Wet Sanding & Clear Coat Failure

SR77 · 08-29-04, 01:11

Can Wet sanding and then compounding with a rotary be done without Clear Coat failure down the road. I have read alot about clear coat thinkness threads on here and the fact that you aren't suppose to remove any where from .3 to .5 mils or there will be clear coat failure in the future. I am going to try and restore the front end of my sisters car which has some touch up spots that need to be wet sanded down and the hood has some pretty bad water spot etching. I am asking because I am not sure if wet sanding and compounding once will remove to much clear coat, but also because she plans on keeping the car for a long time and I not only want to resore the shine on the front end without a clear coat failure down the road, but i also want to be able to clean and polish the paint to keep it maintained too in future details. So, can wetsanding and compounding be done without the risk of clear coat failure and will i still have enough clear coat left for future cleaning and polishing of swirl marks down the road? Also, What does Clear Coat failure that everyone talks about on here look like? thanks for the help.

jrawls · 08-29-04, 03:04

I wouldn't risk it especially if you're not very experienced with it. Wet sanding does remove a lot of clear coat because after you sand it you have to compound and polish it afterwards to smooth it out. If you do remove too much clear coat you may not notice right away but within a month or so it will start to fail.

SR77 · 09-06-04, 03:06

Anyone else? I hope it can be done without any future problems. I don't understand why they teach wet sanding at detailing seminars if it is bad to do on clear coats. Also, can anyone tell me what clear coat failure looks like. thanks

Matt M, PA · 09-06-04, 07:45

Clearcoat sanding and heavy compounding ARE NOT for the weak for heart. If you realize that the entire amount of paint on your car...including primer, color and clear...is something like 5 mils....you can see why it would be easy to cut through. (A good plastic trash bag is 2 mils.)

Clear coat failure can look a few different ways. Once way is that it will look like it has lots of cobweb looking like scratches. It also can peel off like old skin.

I would strongly recommended NOT wetsanding your car...if you rally want it done...take it to a good body shop. Also, if you are looking to sand out orange peel...forget it. You could take off more paint than is safe to do.

The failure will not happen overnight...it could take weeks or months.

wing · 09-07-04, 12:25

You could always get it re-cleared though, so if that is within your budget it might be worth doing.

I have a spot I'm fixing on my fender, I sanded a little outside my touch-up and got down to paint :scared but it's all good, a little touch-up and some clear and it's all perfect again

SR77 · 09-09-04, 05:19

thanks for the replys. If wet sanding is so dangerous, then how do you guys level your touchups?(Other then Lanka) I don't understand why the detailing seminars that are offered teach you to wet sand out defects and touch-ups if it is going to damage the paint or clear coat and lead to failure. I was at a local seminar recently from Meguiars and they showed us how to wetsand and then compound the paint to remove both defects and to level touch-ups. Why would they show us this if it can't be done safely with clear coat failure. I read alot on here about people wetsanding to level touch-ups and want to know how they can accomplish this future clear coat failure, and still have enough clear coat left for future polishes. thanks again

Bill D · 09-09-04, 05:26

The thing about wetsanding a touched up chip is that it is such a localized, small area that it almost,sorta "doesn't matter". Also, often times, we don't apply new clear to the new TU paint, making it sorta "safer" to do. I've gone over a few spots with wet sandpaper extremely lightly just enough to haze up the paint to make polishing more effective than it was before the wetsanding. I've also made mistakes wetstanding and dug too deep into the paint. I guess it's sorta like learning the rotary but practice and lots of it is even more critical.

Accumulator · 09-09-04, 05:33

SR77- Heh heh, I'm not gonna comment on why some people do the things they do

But it's smart to think for yourself and you're asking the right questions.

When you wetsand touchups, the idea is to do almost all of the abrading on the raised, "extra" paint from where you touched it up. I last did it with a 2,500 grit sanding block, and I didn't touch the surrounding paint much at all.

If it's a keeper, I wouldn't thin the clear/paint any more than necessary for any reason. I wouldn't try to remove the etching from the acid rain, for instance.

FWIW, most companies don't tell you how much clear their products take off. AutoInt says a bit more than most, and their "paint correction cream", a rotary-use compound, is something that you can't use more than a few times without causing clearcoat failure. And that's over the whole life of the car. I honestly wonder how the cars that have been "aggressively fixed" are gonna look a few years from now. For the most part, I'd rather have imperfect, but original paint.

One last thought- consider that your sister might have very different ideas that you/we do about what's acceptable. And if/when it gets marred again, you're back to the same dilemma, with even less clear to work with.

Jimmy Buffit · 09-09-04, 06:36

I say slow down.

Odds are that you do not have access to a paint thickness guage... how will you know when you've removed 'enough'?

Wetsanding is easy to do. Impossible to fix.

Slow Down.

Jim

SR77 · 09-10-04, 07:06

Thanks for the replys, especially Accumulator, thats the response i was looking for. I guess I will just leave the acid rain damage and just do the touch ups. Do you just wetsand the actual touchup only or do you also do the surrounding area to blend it in? If you do the surrounding area also how much do you do around the touch up? thanks again for the help

Bill D · 09-10-04, 07:39

SR77,

Yeah, do stay away from wetsanding the acid rain. My Dad had his car wetsanded for that reason a while back, the clear is probably the most fragile it can be. In fact, on one part of the rear deck I actually got some color on my pads. To me,not worth it to do.

I've always wetsanded the TU itself only. I'm betting you can put some painters tape around the surrounding area to not come in contact with it. I think David B's write up on wetsanding the TU describes more detail as well as other articles on the topic elsewhere online.

Hope it goes well!

Accumulator · 09-11-04, 09:50

Yeah, I too try to keep my abrasive work (wetsanding especially) confined to the touchup paint. The only "blending of abrasion" I do is when I hit the area with a mild RC to remove the sanding marks (which are hopefully only in the touchup paint). You probably *won't* be able to confine these efforts to the touchup paint, but if you try you'll do less to the surrounding, "good" paint. And the subsequent compounding/polishing will just be removing fine marring like any other swirls/scratches/etc.

The touchup might never be completely undetectable, but at least it's better than some big divot in the paint or a big blob of touchup paint. So know when to say "good enough"