Thumbs up for ultrasonic record cleaning

@terry9 

First the R/ = shorthand for Respectfully, and I noted an error in post - meant to "... the stylus does contact..."

In precision cleaning, the industry standard for water is ASTM-D1193.  Once we get past tap-water, ASTM-D1193 has essentially 3 classes of water, Purified (Type 4), Pure (Type 2) and Ultra-Pure (Type 1) and theses are generally specified by resistivity - ohms (or its inverse - conductivity).  You can get on the web and find TDS to resistivity conversion charts, but 30 ppm TDS is equal to about 20K-ohms.  Definitely way better than 200-ppm tap-water, but this is how it compares:

-Purified Water (single step distilled, demineralized, RO) = >200K-ohms
-Pure Water (two step distilled & demineralized) = >1,000K-ohms (1M-ohm)
-Ultra-Pure Water (generally about 3-steps) = >18,000K-ohms (18M-ohms)

30 ppm water that is about 20K-ohm is fine for cleaning, but is a bit short for the final polish.  The purer the water, the more aggressive it becomes believe it or not, and of course the less residue.  Ultra-Pure water is used to clean semi-conductor chips, but it can takes weeks for the applicable system to clean themselves to the point that they are clean (i.e. system commissioned), and has no application here.  Even Pure Water is a stretch, but Purified Water for the final touch/polish should be the goal.  

That being said, in the past (now retired) I have approved Navy cleaning procedures where the final polish was only 50K-ohm, and it was acceptable, but the particulate cleanliness was not critical, anything less than visual was not a problem.  But very small particulate and salts/mineral residue is an issue here, so, my recommendation for the final polish would be Purified Water (distilled or demineralized) to get the best results.

R/Neil

Thanks Neil!

@terry9 

Sometimes you have feel just like an idiot, let me try this one last time, I meant to say "...the stylus does NOT contact...".  Always good to be humble.

R/Neil

@antinn 

So good to have a technical conversation free of snake-oil. Thanks!

I was wondering about your step 1: a fresh, low concentration bath for each cleaning session.

I use 80KHz near the maximum temperature for vinyl (45C), at a 2.5% solution of VersaClean, and, IIRC, a hint of oil can remain after 15 minutes, or even 30 minutes, even for the first pair in the series. This leads me to question a low concentration of surfactant.

But it could just possibly be bad memory. Your views?

@terry9 

The Fisherbrand™ Versa-Clean™, is a broad-base cleaner, with a combination of surfactants and corrosion inhibitors and some alkalinity, and the recommended concentration for use is not less than 60:1, but as much 10:1.  The product details are pretty limited, and although it says concentrated, it is actually a diluted form of very concentrated surfactants.  There is no way to know if a 2.5% solution will achieve the lowest surface tension.  So, 2.5% (40:1) may not be enough, but its not cheap.  And what is IIRC?  When you say a hint of oil are you talking about oil as the original contaminant on the record.  

The Tergitol 15-S-9 that I use for a cleaning solution is very similar to what the US Library of Congress uses to clean delicate shellac records, and is a non-ionic water soluble surfactant.  It is a replacement for Triton X100 that you may often see discussed in these forums, and has the same performance, but at 1/3 the concentration and is not an evironmental hazard.   Tregitol 15-S-9 is very concentrated and is quite cheap, a Qt is $38.70 and at about 4ml/gal https://www.talasonline.com/Tergitol-15-S-3-and-15-S-9, would make about 250 gallons of cleaning solution.  

A similar product to the Fisher Versa-Clean is Liquinox, https://alconox.com/liquinox but it is likely more concentrated since it only requires 100:1, and at that concentration it will achieve a low surface tension of 29, but it is anionic and will foam.

R/Neil