Whoops! I have washed a LOT of buttons over the years and this is the first time I had this happen. The water wasn't especially hot, just hot tap water that I could put my hands in. The Bakelite smell was REALLY strong so I think it might have been these three. Maybe there is something about white Bakelite??
They are all clean and sorted and put away so I'm ready for more. It was a good time!