Paint Preparation?

Repainting my S3 bonnet and replacing rusting back door. I bought a new back door which seems to be painted with a grey primer. Can I paint over this once I have flatted it out and de-greased it, or does it need taking down to bare metal?
Any help appreciated.
Pikefly

What are you over painting the panel with? I would guess it is some type of 1k etch primer.

I'm getting my 2a ready for spraying in my garage and like you I've just bought a new back door pre primed and sill need to get the 4 front door half's yet but with the back door plan to give the rear door a light rubbing down then re-primer it as the pre priming is very thin

Alfieslandy said:

What are you over painting the panel with? I would guess it is some type of 1k etch primer.

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Yes, etch primer followed by 2x polyurethane top coats.

cornish rattler said:

I'm getting my 2a ready for spraying in my garage and like you I've just bought a new back door pre primed and sill need to get the 4 front door half's yet but with the back door plan to give the rear door a light rubbing down then re-primer it as the pre priming is very thin

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I have flatted out the "shop finish" with 800 wet & dry. I propose to spray that with etch primer and then two coats of polyurethane. I agree with you assessment of the primer as bought it is very thin and easily scratched but I thought it all had to be taken off before any other paint.

Yeah i've bought 3 new safari rear doors over the yrs all pre primed and always done them that way and never had a problem with them so hopefully this one should go the same way

cornish rattler said:

Yeah i've bought 3 new safari rear doors over the yrs all pre primed and always done them that way and never had a problem with them so hopefully this one should go the same way

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Thanks Graham. Working on the bonnet at the moment, just put UPOL on the underside, etch primer next on the top side then paint. The back door is not so urgent but should be done by the end of the month before a camping & off road trip in Wiltshire and Dorset in May.
Youir comments are much appreciated.
Tim

pikefly said:

Thanks Graham. Working on the bonnet at the moment, just put UPOL on the underside, etch primer next on the top side then paint. The back door is not so urgent but should be done by the end of the month before a camping & off road trip in Wiltshire and Dorset in May.
Youir comments are much appreciated.
Tim

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No prob's