For best results, the edges of the acrylic need to be as clear and as smooth as possible so they will let in the maximum amount of IR light. When you buy acrylic, it comes very rough because of how they cut it in the shop. So I decided to, first, sand it with 220 grit then 400 grit sand paper.
Before the process even started the edges of the plexi glass looked something like this:
After using an electric sander with the 220 grit sand paper, the plexi glass looked something like this:
Unfortunately, with my camera, its hard to tell whats smoother than that from here on out. When sanding I had to be very careful to keep the sander level with the side of the glass. Also, I had to be careful to not stay in one spot for too long sanding, or else the glass wouldn't be level all the way across.
I went over each side with the 220 grit about 10 - 15 times each, and changed the sand paper every 2 sides. When I went to the 400 grit wet, I went over each side about the same amount, but every 2 times I stopped to get the sand paper wet again, and the glass wet again.
After each sanding session I wiped the glass down with a wet cloth to get any excess dust off. When I was done with both 220 and 400 grit sanding, on all sides, I wanted to buff out anything else that was left. To do this I found a buffer laying around my house and some polish.
I globbed on the 'scratch out' onto the glass, smeared it around, then let it dry. After about 5 minutes of drying, I buffed it all out, then wiped it down with the wet cloth.
Well, I got it extremely shiny! It should work great for the LED's.
