Refinishing/repainting prep

I have finished repairing and modifying two rockets from last summer, one was painted with Dupli-color acrylic enamel (rattle can), the other with the Dupli-color paint automotive paint shop system, which is lacquer based and what they call a 123 system. I always prep my rockets with the Dupli-color mastic filler/primer then use what ever system. In the case of the enamel I paint over it, then clear. In the case of the 123 I apply step one prime, then step two the base color then step three the finish or clear.

Both rockets will be repainted using the 123 system as the dry/re-coat times for the enamel is far too long for me.

My question is how far do I need to sand into each rocket before I can lay down my filler primer then paint?

My understanding is that taking the clear off the rocket that was painted using the 123 is all that is required. However the rocket that was painted using the enamel I need to take right down to primer.

I don't like cutting corners so if it is a matter of convenience just to take some paint off but best results dictates removing all paint then I will remove all. But if I can get the same results by doing less work then I am all for it. Besides the process of sanding this paint off really sucks!

I am assuming that the acrylic enamel is solvent based and is actually nothing more than just enamel paint (there was a thread somewhere that got into this). The safe bet is to sand down to primer and then repaint with the Dupli-Color system, which is lacquer based. With patience and very light coats, I have sprayed lacquer over enamel successfully but I give the mist coats of lacquer a minimum of 30 min between coats when I do it and some of them still wrinkled.

If you are certain that the acrylic enamel is actually an acrylic resin, and is fully cured, scuff a small area and give your base coat a try but I would still build it slowly just in case it doesn't play nice with the lacquer. As I understand them, true acrylics cure into a polymer that is solvent resistant and play fairly nice with most other paints once cured.

Tis is just my :2: and could be completely wrong.

Screaminhelo said:

I am assuming that the acrylic enamel is solvent based and is actually nothing more than just enamel paint (there was a thread somewhere that got into this). The safe bet is to sand down to primer and then repaint with the Dupli-Color system, which is lacquer based. With patience and very light coats, I have sprayed lacquer over enamel successfully but I give the mist coats of lacquer a minimum of 30 min between coats when I do it and some of them still wrinkled.

If you are certain that the acrylic enamel is actually an acrylic resin, and is fully cured, scuff a small area and give your base coat a try but I would still build it slowly just in case it doesn't play nice with the lacquer. As I understand them, true acrylics cure into a polymer that is solvent resistant and play fairly nice with most other paints once cured.

Tis is just my :2: and could be completely wrong.

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I am only sure that it was the Dupli-Color Acrylic Enamel, and that the re-coat window was 1 hour and beyond that you had to wait 1 week.

I have re-coated Dupli-color acrylic enamel over Dupli-color acrylic enamel with no primer, as in touch-ups, and besides the colour difference due to oxidation of the clear it was fine. I have also painted over over Dupli-color acrylic enamel with Rusto but when I prepped that rocket I took a lot off, but not right down to primer. Then I re-primed and painted without any issues. But this rocket was a basic two tone rocket and a much MPR.

This time around the rockets are much bigger and or the paint jobs are more involved, so I am trying to confirm the proper procedure before I jump in with both feet.

Well, if you still have some of the rattle can paint you can make a test board. Just follow the same paint layup that you did on the rocket. Make it big enough that you can try the different methods that you are considering.

Something about 5"x7" should work. Once the paint has cured, sand the top half to primer then you can mask off length wise strips to try different techniques for applying the new finish. It will take some time but you can be sure of the final result when you get to painting the rocket.

Personally I would avoid attempting to repaint a rocket with lacquer that was originally painted with enamel. But for some reason, you can spray the lacquer based Duplicolor filler primer over enamel with no problems. I have done that on several repairs, like the one in the link below. This one was originally Duplicolor enamel with no clearcoat and the repair was Duplicolor lacquer filler primer followed by Duplicolor enamel.

https://www.rocketryforum.com/showthread.php?62382-Repairing-cardboard-tube-damage&p=660566#post660566

mpitfield said:

...My understanding is that taking the clear off the rocket that was painted using the 123 is all that is required...

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For that one you don't need to remove the clear, all you need to do is thoroughly sand it. I would use 400 grit. The primer will adhere to it just fine.