i am in the process of building an ultrasonic cleaner and have tested it on several older records. My findings are superb cleaning with no damage. I based this on examination of the record grooves under a jewelers glass (about 10x power) i can see the grooves ok and i do not appear to see any deformation. Also during playback, i know the record is much cleaning and quieter.
However, i understand the concern as the cleaning action is based on "small bubbles exploding" and hence the concern of chipping the fine layers of vinyl between the grooves. In fact if you perform the aluminum foil test, you will find it will punch holes in the foil. I again know this because i ran this test to validate that my "used" ultrasonic bath was working ok.
I have long been an advocate of steaming/vacuum regime as philjolet referred you to and you will find many of my comments on some of the threads. It is a great way to clean and pretty cheap if you DIY. the commercial units are also good.
but back to your question, i understand the concern, but based on my experience todate have not seen an issue
However, i understand the concern as the cleaning action is based on "small bubbles exploding" and hence the concern of chipping the fine layers of vinyl between the grooves. In fact if you perform the aluminum foil test, you will find it will punch holes in the foil. I again know this because i ran this test to validate that my "used" ultrasonic bath was working ok.
I have long been an advocate of steaming/vacuum regime as philjolet referred you to and you will find many of my comments on some of the threads. It is a great way to clean and pretty cheap if you DIY. the commercial units are also good.
but back to your question, i understand the concern, but based on my experience todate have not seen an issue