Help with a rattle can job

Apis

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Professionals look away now, lol. I'm in the middle of a quick cheap touch up on a 20 year old camper van bonnet. Using Holts white primer in prep for a holts white topcoat. I've used a sander to feather back the old paint in one area. But the now the paint reacts and blisters with the some parts of the old white top coat where I feathered back. Any handy solution for fixing this. The more I sand it away, the worse it gets.thanks
20210714_191319.jpg
 

purplea4T

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A reaction between paint types usually, maybe you're "opening" the existing paint by sanding over it.
 

Coog

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Unfortunately your new paint is softening the old paint. I'm not sure you're going to get it to blend easily. Normally the answer is an isolator but thats only useful for a full panel.

Take it back further and try ridiculously light coats on the already painted bits. If its applied too thick or too quickly it'll go like that.
 

Apis

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Yes, sanding back a bit more and then trying really light misty coats. Seems to be working a bit. I'll persevere.
Did you mist a bit of etch primer over first? I assume you feathered to metal?

Rattle cans are solvent heavy & can react with old edges if you are heavy handed
I was actually trying not to break through the old primer into the metal because I thought that would be better.
And I didn't use etch primer at all, don't even have any. (I do have plastic primer left from old job if that's any good.)
 

KevM

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No, if you didn't cut through to the metal, you won't need etch. It just looks in the pic like the paint had blown up and delaminated in a big bubble. Might just be the pic
 

Apis

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Slow and steady did the job. Not perfect, but white is a very forgiving colour, from a few feet away.
 

DJMCA

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No use to you now but for anybody in the future

I find Hammerite spray very good for solving this, it reacts to very little and covers most surfaces really well. If its reacting when painting parts or similar i use the Hammerite as a base coat and then apply the finish on top
 

Apis

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No use to you now but for anybody in the future

I find Hammerite spray very good for solving this, it reacts to very little and covers most surfaces really well. If its reacting when painting parts or similar i use the Hammerite as a base coat and then apply the finish on top
Good to know, thanks.
 
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