NFT5 wrote:Multiple problems here.

3 coats of filler/primer. Even with 10 minutes between coats, if you left it for a day that probably wouldn't be enough.

3 coats of adhesion promoter? 3 COATS!!!!!??? One mate, just one, thin coat is all that should be used and it should not really be used over painted surfaces. It's for unpainted plastic. Being 1K it's also mostly thinners so even after an hour you had heaps of unevaporated solvent sitting there just waiting to get out.

So then a coat of base. By now you had a ticking time bomb just waiting to explode and the second coat of base was the straw that broke the camel's back. That it didn't fry up even worse surprises me.

Take it all off and start again. This time repair the scratches either with filler or by sanding down and feathering the edges. Then prime, sand and apply base. Wait minimum 15 minutes if you're up north, maybe an hour if in the southern states. Longer is better, remembering that you're using acrylic products and the solvent will activate the prior coat and soften to achieve adhesion. Clear with 1 light tack coat then 2 coats medium wet, not heavy.

Oh, and don't scuff after your base coat. Scuffing should be done either before or after primer. Scuffing base will scratch it and the scratches will be visible through the clear.

NFT5 wrote:One mate, just one, thin coat

hujur wrote:The primer that I used wasn't a plastic primer. It's used only on metal surfaces.

hujur wrote:5. Apply 3 coats of Adhesion Primer (10 mins between each coat)

NFT5 wrote:

hujur wrote:The primer that I used wasn't a plastic primer. It's used only on metal surfaces.

What you linked is Primer Surfacer, which is suitable for all surfaces.

But, what you said, originally, was:

hujur wrote:5. Apply 3 coats of Adhesion Primer (10 mins between each coat)

There is a big difference between Adhesion Promoter (which is what I thought you meant by "Adhesion Primer") and Primer Surfacer.

Anyway, now we're on the same page, the primer surfacer really wasn't necessary over the primer filler (which is basically just a high solids variation of the primer surfacer and a different colour, pink vs grey IIRC).

Being primer surfacer it has higher solids content than the adhesion promoter that I thought you meant, which only made the situation worse - the solids slow down the evaporation of the solvent.

It's a technical world and automotive painting can be a real trap for the uninformed.

Yeah, do it again and should come out ok.

NFT5 wrote:No, mate, not that stuff.

That's enamel primer. Will cause even more problems. What you need is a lacquer primer, which is what you have.

Get your substrate smooth and you should not have to use the primer filler, just the primer surfacer. Sand that with P800 and you'll have a nice surface for your top coats.