Posted it here originally.
There are keys (push buttons) on the front panel of an avionics device that fits inside the aircraft cockpit. I need to know the material of which those key-tops are made from.
I can guess the material is some type of clear transparent plastic and then its painted with black color. The text on it is un-painted key surface. There is green light under the keys (buttons). That green light glows the text (due to transparent plastic) on the key-top as green in color.
This cockpit device is from a very old aircraft model of 1950's so we can say it is not using any modern high performance thermoplastic or composite material. How can I best identify the material of these key-tops?
Edit: How do I know if the key-top material is compatible with NVIS (Night Vision Imaging Systems)?