Sunday, July 21, 2013

Optical finish for acrylic -- vapor polishing and other techniques

I needed to polish two acrylic lenses that were made on a CNC lathe to the best possible finish (hopefully, optical quality). I made some test coupons and tried three different polishing techniques on three different surfaces to see which combination of techniques would yield the best results. The winner was clearly 2000 grit sandpaper followed by Novus No.2 polish.
Vapor polishing
 http://www.youtube.com/watch?v=bduno3eafcc

2 comments:

Anonymous said...

Your page came up on HACKADAY.com.

How does using Brasso compare to this method?

Anonymous said...

Great video! Lots of good information. I used to build display cases for museums and tradeshows and came to pretty much the same conclusions, although haven't tried the vapor polish method. Flame is better for edges, and makes it shiny, but distorted. Rubbing compound gives the best result, but is slower. Of all the buffing compounds I've used, both solid and liquid, in my opinion, Novus #2 gives the best finish, although you can do bigger areas faster with a soft wheel and solid compound.

I've noticed that Novus #2 cuts faster when it's a little dry. If you let the water carrier in the polish evaporate out a bit and then lap the part on a flat surface -- I use the back of a sheet of 600 grit sandpaper on glass -- I can achieve a great finish without going higher than 600 grit. The sanding marks are still visible, but the haze completely disappears and the plastic is transparent, with just a little distortion.

Thanks again -- great work!

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