Plexi ground glass

[salihonba]

http://salihonbashome.blogspot.tw/20...und-glass.html

[William Whitaker]

Tap Plastics sells or used to sell a product called P95, which was ground on one side and worked well as a ground glass. Tracy Storer should know; I know he used it. Perhaps he'll comment.

[civich]

Sandy,
I dredged this up from a previous thread. It's a very cheap & easily made plastic version of ground glass - I believe it is the same technique used on the wehman & ritter cameras. -Chris

Alex,
If you decide to try a plastic gg for your ULF project here is some info which may be of use.
Transluscent film as described by Jay is available from any art/engineering supply in sizes larger than your 20x20 and in various degrees of opacity. Some comes with an adhesive side but I would avoid these due to the difficulty in eliminating the inevitable air bubbles.
To apply use a 'window film application solution' available at any big box home improvement store and follow the instructions. A hard rubber roller (from an art or hobby center) will help work out the air bubbles.
The resulting plastic ( I used polycarbonate, Lexan brand ) "ground glass" is easily marked with grid lines. Is plastic suitable for your ULF? - dunno - it works fine for my 8x10 and is cheap and in the unlikely event of breakage easily replaced. Is it a quality gg? - for a lot more money you could get something brighter and more fragile but, then again, you will probably not be slinging that bad boy around in a backpack!
-Chris

[Steve Sherman]

If what you are looking for is to put an "etch" or tooth into an ordinary piece of plexiglas so that a focusable image is obtained I would suggest between a 400 & 600 grit sand paper on an "Orbitable" or oscilating sander.

If you intend using sandpaper by hand to effect the scratch than I would suggest something more along the lines of 800 girt paper and water, still in a circular motion.

OR, since this is my livelihood send it to me and I'll put the scratch on the PG per the above for your inspection.

Cheers!

[Tracy Storer]

OK, Will brought me in......there are two acrylic sheet products with "ground" textures ready made. P-95 and P-99.
P-95 is coarse, a bit too coarse, and renders a dark image which is hard to focus on for small cameras, but usable for ULF. P-99s "grind" is too light, and is hot-spot-city, even with a fresnel.
I experimented a bit with loose abrasives, and found it tedious, and would look further into some kind of spray, whether some kind of "sandblasting" or a surface finish. (Satin poly, can give a nice GG effect on plexi, but can peel off)
This is still something I will continue to look into when I have more time, I hate worrying about breaking big groundglass.

[sanking]

Thanks for all replies.

I have some translucent plastic on hand and am going to try to adhere this to acrylic. I did a rough check and it looks like it might work fine if I can get it to stick evenly.

Sandy