If you're using ultrasonic cleaning, chlorethelye is a good cleaner. You can use alcohol too. Ultrasonic can damage parts if left in too long (will actually totally disintigrate aluminum). Parts that rub together in an ultrasonic cleaner will damage each other. Degreasing is better acomplished in a vapor barrier, rather than ultrasonic cleaning. Ultrasonic cleaning is very successful for parts that have intricate passages throughout that are not readily accessable. Electosonic cleaning is also effective for low depth cleaning using alcohol, but you must not use a wire basket, and be sure that all parts are separated to prevent rub damage.
Remember that some parts in a 1911 are precision machined surface finishes, and any rubbing, at either ultasonic or electrosonic frequencies may well damage the parts.
PS: DO NOT PUT ALCOHOL IN A HEATED CLEANER...
I wish this had spelling check....LOL
Really interesting....Don't ya think??