What To Use To Display Watermarks

Went to Wal-Mart today and bought a 97 cent pencil tray with a black lid, took the lid off to use as the tray. They were out of Ronsonol there so while at the PX on Ft. Hood I bought a can of Zippo lighter fluid which from what I can see so far works quite well. It's a good thing I did this too because so far I've had to change quite a few of the numbers I have for my German and Hungarian stamps due to watermarks. Thanks for all the helpful hints, much appreciated.

Seeing your use of a plastic pencil tray I was reminded of a person in the stamp store I bought my watermark fluid and special tray from saying that the fluid would eat away at other plastics. You had to use the special tray or a black ceramic tray or dish.

Not sure what the tray is made of or what to be wary of though exactly.