I have re-cured lots of eggs by washing the old borax off and re-curing with new borax but I dont know why it wouldnt work going from borax to pro cure, what I do is put my old eggs in a spaghetti strainer and wash all of the old borax off then let them drain for a little while then spread them out on some news paper and let them drain a little longer then I roll them in lots of borax put them back into freezer containers and freez them, works great.