What is the proper procedure to mix an epoxy or polyurethane?

Proportion out components according to parts by weight ratio, accurate to +/- 2%, into a non-reactive container (polyethylene, polypropylene, or metal de-rimmed can). Container should be about five times larger than the volume of the mixed material. Mix components very thoroughly, preferably with a metal spatula, scraping the sides and bottom of container to incorporate all material. If working time allows, transfer material to a clean container without scraping sides or bottom before applying. If working time does not allow transfer, material should be used immediately.