Making Your Own Ground Glass
I recently modded a Polaroid 120 camera to shoot 4x5 sheet film. The mod included a 4x5 ground glass holder for adjusting focus. The instruction suggest using a frosted piece of acrylic but I wanted to try grinding my own glass. What I found was that making your own ground glass was cheap, effective, and easy. I figured I would share my process and results.
Materials
- Glass cut to size (I'm grinding 4x5)
- Larger glass to grind on (I used and 8x10 sheet of 1/2" glass)
- 25 micron aluminum oxide
Process
- Set the large piece of glass down on the counter, this acts as our "anvil", it's meant to be heavy and flat for us to grind against.
- Put a small scoop (~1/4tsp) the 25 micron aluminum oxide near the center.
- Sprinkle with a small amount (~1tsp) of water to make a slurry.
- Place the piece of glass you're grinding down ontop of the slurry.
- Moving in a circle manner, apply a small amount of pressure on the smaller glass while moving it around the whole surface of the larger glass.
- You may notice that the grit dries out and gets "sticky" and "grindy", if this happens add a few more drops of water.
- At any point you can take the small piece of glass and rinse it off to check progress.
- I would estimate that it took me 10-15 minutes of rubbing to have a completely uniform matte surface
Bonus points: I found that after grinding at 25 micron that the glass was sufficient for my uses. But it seems like another found at 9 micron might produce a smaller grain for even better clarity.
Here are some examples of the results in use:
