Base coat ruined from?

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PostPosted: Tue Dec 17, 2019 10:19 pm
NFT5 wrote:Although it's 1K, that sealer is designed for wet-on-wet and after 72 hours needs to be sanded and re-applied before basecoat.

So, it seems your application method was incorrect. It really is important to follow the TDS to the letter with these new products. They're awesome, but not so forgiving.

Sand it all back until smooth. Re-apply a single wet coat of the sealer, wait 15 minutes and apply your basecoat.

Keep your coats light. The sealer should be only just wet on application. Basecoats should be light and even. I note there's quite a bit of texture in that picture, which would indicate overwet application.



Thanks again! I will repeat everything. I screwed it so bad!

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PostPosted: Wed Dec 18, 2019 6:18 am
You're welcome. And don't worry, one day I'll upload some photos of my stuff ups. Not one of us is immune. :wink:

Edit: Nah, this will make you feel better. :happy:

2019-05-07 21.42.06.jpg


That's basecoat that caused the reaction. Notice, though, how flat and smooth the basecoat is elsewhere. No texture like yours.
Chris



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PostPosted: Fri Dec 27, 2019 10:46 pm
Hello people,

I sanded and sprayed everything again. This time, I did not use the wax and tar remover. I have been careful to not spray too much paint and as I have been suggested to do really easy layers. It worked! Thanks again!



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PostPosted: Sat Jan 04, 2020 10:52 pm
NFT5 wrote:This is a reaction between the thinners in your applied coat and something underneath that is sensitive, usually a two pack product, often a primer. It is exacerbated usually by the thinners in basecoat which tend to be a bit more aggressive, which is why it didn't happen with your sealer coat, and heavy applications of each coat which allow the wet paint to soak on the surface and react, instead of flashing off quickly
.


Just after a little clarification, are you saying its possibly a reaction of the thinners that occurs on top of two pack products or the application of two pack products over a prone substrate.

I am only asking as I read your response as it being the first option, i genuinely thought once a two pack product has cured its pretty well impervious to any other finish over the top of it especially thinners.

I have defintely had this happen before :), that is the wrinkling of the applied finish.

Steve

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PostPosted: Sun Jan 05, 2020 2:20 am
Almost always the problem occurs at the feathered edge of a two pack primer. It can happen when spraying on a 1K primer but not usually because of the high solids content (exclude spray cans since they're very low solids content). Two pack primers don't usually cause the underlying feathered edge to fry up because they have low thinners content and it's the thinners that causes the problem.

Base coat, however, does cause frying up since it is anywhere from 3/5 to 1/2 thinners. High quality base coats like the Cromax 6000 tend not to create a problem since they are low (around 30%) thinners.

So, definitely the application of high thinners content products over exposed two pack edges. The thinners softens and gets under the reduced thickness edge causing it to wrinkle. Where the substrate is full thickness and you're applying product over the whole surface it has the thickness and isocyanate induced hardness to resist attack. Exceptions to this are some iso-free clears, which fry up severely and some thermoplastic resins, most commonly used on plastics on older Korean cars and plastics (especially door handles and mirrors) on VT-VZ Holdens. Only solution in these cases is complete removal of the old paint.

Epoxy sealers and the new 2K undercoats can reduce the problem, but they also contain some thinners and should never be applied heavily. WoW is not a good idea if you have a known or suspect substrate. Let that sealer cure first to give you a layer of protection. After that you can apply another coat of epoxy and go WoW with topcoats if you really want to.
Chris



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PostPosted: Thu Jan 09, 2020 5:08 am
When you go a blow out like your photo above on the white base coat, after removing all of the crinkled finish and repairing do you have to re base coat the whole car / panel

Steve

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PostPosted: Thu Jan 09, 2020 3:04 pm
No, just the damaged area and blend into undamaged area(s). Then clear whole panel.
Chris



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PostPosted: Sat Jan 11, 2020 1:36 am
NFT5 wrote:No, just the damaged area and blend into undamaged area(s). Then clear whole panel.


Thanks chris,

I have received a wealth of info from the generous people on this site, so first please do not take my questions as a question on the info supplied but as a question of my lack of understanding.

If you have base coated the panel and get the blow out, after repairing said blow out, if not re base coating the whole panel how are you achieving a good bond to the subsequent clearcoats?

Steve

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PostPosted: Sat Jan 11, 2020 7:03 pm
No problem, Steve. One of the things I like about this forum is the free exchange of thoughts and experience and how both amateurs and pros can work together on something that we all share a passion for.

For me, once a car is in the booth any issues that crop up have to be dealt with before it leaves, so the question of leaving base coat uncleared too long doesn't really arise. If I get a fry up then I have to fix it immediately, before clearing.

That said, if I'd already base coated the panel and some of it fried up I'd just fix it and blend the fix into what I'd already covered with base. Being the same paint there would be no colour issues. If, for some reason (unlikely), I had to leave the base beyond the time that it should be cleared then I'd just lightly scuff the whole thing with P1200-P1500 dry and extend the second layer of base as far as I needed to go. Base coat will adhere to base coat this way, so long as you're careful not to tear the previous coat.
Chris



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PostPosted: Sat Jan 11, 2020 10:58 pm
That makes a lot of sense, you have cleaned a paint booth, cleaned the car spotlessly, suited up etc etc, get a blow out you dont walk away from the car for a day you fix it there and then,

Dooh :knockout:, so obvious ps i just liked the emoji and had to use it
Last edited by simso on Sun Jan 12, 2020 6:20 am, edited 2 times in total.
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