 Resto Anthology for pictures.
There are other blasting abrasives out there that some shops use. Soda blasting is very popular, it is a very fine powder that pits the metal very little. But I have heard that some sodas are technically salts, that can get embedded in the metal and cause rust under the paint later. One shop in Rhode Island, I heard through the grapevine, went out of business after millions of dollars of damage lawsuits came their way. I doubt that is true of all soda blasting, but do your homework.
Crushed walnut shells are also used as abrasive blasting media. Mostly they are used for engine and machinery stripping though, where errant, left-behind particles will break down and not harm machined metal surfaces. They are expensive and there is no reason to use them for car body panels.
overall, whole car stripping aside, sometimes you just have to strip one
small area to address rust (especially if you are going to spray over original
"factory" paint). Here's another pic of my '85 cabrio, detailing
close up of a patched perforated area. For this I used only my angle
air grinder with a grinding disc. This newly patched area is
roughly ground down. It will be sprayed with etching primer sealer
(as will the entire car), but will not need to be "finished" as the wheel
arch molding covers up this area. The back side was wire brushed
and covered with undercoating. If you look close, you can see another
area that was patched at the extreme lower front end of the arch.
"How big of a compressor do I need to paint a car?" This is a common question. Well it all depends on the paint gun you will use, and possibly any air tools that you may use to prep the car. Compressor outputs are rated in cubic feet per minute (CFM) at a given pressure in pounds per square inch (PSI). Air powered device air requirements are usually spec'ed the same way, in CFM at a given PSI. Most spray guns of any kind operate in the 10-50PSI range. Compressor outputs are almost always specified at 40, 90 and for bigger units, 175 PSI. You want to insure that the rated output of the compressor you use is at, or preferably above, the air volume requirement of the gun.
Well how big of a compressor? How many horsepower? How big of a tank?
Well, to understand the relative function and effect of the compressor components, think of a compressor as a water pump and a big barrel. The horsepower spec determines how much water the the pump can move, let's say in gallons per minute (analogous to CFM). The barrel determines how much water the thing can "store up". Now lets say your pump is rated at 10 gallons per minute, and you have a 100 gallon tank. It will take your pump 10 minutes to fill the barrel (this calculation has little relevance to the compressor example, as the water isn't actually being compressed and the pump output rate isn't affected by the amount of water in the barrel). The pump shuts off when the barrel is full. Now lets say that you have a "tool" that uses 5 gallons per minute, and you attach it to a spigot on the bottom of the barrel. Once you start using it, the water level in the barrel falls and the pump starts again. But since the water going into the barrel is going in at 10 gal/min, and the water going out (what your tool is using) is at 5 gal/min, the pump easily refills the barrel and shuts off when it is full.
If your tool uses exactly 10 gal/min, the pump will kick in when the water level falls, but since the input and output are equal, the pump will run continuously while the tool is being used and the water level will not fall.
But if a tool is connected that uses 20 gal/min, the water level will fall, the pump will kick in, but since the tool is using water from the barrel twice as fast as the pump can return it, the water level will fall in spite of the pump running continuously, and eventually the tool will run out of water to use. But you can actually use the high demand tool for a short period of time, and/or intermittently.
That is an over simplified example, but it helps explain the principle of the compressor and the relationship between pump output (usually directly related to horsepower). Compressor put output actually falls off as the pressure in the tank builds.
What you need to keep in mind though, is that a spray gun is a continuous use type tool. Like a sand blaster and a "DA" sander, it uses a steady stream of air. Many tools are intermittent use tools, like framing nailers, impact wrenches and air hammers. What this means is that a compressor with a sufficiently large tank, can easily operate a tool that requires more air (CFM) than the pump can supply, if the tool is used only intermittently. But for continuous use tools, an adequate CFM rating is required, and a large tank really can't make up for any shortcomings there.
So what size compressor are we talking about? Well, let's look beyond spray painting, as a compressor is a tool that will be used for many other things and is a good investment (tell your wife that). Most "do it yourselfer" type intermittent use air tools like impact wrenches and air chisels will use around 4 CFM at 90psi. A 4 CFM compressor may be as small as 1.5 hp. But you wouldn't want to buy a compressor with the bare minimum you expect to need. My recommendation is that a minimum sized compressor for home use should be 6-7CFM at 90 psi. This would be a 3-5 hp unit.
Now paint sprayers require a wide range of CFM, depending on type. It used to be that HVLP (high volume, low pressure) paint guns needed massive amounts of air, like 15-20 CFM, but only at 10-30 psi. Note that the CFM/PSI curve of any compressor is not linear, but you can extrapolate the values out a bit. If the compressor you are eying is rated at 6CFM at 90 psi, and 8.5CFM at 40 psi you can make a graph to estimate what it might deliver at 20 psi for example.
So in this graph, it should be clear that the compressor would probably deliver 9 CFM at 10psi for example, or about 7 CFM at 50psi. The curved blue line is, at least in profile, more like the actual CFM/PSI response curve of a compressor.
A 3-5hp compressor with a 25-35 gallon tank is a good homeowner unit, and can be purchased new for around $350. In my opinion (and order of preference), Ingersoll-Rand, Cambell Hausefield and Sears are good brands. One mail order tool outfit who sells a good selection of compressors and will ship them for free (yes, free), is Harbor Freight Tools.
If you will be using more air, possibly with
larger scale sandblasters or more demanding spray guns, the next step up
in compressors is usually to a 2 stage and possibly 240 volt unit.
Yes, you can get single stage units on big "fat boy" tanks up to 6-7hp,
but the realized increase in CFM is seldom worth the added cost over the
$350 units. Once you get to the 2 stage units (most all of them 240
volts), you see a huge increase in CFM (11CFM at 90psi and up), an increase
in max psi (up to 175) and of course, an increase in price (usually start
at around $800).
Air quality is very important to a quality paint job, and your two enemies are water and oil. Oil may be in your air lines if you use an in-line oiler and air tools. I use an oiler at my regulator station. For this reason, my hoses invariably have oil residues in them. So I have a "paint only" air hose that I use for spraying, and connect it only to an air tap after the regulator and before the oiler.
A good way to get water out of your lines, especially if you live in a humid climate, is to make sure the compressor tank is de-pressurized, open to air and dried out before you use it. A couple days before you paint your car, open the tank drain valve on your compressor and leave it open. If possible, open the pump outlet too (you can insert a blow gun and rubber band the trigger). Don't pressurize the tank until an hour or so before you expect to spray.
And another neat trick, I learned from Thom
Fitzpatrick; if you have an extra long spray hose, coil it up in a
big washtub, and fill the tube with ice and water. This will act
as an "intercooler" for the lines and will wring moisture out of the air
before it reaches the gun.
Inexpensive spray guns that will do a decent job are available for around $50. Professional guns cost around $500. I have used a couple "old fashioned" suction feed gun as well as a gravity feed HVLP gun. I also have a small suction feed "touch up" gun. I find the HVLP gun to be much easier to use and more predictable. Harbor Freight sells a DeVilbiss "clone" HVLP gravity feed gun for around $50, I have one and used it to paint my Cabriolet. Their product number is 43430. The air consumption of the gun did tax my 3.5 hp compressor a bit, but I could easily pause for a minute or so and let the compressor "catch up" when I needed to. The air consumption spec on this gun is 9.5-14.8 CFM at 15-50 psi. I think I ran the gun at about 40 psi and my compressor is rated at 8.5 CFM there. The gun has a small regulator and gauge at it's base which is very useful.
My HVLP gun is shown in the pic on the left (click on it ot see a bigger image). The little white ball looking thing at the very bottom is a "last chance" filter and water trap.
Using the spray gun and cleaning it properly,
are challenges unto themselves.
How They Work
Most all spray guns have two stage triggers. When you pull the trigger a little bit at first, air flows from the tip, but no paint flows. Pull the trigger farther, and paint begins to flow. You can "feel" the added load of the second stage when you pull the trigger. All the guns I have used have had adjustable paint flow "pins" on them (the pointed steel rod that obstructs the paint tip when the trigger is released). Opening up the paint flow tip means that more paint flows out when the trigger is pulled back all the way. Other adjustments commonly found on guns are airflow adjusters (the regulator at the bottom of the handle in the case of my HVLP gun) and and pattern adjustments. The pattern adjustments adjust the air "fan" pattern that directs the paint. On my HVLP gun, I can adjust from a spot, to a tall oval "eye" shape. I can rotate the orientation of the eye shape by loosening the collar on the tip and rotating the fan head. It may be hard to visualize these features if you haven't ever played around with a paint gun, but when you get your hands on when, they will make sense.
Yes, you must have a mask, and more than those "nuisance dust" kind. Auto paints contain solvents and compounds that will seriously affect your health, even if you just breath the fumes once. But you can get a good mask for cheap. The stuff you should be particularly cautious of are two part paints containing isocyanates and hexamethylene diisocynates. The catalysts used in these paints 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. Make sure the mask you use states that it is intended for these paints, if you are not sure, ask at the place where you bought it.
I bought a disposable 3M mask at my local autobody store. It was charcoal activated and was good for 30 hours of "out of the bag" use. It comes in a resealable ziploc type bag, and is effective as long as it is not out of the bag for more than 30 hours. It cost about $18. It has a large rubber mouth/nosepiece fit very well and was very comfortable. With the proper mask, you should be able to smell nothing. I can wave a dripping, thinner soaked rag in front of my face with my mask on and smell nothing. I think I figured I used only about 5 hours total of mask time when painting my car.
A fresh air mask is a ventilation system that usually has a full hood and a pump, placed outside the painting area, that pumps fresh air to the user. These are the safest systems, but can be quite expensive.
There is some discussion as well as some disagreement among painting professionals
about whether these kinds of masks are acceptable for use with paints containing
isocyanates. I will tell you that I called 3M and asked them about
this specific mask and the guy said that it was appropriate for use with
isocyanate paints (virtually all urethane paints contain isocyanates),
but to be honest, he didn't give me a great deal of confidence that he
knew what he was talking about. You make your own decision.
As I paint very infrequently, I have made the decision for myself that
this mask is OK based on the information that I have. For more info
in isocyanates, see this
website from NIOSH on "Preventing Asthma and Death from Diisocyanate
Exposure", and as always, remember that you are responsible for your own
Sanding is probably 50-70% of the prepwork for painting a car, and after you do it, it will seem like it was more like 98%. Sanding is the resurfacing of body panels, making them progressively smoother by rubbing an abrasive sheet on them and removing material..
Here's some more pics of the '85 Cabrio.
Masking is the application of tape and paper and other blocking materials over areas that you don't want to get painted; and it is a science unto itself.
Rule #1: Always use fresh masking tape. Perhaps you didn't realize that masking tape was "freshness dated", but it is. No, it doesn't have a "best if used by:" date stamped on it, but it does get old. Old masking tape may seem OK, but it is less flexible, hard to get off the roll in a length without it tearing, and perhaps most importantly, the adhesive has dried out a bit, it will be harder to remove and it may leave adhesive residue behind. You don't need this headache, buy a couple fresh rolls of tape. And yes, you can get "ordinary" masking tape at Home Depot, it will work just fine. 1" and 2" wide rolls seems to be good choices. You will use a lot of it.
What is special about the paper? Well for one it is cheap and roll goes a long way. I bought two rolls for a bit over $5 ea., and in spite of having to cover a whole convertible top, still only used one roll doing my Cabriolet. This paper is heavier than newspaper, and has a light wax coating. This keeps it from absorbing water that might splash on it when you do any final wet sanding after masking.
I mention this masking station in detail because I absolutely cannot fathom painting a car now without one, that is trying to tear, cut and fit newspaper by hand instead. It would have taken me ten times as long to do the masking. In spite of the headaches getting it all working, it was well worth it. So you can learn another few things here and maybe get through it a bit faster than I did:
Hopefully it goes without saying that you want as clean an environment as possible to spray in. Personal safety considerations aside (like mask, gloves, goggles, etc.), you should have three main objectives:
So let's look at your situation. Can you paint outside? Of course you can. But what control do you have over the elements listed above? Ventilation should be no problem, but other than that, you might have some real problems (Note: A freshly painted, bright yellow car attracts gnats in droves. Ask me how I know). Painting outside is seldom ideal over any indoor options, but, if you truly had to paint outdoors...
You would want to have a surface for the car that is virtually dust free, pinning a large plastic tarp down would be a good idea. You would want a warm day, preferably 70-80F, and virtually no wind. That, I think would optimize outdoor painting......
The "garage" spray booth
Creating a decent spray environment in the garage you normally park cars in and work in is a challenge, but it can be done. Rule number one is that dust is your enemy. Any kind of light, small particle. Remember, you will be spending a few days just shooting streams of air all over the place. So job number one is to start by eradicating as much of it as you can. Get out your shop vac and start in the higher areas first. Shelves, hanging light fixtures, work surfaces, kneewalls. Look for the areas that are least used. When you are done, give the floor the weeping of a lifetime. If possible, spray it out with the hose. But keep in mind that if you are going to spend a few days sanding primer and filler in here, you are going to be creating a lot more dust, so you will just have to do this all over again if you aren't ready for spraying. Best to do the "big clean" right before you spray.
I have heard of folks draping the garage walls with plastic sheets and tarps, but I took one look at my garage and came to the quick conclusion that it would far easier to just give it a good clean.
Make ample space to work in. Consider
moving stuff out of the garage you might not have ordinarily thought to
(you might be removing some dust in doing that!). You will ideally
need about 4-5 feet of space on all sides of the car to get you, a spray
gun and an optimal distance from the gun to the car in. I have seen
pics of people spraying cars in garages with barely enough room to walk
between the car and wall, but I'm sure the results suffered somewhat.
Make all the room you can. If you can't move it outside, but have
some floor space to work with, move it all in a pile and cover it with
a plastic tarp.
Ok, we've covered taking stuff off, sanding, masking, setting up the gun. Let me mention some final preparation details that I haven't already.
First examine every single square centimeter of every panel you will paint. I can't tell you how easy it is to miss a filler edge, or ding dent, or coarse paper sanding mark. Examine everything, slide a bare hand over it slowly. Now go get another light source, like a drop light, or even a table lamp without a shade. Plug it in and walk around the car with it. Lighting can hide imperfections, no matter how good the light in your shop is. Carrying another light source around with you when you do final inspection can really uncover areas that you might have missed. Move the light source back and forth. Now, put the light down, and go in the house. Have a cup of coffee, a Coke, dinner, watch TV, do something else for a while and "turn off" your painting thoughts. Then after and hour or two, go out and inspect again. The mind has a way of masking out things we ordinarily would know are wrong if we just stare at them continuously (ask me how many times I have proofread stuff I write half a dozen times, only to upload it to the web, read it an hour later and see all kinds of errors!!).
If you stopped short of a panel edge in doing your fine finish work because some body molding or trim "will cover that up", go get that body molding and hold it up there, and make sure it actually will. I have more than once neglected to finish and area because it will be a "not seen" only to find after the paint dries that it is!
Go over your masking work again. Look for loose tape, open pockets or holes, missed areas. Again, imagine that you are a high velocity, airborne paint droplet. You can go anywhere! Make sure that all edges of masking paper are taped down, and that there are no flaps or pockets. Why? Because you will spraying air, and air can easily catch a flap and flip it back over fresh paint. And, flaps or pockets can catch air and trap dust particles that might get blasted out later. Tape every edge down! Remember, pockets and cavities in the paper is bad.
Mask off the wheels, then tape "skirts" along the lower edges to the floor, leaving a good 6" of paper laying on the floor. You don't want air from the gun to pass under the car because it can catch and blow up dust particles and crud that is under the car. This is one of the finer details of masking. See the pictures of my Cabriolet all ready for spraying.
Now, if you have a garden sprayer (pressure bottle), go full it with fresh clean water, and adjust the nozzle to produce a fine mist. Then wet the floor all around the car, including the paper skirts. "Stick" them to the floor with water. Why? Airborne particles that get down to the floor will get stuck in the water and won't get in your paint. This works especially well in a down draft booth. If you don't have a bug sprayer, a hose with a sprayer nozzle carefully feathered for a fine mist will work. Do this before the final wipe down of your car.
Just before you are ready to spray, get a clean, lint free, dry cloth and wipe down your whole car. Shake out the cloth real good, then do it all over again. Then, put the air gun on the air hoes, dial up about 40 lbs of air, and blast off the whole car. Do this while the floor is wet! Do not use more pressure or get the blow gun too close to masked off paper. You might tear holes or pull the tape loose.
Did you read the compressor stuff above?
Don't forget to depressurize and drain your compressor's tank a couple
hours before you spray and then pump it back up again. This will
reduce the amount of potential moisture in the lines.
You want to know how dust free your environment is now? Turn off the lights in the garage and flip on a nice bright flashlight, point it straight up, hold it in front of your eyes about a foot away and look into the beam. See any particles floating around? I'm sure you will see some. If you just blew off your car with the air hose and you now see hundreds and thousands of particles in the air, you will get hundreds and thousands of particles in your paint as well. As a benchmark, try this outside, at night, in the yard. You'll be amazed at what you see...
Lastly, before you spray, you want to have your work space as well lit as possible. Get every light you can plug in (and have it still out of the way) and turn it on. Bounce some lights off the ceiling if it is a bright color. A mix of flourescents and incandescents works well. You simple can't have enough light.
Now we already covered some basic spray gun stuff, but where do you start once the paint is loaded? Well, this requires a little thought and a little planning. Fully painting a car is a multi step process and the first spray step is called jambing. No, this isn't turning up the radio real loud when the Black Crows comes on, jambing comes from the term "door jamb" and refers to the painting of those "in between" areas. Open you car door, see the areas that the door closes against? Top, bottom and sides? Open the trunk and hood, see any more? What about the whole trunk area? Didn't think too much about those areas did you? Yes, you could paint just the "outside" of your car, but especially if you are changing colors, when you open the door it will look like crap. Engine bay perhaps?
Jambing is a pre-paint step that requires
some thought an planning, and it can take quite a bit of time. It
will require you to temporarily mask off some areas and sometimes must
be done a day before the final painting of the car. The idea is to
do all the "lesser seen" areas ahead of time, so when it comes to that
final exterior paint, you can close all the doors and lids and just spray
Jambing brings up another not so obvious dilemma, one I call "transition zone perils". That is, how can I spray one part of a panel one day, then another part of that panel the next and not make it look like a 2 step paint. For example, how do you spray the A-pillar area of the door opening one day, and then the next the front quarter panel that meets that A-pillar area without having that transition area look like crap? Well, there are several techniques to this that body shops use, and they can be employed all over the car actually. And just straight masking the areas off usually isn't the best option.
The first option, and usually the best, is to hide that transition area under something. For example, if you were jambing an empty engine bay on a Beetle body (or just painting the upper rear apron), you would want your transition area to be just under the decklid seal, there is an area about 3/4" wide to play with there. Same for the trunk area of a Beetle body. You could mask if you wanted as no one would ever see that there is a hard mask line there when the car is all done.
Another method is to make the transition zone on a hard panel curve or rolled edge. An example of this would be the A-pillar on a Beetle. Make your transition area the outer "sharp" edge of the drip rail that follows the roof of the car all the way down to the lower quarter. That is, jamb paint to the door opening side of the drip edge (might have to have the door off to do this right), then exterior paint the outside. The transition area would be right along the outer edge of the drip rail. On a more conventional car (like my Cabrio), the transition edge of the B-pillar (door post where the door latch is) was just the where the B-pillar rolled over a 90 degree bend and became the outside rear quarter. Not a real hard edge, but enough that unless you look close, you couldn't tell the paint was "transitioned" there.
Other good transition places are body panel seams, or, outside the car, under body trim and moldings.
To address the transition area, the best way is to paint panel "A" (say the door jamb/opening) trying to minimize the overspray onto panel "B" (say the exterior rear quarter panel). Let the paint dry, then re-sand and prep the oversprayed area on panel "B". Then spray panel "B" trying to minimize the overspray onto panel "A".
With base/clear (2 stage) paint systems, a method that works well is to base coat the two panels in two separate steps, then wet sand the transition area, then spray it all with the clear. You can sometimes get better transition area "matching" with clears than you can base coats.
One last thing to mention is "soft masking". Let's say you want to paint to line where you will be transitioning. Get a piece of paper, masked one one edge, and lay the taped edge to the right or left of you line by about 2-3 inches, with the paper covering the line (I know, this is the opposite of what you are thinking). Now take the un-taped edge, and roll it back over the taped edge and tape it down to the paper. This creates a rolled paper "edge" just over your line. The idea is that this creates a "soft" barrier for the paint. Some will mist under the roll and when you remove the paper, you won't have a "hard" masking line to deal with.
But back to jambing. Come up with a
plan to address all of these odd areas. Door jambs, engine bays,
trunk cavities. yes you can leave them the original color.
If you are painting the car the same or a very close color, maybe that
isn't that bad. But painting a red car blue, you might want to think
about this a bit.
OK, let's summarize the steps here.
Well, like any project, there are some lessons learned, let me tell you mine.
1. Trying to paint a car in along weekend was not a good idea. I had given myself 3 days, ended up taking another day off work, spent 12+ hours each of the 4 days, and barely had a driveable car in the end. Don't rush this. My car required a little metal/body work, but was for from a basket case. Nonetheless, I'd estimate about 100 man/hours to do this right as a minimum, especially if you are unfamiliar with it.Those were the basic mistakes I made. But overall, I was pretty pleased with the way the car came out. Not a show car, but it looks nice, and it was don "the right way". And I learned a lot doing it. I can expect this paint job to last a while (although as I type this, the '85 is for sale, I bought another Cabrio, a '91). Take your time! taking parts off, masking, sanding, spraying. You CAN do this yourself!!
Here is a link to a great list of autobody terms from autobodystore.com. Another one here, from Canada's "Cascade Collision services" website.
Copyright© 2001; John S. Henry