If you want all the details, go to Wikipedia for the chemical composition etc etc.
For our purposes, melamine is a thermosetting plastic which can be compression molded into useful household items, like dinnerware, trays, and utensils.
Melamine plates can be washed in a dishwasher or handwashed.
They should not be used in a microwave since the plate itself heats up.
Our plates are 10 inches in diameter and a medium weight.
Most of the melamine plates on the market are lighter weight and made in China.
Melmac was a popular brand of melamine that appeared in the 1950s.
Older melamine is collectable and you can find lots of examples on ebay.
If anyone has more background information on Melmac, we'd like to hear about it.