Buffing clearcoat

[Burke Kilgour]

I just clearcoated my AE-21 on sunday and it turned out really well, with one hitch. The whole boat is perfect except for the bow center (the area I wanted PERFECT).
I laid down the clear pretty heavy in this area and ended up with some "solvent popping" in the finish. Small tiny, tiny bubbles on the surface, almost on top of the clearcoat.
I've heard of this and have never had it happen before.
I'd like some tips on polishing DuPont ChromaClear 8500s please.
I can see the clear is really thick in this area, and the bubbles are on the top, so I just have to polish it down a very small amount.
I've never tried this before and don't want to f*** it up.
I bought a 2 speed polisher, I just need the "tried and true" ideas for buffing pads, compounds, speeds and what NOT to do.
I'll try to take some digital pictures, but the bubbles are so small that I don't think they'll show up.

Thanks,
Burke

[vector mike]

I've removed "orange peal" before by wet sanding and then buffing afterwards. I'm sure this would get rid of the bubbles if they are not too deep.

[lorax]

I've used 2000 grit paper to nub sand defects like the ones your describing. The book I've used as a reference says that very fine grit paper is a much more controllable way to remove paint(clearcoat) than buffing.

Check out the link to this thread. http://forums.screamandfly.com/showthread.php?s=&threadid=15998

I'm no authority but the guy who responded to my post clearly is. Maybe you can drop him a line.

[Techno]

Go here and post your question. You could go through the archives but you mentioned solvent pop so it may be more than just a buff thing.
Depending on whether or not your clear is cured and how much orange peel, you need to use pretty rough paper. Not 2,000 but maybe 800. They'll spell it out though, good site.

http://www.autobodystore.com/cgi-bin/config.pl?index

BTW you have to sand & polish all of it for the extreme look. You don't have to but it will make a difference.

[Burke Kilgour]

Heres a pic of the bow, I'm gonna try "macro" with my digital camera to see if I can get the defect to show up.
Thanks for the links

Burke

[Burke Kilgour]

It doesn't show up in the last picture, but I caught it in the reflection of the light above it.
It's pretty clear here.
It only shows up on the black stripes on the bow, the black stripes everywhere else is OK.

[WILDMAN]

Burke, You WILL NOT get rid of the solvent pop by sanding and buffing. It will actually make it show up more. This is because you break the bubbles when you sand it, and then you have pits that hold the rubbing compound and make it show more. I've tried lots of times to repair this problem, and believe me, there's no easy way. You need to bridge the bubble gap with epoxy primer or clear, then sand flat and put a couple coats of color back down, then clear again. Solvent pop is caused by too much paint, too fast! When it's hot out, you need to wait long enough between coats. I started using a new clear from Dupont that dries fast and does'nt seem to solvent pop. I don't remember the number, but if you call me, I'll give it to you. 386-761-8050. See-ya WILDMAN

[Burke Kilgour]

Thanks Wildman, thats kinda what I DIDN'T want to hear, but thats the way it goes...............
The clear is directly over the gelcoat, so could I get away with sanding this area, re-clearing, and buffing the transition between the new and old ?


Burke

[Burke Kilgour]

Hey Wildman, I tried to give you a call at that number and it must be your work number.....................

Burke

[sho305]

I would start with around 1000grit, and sand it out. Work up to 1500 when they come out and go over it with 2000 to finish. Re-clear and have some fish eye and enamel reducer handy should the worst happen. Could have been contamination, but likely what you said.

IMHO, the wet sanding saves lots of energy buffing. I only sand the flat open areas, as the corners and high spots get buffed harder, and other little edges are not noticed. I like to slow the clear down for a nicer finish, particularly the last coat. That helps with the solvent thing too. I also let it tack up good when going 3-4 coats. Not daring to go more than that at once, I make the last two a double coat usually, so maybe 1.5 (2.5-3.5 total)coats really. I think they recommend 3 coats max? I put 10+ heavy coats on a wood console once, about one per week. It never cracked in the 3 years I had it.:)

[Burke Kilgour]

Thanks sho305, heres the scenario......
I put on 3 coats of clear with a 45 minute flash time before the last coat. Temps were mid 70's, medium reducer, mixed per the can directions with a little extra thinner on the last coat to help level it out for the "glass" look. I've done this many times before and never had this happen before. Maybe it just wasn't my day..............
Although one of the guys on the autobody forums mentioned that a person would be "taking chances" by putting more than 2 coats of hi-build clear on, for fear of "solvent popping"..........hmmmmmmmm.
As far as sanding to that extent, that may be a bit of overkill because this is "hi-build urethane clear". It fills in scratches that would be from about 20 grit paper!!!!!!! It's actually kind of amazing. I've had very good luck sanding with 400, then laying down the clear, untill now.......... my first bout with "solvent popping".

As the wise Homer would say, D'OH !!!!!!!

Burke

[sho305]

I think 2 coats is the recommended from DuPont now that I think of it. You can get away with three though if careful depending on how you spray. I like to do two coats, then add some retarder and immediatly put on another coat with no flash time. Kind of a light coat, but enough to wet it out good again.

On a normal car(not a show car, but nice) I do this a panel at a time with a less retarder, doing the whole 2/3 coat at once, or double-coat; hence the 2.5 total coats. This way I get a half thick third coat with a great gloss and save time. I can do substantial sanding on the amount of clear I get with that. I tried three and ended with more body than I liked, but used thinner coats.

The most I do now: I put the first coat on wet, being very careful not to run it. The second coat I can really pour it on, very wet; then I just re-wet it on the third retarded coat before it is slicked off, or as fast as I can mix it up. The retarder enables you to wet it back out easier too in addition to it still being sort of wet, so the third coat is a little thinner. Used the overall catilyst, with temp recommended reducer(unless a small area). Other people do not put on as wet of a second coat as I, so 3 coats could be the same mil in the end. In my experience, you want to spray the urethane so it looks the way you want it on every coat. The first coat will want to run worse though. So I load it on after the first and slow it down after the second. Depends on the temp too as usual. The overall flows the most, and even it flows little. Slow solvents rule if you can use them right. I painted half a car with some old laquer and very slow thinner once, and only buffed it with a cleaner; not compound and no sanding. Had to have good sealer and no wet base coats under it though or it would swell up any bodywork in the car. The retarder tends to make it flow more, but does not make it slick off much longer really.

Another factor could be the moisture content in the air. It also affects drying. You would be much happier with retarder than extra thinner. I use some old Acme retarder in fact. DuPont came out with some but I never used it much, might have to get some as I am running out. Been doing regular cars lately and do not bother with this unless it is hot out.

If I clear over old CC in a blend, I have to use 2000 to not have it show. Must be with your gelcoat it does not, so you could sand courser than that. On a car I would sand it some then lock it in with catylized primer, then color and clear. I think you need to sand it out, then clear. You can sand it some and try buffing as it might go away, but low chances of that. Retarder will help you level your last coat out very nicely.

I used to think it was better to use more thinner coats, but find I get a smoother result with the above way with clear urethanes. Everyone likes this fast dry stuff now, and it works good on smaller areas. I have even retarded it for a whole car, but still get a better job with overall speed. I pick the bugs out, anything else I can sand. I did a car the first way with the second double-coat and it had dirt in it; but it looked so nice outside I never buffed it. It was only a Ford Contour, and still looks great 4 years later. You can only see the tiny bumps under florecent lights...

Just remember; urethanes are way, way more forgiving of this stuff today than the junk we used to have to use.:)

[Burke Kilgour]

Ya, in the sun, this defect doesn't show up, but I know it's there..............
I learned a valuable lesson on this one, I just wish it wasn't on the bow of my boat !!!!!!!

Burke

[sho305]

Few paint jobs are perfect, is it noticable? If not, keep quiet! This used to be common before urethanes and even worse. Ask any old painter, if you can find a live one...glad I came on the sceen when that stuff was going out. If you must; you will likely have to sand them out or open to fill them with clear. If they go away under water they ought to be gone. Nobody worries about all the times this stuff happens in bodyshops; and they have to fix it for free. Yet here the body book labor rate is much less than mechanical and other professions. So I got out of it. Just do my own stuff now. Sorry for the book sized post, it was raining out here:)

[pantera1]

Kind of a cool affect ..Id leave em ..Not worth the effort:D

[streaming demon]

i am an auto and boat painter first off. what you need to do is take 1200 grit wet sanding paper sand them smooth and then go over that with 200o grit then buff it useing a good medium duty compond and then get good polish and polish it. i would recomend 3M PRODUCTS perfect it 2 compound and and finess it polish the stuff works great for what you need to do or you can just wte sand it with 1000 grit and re clear the bow if you know how with out getting edges if you need any more in fo get ahold of me i would be glad to help.

[Burke Kilgour]

I might just do that, Matt.
Thanks for the info. :D

Burke

[sho305]

Yeah, few people do that stuff anymore. Once I painted a car metallic blue, and I had some red mica(now used for cool new metallics, like a red aluminum), so I painted a junk fender too. Then I put some of that mica in the first coat of clear for fun. It looked neat, but I never had a project I wanted that look on.