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Old 12-11-2011, 08:17 PM
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Help! Craters / Dimples in my wet sanded PPG Concept

We started shooting final paint on my VW bus project this weekend and ran into a big snag. We took a great tip from forum member Shine to shoot 3 coats of Concept, wet sand with 600, then shoot 2 pretty coats on top. This made a lot of sense for our project since we're not in a fancy paint booth and could possibly get some dust in the paint and remove some orange peel.

So, we shot some paint and while it was friggin amazing we quickly noticed some imperfections which we assumed was dust until we started wet sanding this morning. Shockingly there were a bunch of little craters or dimples after some 600 wet sanding. Included are some photos, one is what I believe is a before shot of a crater (it was still drying so I couldnt be sure)

We did some brainstorming and a couple hours of searching the forums and have a few ideas.

1) Could be Solvent Pop. We're using DX 320, usually shooting paint 10 minutes or so after cleaning. This probably isnt long enough is it?

2) It was much colder then we expected and shot with reducer out of temperature range. We used DT 885 (temp range 75-85) when the temp in the booth was 65-70. The paint store was closed and we had to shoot on a deadline.

3) Is it dirt or water in the air supply? We have a single toilet paper style filter at the compressor and a filter at the gun.

4) Could it be crusty paint? We shot some of the gallon a few months ago and have noticed crusty dried pieces in the strainers when mixing the paint. Im straining now right out of the can and again when pouring the mix into the gun pot.

We need to have the project done in a week, any help would be great. This kinda stinks.
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Old 12-11-2011, 09:23 PM
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That looks like fish eyes!

Last edited by Scm1; 12-11-2011 at 09:27 PM. Reason: Misread post
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Old 12-11-2011, 09:28 PM
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Ok, made another major discovery! We have both DX320 and 330 in the shop and mistakenly used the 330 before paint. Again with only 10 minutes or so from time to wipe to paint.

Obviously a bunch of possible issues...
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Old 12-11-2011, 09:35 PM
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Air dryer

Also clean dry air is very important when painting, maybe an better air dryer water seperater will do the job better. I use an sharpe membrane air dryer and have had 0 problems since, but if your an hobbyist unlike me that's too much money for an tool you'll only use a couple times a year. Besides that your finish looks like a pretty good job and I cant wait to see finish product. Good luck!
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Old 12-11-2011, 09:52 PM
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It is from the grease and wax remover ..

Ajax and plain water with a good rinse would have saved
so much pain... The fix is to sand and recoat but don't sand all the way through as it is sealed now. dust in a brige coat there then go wet, Don't put more grease and wax spreader on there..it hides in pores and will get ya again.
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Old 12-11-2011, 10:09 PM
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Quote:
Originally Posted by milo
It is from the grease and wax remover ..

Ajax and plain water with a good rinse would have saved
so much pain... The fix is to sand and recoat but don't sand all the way through as it is sealed now. dust in a brige coat there then go wet, Don't put more grease and wax spreader on there..it hides in pores and will get ya again.
This could be true the cause of this but, so many variables when not painting in a booth, and not suited up. Lil trick I know of is to mix a Lil clear up and just dab in the craters let cure and buff. It's so small it'll just melt in. Worth a try versus using more material on the panel, don't want to much material on there could cause more problems. Just my 2"
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Old 12-11-2011, 10:31 PM
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The plan was to shoot the first 3 coats, then wet with 600, then 2 more final coats. There so little orange peel, just these stupid craters. It wont be a problem to sand those out and shoot more though I just want to make sure the next coat doesnt have them either.

Milo, can you elaborate a bit on the Ajax? I got one shot at this! lol

Heres a nice pic before the sand!!
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Old 12-11-2011, 11:09 PM
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If those are the only problems there then Scm1 has a good soulution to keep it local with a drop of activated clear or even a drop of activated CLV paint since it's a singlestage and fresh..

Lots of folks have stopped using solvent type wax and grease removers and some companies are even recommending Ajax and water with a grey scuff pad prior to paint. With the water rinse you can watch how the water behaves as the skin breaks and acutally visually check for the comtaminets before you paint,,
http://www.a2zautoforums.com/showpos...24&postcount=4
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Old 12-12-2011, 12:32 AM
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Cant do the clear, I want to keep this vintage 1966.
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Old 12-29-2011, 04:41 PM
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paint problems

OK, i figured this out about 20 yrs ago--same problem. The solvent type wax and grease removers dissolve the contaminants and allow you to move (spread) the contaminants everywhere. These products have caused more problems for more painters than any others. Ajax was my solution back then, on a known clean, soft handtowel. (It can't even be dried in a dryer with fabric softener.) Next came a product named TING. Use it with a gray or red scuff pad. A small quantity goes a long way. Apply Ting if available, or Malco Surface Prep to a wet scuff pad and clean a 2-3 sq' area at a time. Keep surface wet at all times and rinse thoroughly with clean water. Go over the entire area to be painted AT LEAST twice, cleaning it as thoroughly as possible. I do this before ever beginning any body work. I do it again after priming. I haven't had a contamination problem since i started using these products. When prepping a surface for paint cleanliness has no substitute. It is time consuming but worth every minute
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Old 12-29-2011, 07:33 PM
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Another thing I've run accross is contaminated dust. Vehicle clean as a pin.
First coat slick and clean. Then a few specks of dust land in it. The subsequent coats fisheye around each speck of dust. Nowhere else.
Come to find out. prior to painting, while my back was turned, th' boss blew th' dust outta th' shop with a gas powered leafblower. I got fired for the 2 stroke oil soaked dust landing in my paint job.
That's ok He came to realize what he'd done, and I told him to fix it hisself, as I was loading up.
Some of my best paintjobs have been done in an un-disturbed dirty building. and some of the worst have been done in a room that had just been "cleaned".
I use an Accuspray, with a Croix turbine, so there's no moisture, or oil, in the supply. I get the vehicle clean as humanly possible, so the only source of contamination, comes from the air, or me.
Dad has been known to "take the ultimate" precaution, and paint in th' buff. (eewww)

Thanx
Shorty
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Old 12-30-2011, 07:50 AM
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All you gotta do is dab a little catilized paint in the crater...then sand and buff the car..chances are though it'll sand right out without using the paint...
As far as wax and grease remover causing the problems ....not very likeky...but there are crappy brands so buy a good quality brand ,and it CAN get contaminated if left open ...
in your situation though ,improper application or bad W&G is not the case what you have is contaminated dust...caused by a number of things like W-D 40, disel exhaust,etc that sticks to dust and lands on your paint usually in the last coats. a very common problem when painting without a dedicated paint area or booth...if it was a W&G (application) problem it would show up right at the start. another cause is the compressor getting hot and producing more moisture and getting out in the air lines ..also not the case ,there would be much more than that...
using ajax or comet is a great way to prep a car but not to eliminate fisheyes (maybe a little),its for better adheasion (especially around the edges),its much better than scuffing alone because the cleaners are abrasive ....and less dirt because the water washes it all away...When I take the time to wash with an abrasive cleaner I do it outside and using Dawn dish soap and put the ajax directly on the scuff pad then wash the whole car top to bottom..but the very last thing I do when its in the booth is a last wipe down with W&G remover.
I've painted cars that were so drenched with silicone (even under the hood) that you couldn't even get in to move the car without that crap sticking all over your hands and any where that touches it like your pant leg then you rub against something your preping and its all over that, sometimes you cant just dewax once and get away with it ,sometime 4-5 times ,you'll know as soon as you put the W&G on because you can see the fisheyes right then,I'm always amazed at how many pros dont know how to properly use W&G ..YES ,it melts the wax and grease and spreads it around but thats what its supposed to do and only half of it,you have wipe it off while its still wet also.
Using W&G is the proper way to prep...using ajax or whatever is just an added precaution ....
All and all those three little fisheyes are nothing compared to what I've seen done in booths by pros...Thats a good job that you can be proud of...
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