Never one to let well enough alone, I did the assignment that I gave to myself after yesterday's PAD - try sand on a glass table top with colored light shining through. Used a clamp light from Lowes with a daylight bulb and a red gel filter. I don't know what I expected to see, but this doesn't do much for me. What to do next?
Fortunately the boss was out and I did this and cleaned it up before she got back (bet you can't find any sand, dear). The table - at least the part that I used - is cleaner than when I started.