Bubbles forming under freshly layed k36

[copasspupil]

I would like to start by saying I am near the finish stages of priming for painting next week hopefully. I have applied the following: dp90 then multiples layers of K36, sanded it down and applied dp90 last week. Today, I applied k36 again to sand it down with 400 for next to final stages of priming and noticed bubbles forming under the k36 all over the place. I used dx330 three times prior to k36 on th entire car, allowed it to dry then shot k36...

What are the bubbles from? I cleaned the guns used prior to use today, but other than that. No change to my approach...

Any help would be great.

Thanks,
Danno

[Harry Phinney]

Could you post a picture of these bubbles? When you say you used the DX three times and let it dry, exactly how did you apply/use the DX? When you cleaned the guns, what did you clean them with? Why did you clean the guns just prior to using them, as they are generally cleaned immediately after use?

Harry Phinney

[70Deuce]

The same thing happened to me. It was on my first coat of K36 over DP90 on my hood - tiny little bubbles everwhere. I can't answer your question but I made a rookie mistake in mixing 4:1 instead of 5:1 and I think that was the reason for my problem. I didn't worry about it too much because I'm at the beginning of the primer stage. I curious to see what more experienced painters say.

[TurboCharger]

Do you need the K36 over the DP90?

[TurboCharger]

Here this should help...

http://www.ppg.com/cr-refinish/phase1/frmSelectDefectGroup.asp

[copasspupil]

I used dx330 and used many lint free throw away towels to clean off the dp90 prior to priming with k36. I had on multiple latex gloves during the cleaning process and painting.

Guns were cleaned pre and post priming. Pre cleaning since they had been sitting for some time and didn't want anything to screw up the priming. Post cleaning was normal stuff.

Lacquer thinner inn a 5 gallon container with pump.

I'm going to go out and look at it later today and see what it looks like. Since I'm going over the car again with 400, I wonder how much will be left to see after.

[dcrog]

Just to clear up the picture in my mind, why did you clean the DP? You also said that you applied the DP last week. Were you still within it's seven day window at seventy degrees?

I ask because DP and most epoxies are designed to be recoated within their recoat windows without sanding. The idea being, in my limited chemical knowledge, that the coating going over it will be more or less absorbed into the epoxy and combine with it to make a stronger bond. Maybe this is a simplistic view of how it works but it is the general idea.

Perhaps the epoxy absorbed the mineral spirits and other chemicals in the cleaner and that is what is causing the bubbles. I could be way off but this seems like a possibility to me.

[copasspupil]

I see your point. I cleaned off the dp90 due to my 4 kids under 7 who may have placed their fingers on the car during the week. I did not want to take a chance of contaminating the surface so I clean it off. I sanded the car down and had to reshoot the high build. It worked out fine for the most part. I need to spray a little bit more on Monday and do a little more sanding then.

[Phil V]

I don't think your bubble problem had anything to do with the DX cleaner, I've never seen that problem before related to a wax and grease remover. What you need to do is take out your pocket knife or a get a razor blade and cut out one of the bubbles. Look close on the bottom side of the bubble to see what the root of the problem is, what actually caused the adhesion problem.

Those bubbles are a BIG red flag. Even if you sanded down those bubbles flat or they appear to settle by themselves there is a good possibility that when you pull the car out into the hot sun that primer will bubble up again like a 14 year old kid with a bad case of acne. You will only compound the problem if you continue with the project as is. There is no alternative but to sand down to the base of all the bubbles, figure out what caused them and go forward from there.

[copasspupil]

I removed all the bubbles when I sanded the car down with 220, 320 then dx the car again 2x then reshot the k36. No bubble appeared after. I talked to my paint supplier and they said it was either water or solvent. Since I had not had that before and drained the tank out prior to spraying, I doubt it was water but solvent maybe.

The bubbles did not adhere to the dp90. When I removed the head of the bubble, it showed the black of the dp90 only.

[ding]

just curious as to why you used dp90 between coats of k36?

[copasspupil]

I was told to do so by a painter friend of mine. I had to apply the dp 90 since I was down to metal in some parts and it allows me to see how many coats I'm removing when a block sand.

[Chris L]

That is a total waist of time and materials.Apply your epoxy,then once its flashed off,apply your 2k and guide coat and sand it.

[bigrob24_7]

ive had body guys tell me not to use the black dp primer. it has adhesion problems....only the black though

[Charlie]

...apply your 2k and guide coat and sand it...

Went to the supply store yesterday, and the jobber told me I have 24-hrs to top-coat the 2k after sanding. I'll never get the whole thing sanded in 24-hrs. Do I shoot another light coat of the 2K after sanding and leave it until I get it top-coated, and then have the shop sand and do the topcoat (enamel) ? I'm just looking to put some color on it; it's just gonna be just daily driver for me...

[Phil V]

Charlie, the guy at the paint store was wrong in telling you that 2K primer has to be topcoated within 24 hours. Technically 2K primer can be left sanded indefinately then topcoated with more primer or topcoat paint. There is no time window with high fill primers. He may have been confused with epoxy primer which DOES have a time window and must be covered in a certain amount of time (different brands have longer or shorter time windows, anything from 24 hours to a full week).

[Charlie]

Thanks. That makes more sense and sure makes things easier. :)