@antinn Of course you are correct. I guess I was thinking primarily of the rinse. Of interest, there was a thread on the internet about 10 years ago where the author (I cannot remember his name) did a fairly detailed side by side comparison of rinse (only) between IPA and ethanol and concluded that sonically the ETOH was superior. I have adopted that since, but I think it was more opinion and not science based. I mentioned it only because the OP noted that distilled water alone didn't penetrate the grooves. So I guess it's safe to say that adding some IPA or ETOH will likely help with the rinse.
@billstevenson I have used both IPA and ETOH in several different ultrasonic baths without problem. I contacted the folks at Degritter and they stated ETOH was not a problem in their machine, as long as the concentration was below the flash point that Neil outlines well in his book. It definitely improves wetability which I think is advantageous for a final rinse. I have had no problems whatsoever with this approach with over 2500 cleanings and 3 different ultrasonic machines and consider it safe. Also, the cleaning solution for the Clearaudio double matrix allows for ETOH to be added.