Originally Posted by
PromptCritical
I use one of two solvents in my Ultrasonic cleaner. Either Acetone or Tyme (a freon (legal) derivative). The acetone is used for the easy stuff as it's cheap and can be filtered and reused. The Tyme for the difficult stuff.
Do not put volatile or flammable solvents into an ultrasonic.
Ultrasonics lower the vapor pressure and greatly increase evaporation rates. (how room humidifiers work) This means that any fire or toxicity hazards are much worse.
There are safe ways to use flammable solvents in Ultrasonic, sometimes called the "double boiler" method. The manual that came with your machine should cover this.