How Have You Made a Plastic GG

[Tin Can]

I need to make one.

I easily make glass ones, but have not been successful with plastic.

Tips on correct plastic with sources and how to "grind"?

[Michael Roberts]

I haven't tried to grind acrylic or polycarb, but I have used Gila privacy (frosted) window film to cover acrylic: https://www.largeformatphotography.i...=1#post1498330


I also have purchased the hardware to sand blast a sheet of acrylic using an air compressor and a bucket of sand, but I haven't tried this technique yet.

Interested in any other folks' experiences.

[Drew Wiley]

The problem with acrylic is that it warps or bows, both due to humidity changes and especially due to temperature differentials. There's no need to sandblast it. It's rather soft. Use water or vegetable oil as a lubricant and try various Scotchbrite pads. I know how to use random orbit sanders to do this, but have very specialized equipment, abrasives, and background experience. Not every sander works well, and ordinary woodworking discs do a miserable job. You need discs engineered for plastics and marine finishes,etc, which include Festool blue Granat abrasives, certain Mirka net discs, etc. 3M gold discs work so so; at the present time they're in a joint venture to market Festool abrasives to the auto body trade. Go slow; you don't want to overheat the plastic and start the surface melting. The bigger and thinner a piece of acrylic is, the greater the risk of bowing. This will probably be a minor issue up to 8x10 or so, but could be a distinct problem with ULF sizes. Polycarbonate is stronger than acrylic, but less bright and much harder to properly sand as a focus surface. Removing sharp edges from a cut piece of plastic is best done with a ski file; but you could sand these too. I recommend getting an oversized piece of 1/8" thick Plexiglas-style acrylic for sake of consistent sanding, then cutting it down to final size afterwards.

[Jac@stafford.net]

Just hit a clear plastic with a bit of hair spray. Done!

[Drew Wiley]

Dreadlocks?

[Steve Goldstein]

I've never used this to make a GG, but I did once use a 3M Headlight Lens Restoration Kit for its intended purpose. The first sanding step really roughened things up, perhaps it would do for making an acrylic gg. It's cheap, though not as cheap as hair spray.

The thing I'd normally worry about with hairspray is that the carrier/solvent might affect plastics, but in this case it might actually be helpful.

[Drew Wiley]

It takes very little effort to semi-haze acrylic for gg usage. Grinding down thick acrylic for sake of a convex diffuser, that's a different story!