How to Repair Clearcoat
Kevin Tetz Shows the Best Way To Fix Paint
Since the 1980s the automotive manufacturers have been painting cars with two stage, base coat/clear coat systems. That may not seem all that long ago to some of us older guys, but these cars are now 30 years old and entering prime project car territory. Because drivetrain technology had hit its stride by then, cars like 5.0 Mustangs are still running and driving just fine. But many cars from the 80s and 90s have clear coat paint that is just peeling and flaking off in chunks. Some cars, like the Plymouth Neon, seemed to have paint and clear coat failing before they were even off lease.
The bad news is, you can’t just sand for adhesion and respray clear coat. Modern urethane paints are thermoset paints, once they “dry” they won’t flow again. The clear coat creates a strong chemical bond with the still slightly “wet” paint and locks in. You can sand for adhesion and spray a new coat of clear over the base, but it will never lock in, and it will always sit on top of the old clear at the edges. It will never be as strong as the original, and will fail much quicker. (I put wet and dry in quotes because urethanes cure by a chemical process, not by the evaporation of a solvent the way other paints dry).
The only option for a proper, permanent repair is to sand the whole car and respray color and clear.
How To Do It Anyway
That being said, it is still possible to do spot repairs to clear coat in certain situations. It is important to realize though, that they should never be considered permanent repairs, long-term repairs.
This hood is typical of most cars with delaminating clear coat issues. And people ask all the time, why can’t I just put clear coat back on? The problem is, once the base coat has been exposed to the sun and air it is compromised. The color coat is only to provide color, it is not stabilized for UV or exposure to air and contamination, and once it has been it is only a matter of time before it fails too. Putting clear over the top of it will delay that, but it will still continue to deteriorate under the new clear. Plus the adhesion is gone, and sanding it to get it back makes it almost impossible to match and blend it to the surrounding areas.
Now Jaded, the pro-touring SEMA show Mustang has some minor flaws in the clear coat mostly brought on by the frantic pace at which Kevin had to finish the car for the show. One of them is a perfect example of the type of clear coat issue you can fix. There are several reason this can be fixed including: 1) The base coat has had little exposure to the elements 2) It’s in an easily blended area 3) It’s small and out of the way so not likely to be seen.
Jaded was shot with all Eastwood products originally, including the 2K European Urethane Clear Coat. The Eastwood 2K Aero Spray clear coat in an aerosol can is so good; you can use it to repair the finish of even this show car. It is a professional quality coating in a rattle can.
Now the 2K Aero-Spray is a real activated 2K paint, and that means it contains isocyanates. So if you are doing any significant spraying with it you ought to be wearing an activated charcoal facemask to protect your lungs.
Clear Coat Edge Repair
1) First clean the area to be repaired of organic contamination. A glass cleaner with alcohol works well for this.
2) Next clean it of any inorganic materials with a solvent based cleaner like PRE paint prep and a clean rag.
3) Next, use a fine grit grey non-woven pad to scuff the paint in the area of the repair, and about 1 inch to either side of it. Then wipe it off again with more PRE paint prep.
4) Mask around the area to be prepared. Since the paint the masking is going over is suspect, it’s a good idea to whet the tape, by running it over something like your pant leg to remove a lot of the stickiness. Kevin is using a technique called back masking, in which you stick the center of the tap to what will be the edge of your repair area, then fold it back. This gives you a softer line, and lets you fine tune exactly what is going to be masked without having to peel and stick several times.
5) Pop the button on the bottom of the 2K spray can and shake well. The aerosol flows and covers well, so there is no need to try to put a thick coat on. Spray your first coat, and then leave it to flash.
6) After about 5 minutes the 2K should be dry to the touch and not tacky. Do a touch test and if it passes, it’s time for the second coat.
7) Spray a second quick light coat, same as the first, and the paint is done
8) As you unmask, pull the tape slowly and carefully away from the just painted area. As you can see, the repaired area stands out from the original clear, but the flaking and delaminating is gone. Now it’s just a matter of hitting it with some 2000 grit sand paper, then polishing compound and a buffer to blend the edges into the older paint.
Blending Repaired Clear into Old Clear Coat
Now that Kevin has showed you how to clean, scuff and spray a small repair area, let’s move over to a larger panel and show how you blend new clear in with older paint.
This Ford Ranger fender had clear coat that was in as bad of shape in spots as the blue hood. We cleaned it and scuffed it the same as the edge repair on Jaded, and sprayed it with 2K Aero-Spray. Here you can see the glossy area where we repainted it, and the hazy area we will end up blending into the original clear paint.
As we said before, this is not the correct way to do things. The area where you are blending your new clear into the old clear is going to end up thin, and weak. The way a legitimate body shop would do it is to at least paint the entire panel, all the way to the edges. That way there is no blending needed, and no spot for potential failure that is going to come back and bite you in a year’s time.
Much like the smaller repair on Jaded, this fender was sanded for adhesion before painting. The area that needed the repair was hit with 1000 grit sandpaper, as was an additional area about 2/3 that size where the original clear coat was still good. That area is where you will accomplish the blending.
Here is how you blend the repair:
1) Clean the area again with a clean rag and glass cleaner, so you avoid grinding dirt into the paint as you try to blend. Take some 2000 grit sandpaper and wet sand the transition between the new clear and the old. Don’t be too aggressive, you just want to knock the roughness of the overspray down.
2) Now, apply a little bit of rubbing compound and work the area with a buffer. You’ll want a variable speed buffer on the lowest setting, something like 600rpm. And you want to use just the edge of the wheel where it moves away from the area you just painted, and toward the old clear.
3) And that’s all there is too it. Buff until you can’t see the transition from new repair to old paint, but use low speed and light pressure because you only have a very narrow window between looking great and failure. If you buff it too much you have no other option, but to paint another coat of clear again. Here you can see the difference between the area Kevin points too, and the area above it that has been buffed and blended.
Question and Answer Time
How do you spot repair if you need to lay down some color coat too? – If you have to spot in some color when doing a clear coat repair, like on the blue hood we looked at earlier, you do it just the same way. The only thing you need to be careful with is where your transition line is. You want the new clear coat to extend way beyond the new color so you have plenty of clear to buff out without peeling back the new color paint. On the fender the 2 solid lines represent coats of base coat I would spray, then the 2 dotted lines are a blend coat and a drop pressure coat of color. The wavy line represents where the new clear coat should extend too, so you have plenty of room to blend.
How long do you have to wait to cut and rub out clear coat? – That really depends on the paint you are spraying. Some can be rubbed in as little as 12 hours. But since catalyzed paint continues to dry and shrink for 90 days after application, buffing it that soon can lead to it not looking right after it has dried for a few more days. For a show car, or anything that is not in a high turnover collision repair shop that needs to get them painted and out the door, its best to wait at least a week afterwards. Now there are some clear coats, like those used in the factory, that are dried enough to start buffing in as little as 2 hours. Typically the paint will have this information on its P sheet, but the minimum for quality work is usually 24-48 hours.
Should you use a rotary buffer or an orbital buffer? – It really comes down to person preference. Kevin prefers a rotary buffer for initial buffing and smoothing of paint because it has a more aggressive cut. Afterwards he switches to an orbital buffer to polish it and take out the swirl marks.
If you are shooting a single stage urethane paint job, can you put clear over top of it? – Yes, you can. You need to make sure to paint it in the correct window to get good chemical crosslink adhesion, which is also on the P sheet, but it’s usually something like 12 hours. But if you are just going to shoot a base and clear over top of it, just use proper 2 stage paint. IF the color isn’t available in 2 stage, you aren’t going to hurt anything by clearing over single stage.
Here’s a good trick for super deep looking single stage paint using clear coat paint over it. Spray your single stage color coat and get a nice solid coverage. Then mix 50% color and 50% compatible clear together (after activating each of them separately) and spray another coat. On top of that add a coat of 25% color and 75% clear, and top it off with a pure clear coat. What this does is makes the light refract as it penetrates the clear/color coats and softens it, so when it is reflected back you get a stellar, super deep, glossy paint job. This method also gives you a coat of pure clear paint to buff and rub without having to worry about affecting the color at all.
On a full restoration, do you cut and rub before you put the glass and trim back on the car? – Absolutely yes. When the car was originally assembled at the factory the body was sent down the line and primed and painted before the interior, glass or trim was installed. You can’t get a proper restoration if you are trying to rub and cut around the trim and emblems on the car. Take it all apart, spray the pant, let it sit for a week, cut and rub it out, then reinstall the windows, trim and emblems.