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I have now laid bare a metal frame by following advise in a previous answer. Now I want to remove its white paint coating. I've briefly tried manual sanding (with P180 sandpaper), but this promises only little progress. The sanding is in preparation for painting the frame with a new color. The frame is approx. 60 x 60 cm with its bars' diameters at approx. 3 cm.

What type of grinding machine (for home use) and what type of sandpaper would be best for this task? And how will I know when I'm done before the new painting?

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  • What will you do about priming it? Will it be outside? – Harper Sep 18 '18 at 7:12
  • @Harper I'm doing this type of work for the first time, so I may be naive :) (Always good to learn something new.) I started by inquiring a local hardware store, and they suggested I should try to remove all the paint and then put the color (as indicated in comments below) on, without further priming. This is my current starting point, but it could easily be adjusted. – Drux Sep 19 '18 at 4:53
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You do not need to strip all the existing paint off, though you can fairly easily with a chemical paint stripper if you want to.

You need only to remove the shine from the existing paint; what I call de-glossing, to prepare it for a new paint coat. You should be able to use the 180 paper to accomplish this, but utilizing successively finer grit paper will incrementally improve the look (smoothness, shine) of the new paint.

  • Thx, that's very good news :) Do you think the color I indicated in the comment to the other answer could do the job? – Drux Sep 19 '18 at 4:48
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I do serious restoration work. Heres what I'd do exactly.

  1. Use the 180 (since it's handy, and will suffice) with my hands to go after anything rough or bad on the surface, i.e. Those weird ridges near the holes.

  2. Pay close attention to the gloss of the paint. Use a Scotchbrite pad, steel wool, gritty tub cleaner, whatever, to go over the entire thing and dinge up the gloss so it's not so shiny anymore. That is the goal. No more than that. This is fast work with a Scotchbrite pad.

That's your prep. The ready-for-paint coating is a smooth (but deglossed) old paint.

Next I do a 2-cloth solvent wipedown in the new paint's solvent, also looking for any reaction between solvent and old paint, as that'll nix the deal. Then prime if needed and topcoat. Done and done.

The purpose of the scuffing is to introduce microscopic crags and fissures in the glass-like surface of the old paint. The new paint will flow into these, harden and interlock into them for a strong mechanical bond.


Niw if the piece were much more distressed, I'd use chemical stripppers and turn down the pressure in my media blast cabinet to blast to SSPC-SP10 near white metal.

Mix up a batch of whatever aircraft grade primer EPA will let me spray this week, dab it under the little hooks with a brush and let it dry. Then sand all the lumpy excess from that brush job, hang the piece and spray it with that primer. If topcoat couldn't stick to that directly or needed color assist, another primer: 2-pack epoxy barrier coat, til the surface is uniform, then many dusting coats of spray topcoat to good cover and flow-out.

  • Excellent, but I'm not sure I do get "a 2-cloth solvent wipedown in the new paint's solvent" quite yet. (Also not a native speaker.) I was hoping to apply this color (translation from German courtesy of Google translate). Are you suggesting that I should put a bit of this color on to check whether it enters into an unwanted reaction with the old color? Or do I need an additional solvent/chemical as well? – Drux Sep 19 '18 at 4:46

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