43 replies to this topic

[panelbeaterpeter]

I don't actually agree with any of the ideas above firstly it's not silicone, plus WD40 doesn't even contain silicone, and never has done, although it's not the best thing to have around bodywork as it will cause problems if it's in the air. It looks like a chemical reaction, which is usually quite tricky to track down. Applying a coat of primer after the first has dried won't make any difference IMHO, you can leave it as long as you like, although ideally like Jack said, it should just tack off, it will start to go matt, then it's ready for another coat. If you put the coats on too quickly, the solvents in the primer can soften the material underneath and cause problems, plus the primer can blister caused by the solvent trying to escape through all the layers. If I were you, I'd flat back most of the primer til it was all smooth and there were no edges, then apply either barcoat or a 50:50 mix of 2k hardener and thinners, applied very lightly, like etch primer. should sort out any problems. If it reacts after that, it's probably a problem with your primer.

[midridge2]

" i dont actually agree with any of the ideas above" what, not even mine?
still not said if he used panel wipe.

[james962]

Thanks for replying,

when you say to flat it back, do you mean to remove the blisters and bubbles and to leave the rest that is visibily sound?

we have sanded back these areas before, and then re-primed it with a different primer, zinc primer. Some of it was alright, it appeared to cure the problem, but then some went like this:



The bit in the picture that peeled up was actually the primer applied yesterday. It peeled after we sanded down and re-primed an area that had blistered just under the headlight. This blister had appeared at least 20hours after the primer was applied. We rubbed the blister down smooth and re-primed. And within minutes, the peeling in the photo appeared.

You can also see in the photo that there is a small amount of peeling in the seam, and this occured with the peeling round the headlight.

Would you still recommend to smooth it down and apply 50:50 2K hardener and thinners or to sand down the lot and start again?

I'm abit worried about the rest that looks visibly sound and wonder if this will start to blister in the future.

[james962]

oh, and i haven't used any panel wipes. instead it was wet and dry'ed with plenty of water and detergent. Then rised and dryed off

Edited by james962, 27 March 2008 - 10:38 PM.

[panelbeaterpeter]

" i dont actually agree with any of the ideas above" what, not even mine?
still not said if he used panel wipe.

Oh my apologies, didn't actually see your post in there! Oh whilst I remember, that waterbase paint you were asking about is called 420 topcoat, and is made my Lesonal.

[panelbeaterpeter]

oh, and i haven't used any panel wipes. instead it was wet and dry'ed with plenty of water and detergent. Then rised and dryed off

What kind of detergent? could be caused by that. I hope you didn't use washing up liquid, it contains salt which will speed up any corrosion.

Going by the picture, the primer is not sticking. That could be caused by the existing coats melting underneath the primer, or water coming out of the seam. Did you blow out all the areas after you rinsed it off?

[james962]

Sorry to mis-lead, but instead of detergent we used soap

All the areas were definately dry. We used the heat from a lamp

[panelbeaterpeter]

Sorry to mis-lead, but instead of detergent we used soap

All the areas were definately dry. We used the heat from a lamp

Hmm seeing as you're only getting problems around lips and seam edges, I think it's most likely to be water creeping out. It's very difficult to get rid of all the water when you've been wet flatting, even if you blow it out with compressed air. That's one of the reasons modern body shops on dry flat.

[midridge2]

thanks pete, will do a google on that for more info.
when we say flat down, it means flatting the primer, not rubbing it all off.
any loose primer will come off when flatted, then wipe over with panel wipe and spray with bar coat, that will isolate all the primer underneath and stop any further reaction.

[james962]

thanks for the information, both of you.

I will have another crack at it at the weekend, and i will let you know how it goes.

thanks for your time, james

[matty135790]

I had so many paint isues in my little garage, reactions, cracks, runs ect. once we had 2 patio heaters and a radiator in the garage it seemed to go all right. We also kept the paint at a warm-ish temperature!

Hope that may help ya

[jack_marshall]

Personally Id stop cocking about trying to make the best out of a bad job and start again, doing it properly.

Im worried you will manage to get it into paint only to have problems later down the line.

Personal opinion.

[jonny d]

Personally Id stop cocking about trying to make the best out of a bad job and start again, doing it properly.

Im worried you will manage to get it into paint only to have problems later down the line.

Personal opinion.

I also agree with that, you will get problems further down the line if you try and paint over that paint after flatting it. my opinion

[panelbeaterpeter]

That would be the ideal situation, but it's alot of work to remove the primer when chances are, if you flat it down and apply a coat of sealer or barcoat it'll be fine.

[Southy]

I had this problem when i repainted the front end of my mini last summer and i tried for ages to get the primer to settle but just wouldnt went through like 2 litres of primer in the end and all came back off.Went down paint shop and bought 1litre of barcoat think for 15quid sprayed it on then a coat of primer flatted this down and then basecoat and didnt have any problems what so ever afterwards.