I'm of the opinion that the "curing" of the soap is mostly about loss of water and to harden the soap. I find that this process is variable based on lye concentration and water as % of oils where less water and higher lye concentration takes less time to "cure". I track water loss vs. time and...
Pyrex is quite safe. Over time, caustic can etch the glass, but this would take literally hundreds of batches before you would even notice and you would likely throw out the pyrex cup before it caused any issues as the glass would become a bit frosted before any problems.
Soap-making-resource Unresponsive
Ordered a mold from them nearly 1 month ago. Despite several messages and multiple emails, I have not heard from them. Their website phone number to call for order help is only a voice mail message and the message box is full - worried about how to get my $$...