Well, that is surprising to me. I had thought Pyrex was more stable and less likely to have any etching and residue imbedded in the material. I will keep that in mind. I will do some research. I have made dozens of recipes with frozen milks etc, and only had that happen due to the alcohol...
I have made red wine soap. But being the impatient one I am, I thought it wasn't really necessary to boil off the alcohol. But I was wrong! I did get the 'soap on a stick' ! However, I managed to save it, and it's a great bar!
Thanks for all the info here!