Record Cleaning Using Vacuum Machine for Cleaning and Ultrasonic for Final Rinse

@orthomead,

Below is Figure 39 from the book that shows the change in surface tension of Ethanol and IPA.  There is not much difference between the two.  To get an appreciable surface tension decrease about 5% is required.  The record surface tension should be about 36-37 dynes/cm.  Getting the water surface tension close is enough to 'wet' the record.  

 Figure 39 – Water + Alcohol Surface Tensions of at 25°C from PACVR
(adapted with permission copyright 1995, American Chemical Society)

 Data for Figure 39 is from “Surface Tension of Alcohol + Water from 20 to 50°C”, Gonzalo Vazquez, Estrella Alvarez, Jose M. Navaza, Journal of Chemical and Engineering Data. 1 May 1995.    

Leaving the record slightly damp from the Teritol cleaning in the VPI seems to provide the reduction in surface tension in the rinse step in the HumminGuru.  Alternatively, the surfactant that is supplied by HumminGuru is also effective.  In my opinion, the addition of IPA to the US machine is not a good idea.  My thought process is a) it is not necessary and b) it could need to be in a higher concentration consistent with safety.

@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.

@billstevenson

OMG, I've just realised that US means Ultrasonic, not useless or United States.

Also any concentration of ethyl alcohol above 5% should be hitting the back of one's throat!

@antinn 

Now that I am satisfied that ultrasonic cleaning leaves my records better than they were (except for one new one I managed to scratch) I am happy to try to make them even better.  Will follow your suggestions more thoroughly!

Will even try secondhand!

Cheers