Yes, those old Ever-Ready brushes have handles that are thin plastic shells and can melt if you aren't careful. I don't think there would be a problem with a solid handle though.
This is an old Canadian made Simms brush that I steamed the knot out of. Got lucky on the melting bit as they are made the same way as the Ever-Ready ones, with a thin hollow handle. The knot was set in rubber glue and I don't remember if it was salvageable because I was pitching it out anyway. I was a while ago that I did this too so factor in the old age effect too.
Bob
http://i59.photobucket.com/albums/g2...pshzf9oqng.jpg