Originally Posted by Burge
3. Stay near boiling point: While 'dying' a disc, use a thermometer to stay above 200F(90C), or just keep your pot at a slight simmer. Since you will have evaporation loss at constant temp, make a little scratch at the starting fluid level, of whatever concoction you've decided to go with, so that you can add distilled water as the level goes down. Constant temp will find any weak spots on your masked edge, so be sure to thoroughly burnish down the edges of your design.
I always enjoy reading your posts on dyeing because they come from a more scientific stand point, but i would not suggest keeping the dye at the temperatures that you suggest. i have had 2 discs warped from the dye being too hot and also had a few discs that the dye sort of "burns" the disc and causes it to discolor and do funky things with any sort of bubbles that might form in an attempt to boil.
if your dye is close to the boiling point then when you place your disc in the dye it displaces some of the water/dye so that the amount of liquid between the disc and bottom of pan is less. with that being the case the liquid will start simmering or boiling because there is less liquid to heat up directly under the disc. i watched one guy pull his disc out of the dye and it looked like the surface of the moon. the bubbles from the boiling dye made weird circles on the disc so it looked like craters.
i always heat up my dye until it is steaming nicely then wait 5-10 minutes before i put the disc in now. and i have never had any more problems and the dye sets just fine in most plastics. if a person is patient enough you dont even have to heat up the dye, it just takes a day or two for each color.