Tamiya Paint/Primer not sticking well to metal

[haaammit]

I'm in the process of building the Deagostini Millennium Falcon and decided to put a coat of primer (Tamiya Fine Surface Primer) followed by a coat of AS-20 on some die cast metal pieces of the model. It's been drying for a couple of days but the paint is very delicate, where even a light touch/press is causing the paint to flake.

Any ideas? Do I need to strip back to bare metal and try again? Is there a way to "seal" the paint that's on it? I've got some weathering to do to the pieces and am worried the paint will peel/flake even more when I start.

Any pointers gratefully received!

 

[haaammit]

Thanks for the replies. I spent an hour and a half or so removing the paint/primer so I was back to bare metal. It was very easy to rub/scratch off, if a little time consuming

I degreased the parts using a heavy duty TFR (Traffic Film Remover) and left them to dry. I've re-primered one piece to see if it sticks any better - if not I'll look to get another primer. I do have air brushes, so that's not a problem. The Vallejo Surface Primer Acrylic is what you'd recommend @robfosters ? @vanpeebles I'll try an automotive primer if the Vallejo stuff doesn't work as well as I'd like.

Thinking on it I wonder if there was a release agent on the parts to get them out of the mould? Will see how the Tamiya stuff works this time round with fully cleaned bits (Only done one bit to test before fully committing again!)

 

[haaammit]

Just to update this thread: Repainting one test piece was a bust, even after degreasing etc. Luckily only did one test piece. Seems the Tamiya stuff can't get a good bite on the metal. Took it back to bare metal and tried something else.

I bought some U-Pol etch primer (as this doesn't need primer filler apparently) and tried that on the test piece. Two coats, waiting 5 mins in-between coats for it to flash off, then two coats AS-20 rattle can sprayed after 20 mins of drying time. Left alone for 24 hours to fully cure and I had a nice, robust finish.

Two coats of primer and two coats of colour on the rest of the pieces this morning and a 24 hour cure time and hopefully tomorrow I can assemble the bits without the paint dropping/flaking off!

Many thanks for the ideas/pointers/advice