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There's been a bit of discussion amongst the record washing community (if thats a thing) about ultrasonic damaging records. I think the jury's out on that one but there's plenty of little bits of vinyl coming off the trimmed edges or the centre holes that can find their way onto the disk.
The argument against ultrasonic is that it's powerful enough to cause cavities to explode and fracture small quantities of the groove. I guess it's an issue if your are talking about the first pressing of Waltz For Debbie.
Cleaning old records in a ultrasonic bath means you get a residue of black bits..