WPE is Weight Per Epoxide equivalent. From this value, one determines the optimum amount of DDSA or NMA in grams to combine with 100 grams of resin for stoichiometric balance minimizing unreacted starting materials and producing reproducibly stainable, embedding blocks.
The exact WPE value for each lot of Poly/Bed® 502 resin is put on the lable of each container purchased from Polysciences.
WPE 233-250
MSDS / Technical Data Sheets / Product Literature