I had phenidone and pyrocatechin mixed in blue propylene glycol auto antifreeze. Today I thought that I would mix a fresh batch of pyrocat hd. Problem, I had run out of phenidone mixed in propylene glycol. So I had a search around my garage and found some red ethylene glycol anti-freeze. I warmed up the ethylene glycol and stirred in my phenidone it went into solution no problem. Then I put a measured amount of pyrocatechine/prop glycol in a glass jar I then added a measured amount of phenidone/ethylene glycol in the jar. Disaster! I ended up with a frothy slurry like mixture. Why did my glycols not mix together?