the 58 p/u is almost ready to be put on the road and I was in the process of buffing the bc/cc and on one fender only, a million white dots appeared very small in diameter, the paint is sherman williaims, same with the clear, this did not show up while wetsanding with 2000 grit but as soon as I started buffing they appeared, I figured I had messed up the clear coat some how, so I took to it with 1000 grit and over it again with 2k pin points still there. so i rally roughed it up wwith 400 and they are still there, I plan on repainting the one fender as none of the other areas were affected.... my main concern at this time, does it need to be taken to bare metal qr just sanded with 400 and resprayed with color and clear??? any ideas?? this is a garage job also....... MikeB
Solvent pop? http://www.sherwin-automotive.com/reference/troubleshooting_guide/solvent_popping/index.cfm
It really sounds like solvent pop. Multiple coats sprayed in hot weather can easily cause it. Not sure it you could get it to stay gone without stripping but you might want to re shoot it and see before going to the trouble of stripping. I have also heard it can be a problem over sandblasted metal but that was with PPG.
Put it in the sun for a day, lightly wet sand with 1000g followed by 1500g, compound and see what you have got then. Sounds like you started before the clear was fully cured.
I just finished shooting S/W clear and had the same problem in an area, color sanding/buffing will typically not solve your problem as it is actually little microscopic craters that have to be filled in. I ended up waiting for the paint to cure and sanding it off and starting over in that particular area....the issue is that your paint top coat is drying too fast forming a skin over the still tacky/wet undercoat and the solvent has no way to burn off, therefore it pops producing the pin head holes that you are seeing. To combat that slow the process down by using a slower reducer. Granted not too optimum if your working in a non-sterile invironment (read garage) however I cleaned the hell outta my workspace and have gotten good results slowing the process down. Like the other bloke posted the trouble shooting link for S/W, read it and learn it it'll save you some trouble in the future.
I think you cleared too soon, that product dries to the touch in about 5 minutes, how long did you wait to apply your clear?
Another vote for solvent pop. Start out as bubbles, until they break, and leave a ton of tiny little pinholes. Caused from the top surface of the paint skimming before the flash solvents have had a chance to escape, then they break thru the surface. Real noticable when compound gets stuck in the pits on a dark colored car. And usually seem to be deep enough, that in attempting to sand and buff them out, you end up going thru the clear down into the base. Some causes, hot weather-too fast of a reducer for conditions, Piling on heavy coats without enough flash time between, too much airflow over the surface. Also a cheaper enamel based basecoat is even more important to plenty of flash time, they are slower to cure, ie omni, limco- and dark colors such as black are slower. Not sure what sw product you used. Humidity will also slow things up. May be a little overkill, but to be on the extra safe side, if say shooting an enamel base in a dark color like black, Apply your base coats, allow to sit overnight and clear it the next day. I say if you have appropriate speed reducer for conditons, have allowed good flash times ect, A slow basecoat can be a big cause of the problem. I remember many years ago now, I worked at a place that rebuilt wrecks, and used cheap omni and limco products. I always had problems with the limco base and clear when spraying a black car. I"d usually get some solvent pop, specially in the center of the roof where tended to apply heavier and had overlap from painting both halfs. Now knowing a little more about paint then then, I understand why. Dark color, cheap base, heavy application, only about maybe a half an hour between applying the base and clearcoating. You will have to sand them out, and that often means going down into the base to get rid of them. That can bring up whole other issues, like lifting on recoat with solvent getting under the edge of broken thru clear. Probably be safest to shoot a little primer on the area if thats the case, and avoid headaches. Also what does the product data sheet say on your base and sanding. Most I have not had a problem sanding the basecoat. I am not a user of dupont or sw, but there was a big thread on dupont chromabase, and sherwin williams products on hotrodders awhile back, How they recommend stripping it and how sanding the base too much can cause delamination problems. If thats true, I'd find a different base, as there are a lot of other good bases that don't say this and say you must strip if you run into a problem nor have I noticed a problem sanding them. http://www.hotrodders.com/forum/interesting-test-sanding-base-coat-paint-against-data-sheets-recommendation-110339.html So I guess I personally would try sanding them out as much as I could, trying not to break thru the clear. Then if you still have some pits, some 2k spot putty or better a little primer and sanding to fill them. Also would not hurt just to be on the safe side, to break open the surface-which you have I ***ume sanding and buffing, and let it see some time out in the sun, just to help any solvents that may be in there get out, to lessen the chances of it happening again when you repaint.
without seeing it i have to go with the rest. solvent pop. it ****s but still happens. if you haven't gotten through with 400 it could have been pin holes in filler. the sealer bridged the gap and the solvent from the bc didn't let them fall until the clear started to bind in. just a thought.
Solvent pop.... you have opened the little bubbles. Simply take a small artist brush, dip the brush in freshly mixed clear, the same clear you used when you sprayed the car. Fill the dots with clear and let dry over night, sand and buff the clear where you fixed it. DONE.
Yep, solvent popping!! The way I have dealt with these is to clean the panel down, make sure no compound is in the microscopic holes and then way over thin some clear with slow reducer and apply one really light coat of clear. This will help 'soak in" to the holes and make any sanding residue disappear, same as they do when you prepsol.If you dont do this, 10 - 20% thinned clear can sit over it and not soak in and you will be left with a white dot under your clear. Then apply a coat of clear as per normal. You will probably get heaps of little craters that look like silicon holes but they are not, it is the clear flowing around the hole rather than flowing over. Simply brush touch these, though it will try your paitence if theres heaps!! Then another coat of clear and sand and buff!
thanks to all, I think I cleared the base to soon, should have waited an hour or so before shooting, on ward and up ward, just nother set back MikeB
I had the same problem several years ago when the shop I worked for switch us to SW from PPG. Found out SW primer surfacers were VERY sensitive to flash times between coats. You couldn't see the pinholes till the clear was on. I hated the stuff, had to wait 30 min between coats, by then it was gelling in the gun, had to mix a fresh batch for every coat. Since you have the problem in just one area by chance did that area get a little more of primer then the rest? If so, you'll probably have to reprime the area to get rid of them.
I have to agree, with the Solvent pops... its possible the clear over the base was applied way to soon to each other.. or the second coat of clear was applied to soon.. either one will create solvent pops at the end, its the solvents trying to escape.... all is not lost though.. wet sand a reclear.. hope it works for you..
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