Smoothest yet not specular metal or plastic sheets?

In summary, Tom is looking for an off-the-shelf screen material that is smooth enough to not have any noticeable texture when looking with the naked eye from the closest possible distance, but is also not so smooth that a specular mirror is created when projected. He has looked at catalogues and found that most of the materials have a noticeable texture from up close. He has also tried silver nano sized particle powder but hasn't been able to uniformly adhere it to a surface. He has not been able to test etching yet.
  • #36
15,000 grit sandpaper, available from automotive paint supply stores, produces scratches in the 1 micron range, just large enough to disrupt specular reflection of visible light. Cheap and easy to try, just start with full gloss plastic and wet sand. Might have to go with 12,000 grit, but even that shouldn't show when projected. DIY telescope supply stores carry superfine polishing grits as well, but are thinner on the ground than auto paint shops.
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  • #37
Wow. I've seen some 3000 and 4000 grit and thought that was pretty fine. Apparently some people use it to polish chisels after sharpening the edge. Never knew you could get as fine as 15,000 grit.

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