@oldaudiophile,
As I think I may have mentioned earlier, most of my core collection of LP records are already relatively clean. Should I avoid using the Knosti & Liquinox pre-clean step for those, altogether, or does that matter at all? I don't mind doing this pre-clean step at all, unless it might be detrimental or superfluous. I do have some very old records I inherited from my folks when they passed (e.g. 33's and 78s of Sinatra, Como, Mario Lanza, etc.). Maybe the Knosti pre-clean step should be relegated to those?
If your records are reasonably clean, meaning they are visibly clean - yes you can skip the pre-clean with Liquinox. But doing the pre-clean step is not going to harm.
Now a big caveat, everything I have been discussing is for vinyl records, not lacquer/shellac which are very different, and I have very limited knowledge. What little I known is here is the Library of Congress procedure: Cleaning Lacquer Discs — NEDCC. Cleaning lacquer/shellac records is not something I have dived into. But I am confident that Tergitol 15-S-9 can be safely substituted for Tergitol 15-S-7. In 2007, sd_bp_07.pdf (indiana.edu) recommended: Lacquer (nitrocellulose laminate) discs are cleaned using a solution that is 0.25 parts Tergitol 15-S-3, 0.25 parts Tergitol 15-S-9, 98.5 parts deionized water, and 1-part clear ammonia.
The blend Tergitol 15-S-3 (which is insoluble in water) & Tergitol 15-S-9 (which is soluble in water) are the constituents of the commercial product Tergikleen. I am not a fan of Tergikleen (which my book discusses in Chapter IX) because of the insoluble Tergitol 15-S-3 ingredient.
But let me call your attention to these 'details' from the paper/book sd_bp_07.pdf (indiana.edu):
-The advantage of the ammonia is that it minimizes the amount of mechanical scrubbing required to remove palmitic acid as well as minimizes the amount of exposure of the laminate to water, as water can cause the laminate to swell and delaminate.
-Discs with a compromised lacquer layer (i.e. cracks or signs of delamination) should not be cleaned with an aqueous solution as this will accelerate delamination.
-Lacquer discs receive a final rinse with a solution that is 99.75 parts deionized water and 0.25 parts Disc Doctor solution. The Disc Doctor solution is used to lower the surface tension, allowing water to push down into the grooves for more thorough rinsing. I would avoid this practice. Not knowing what is in Disc Doctor solution this is not smart. You could just add 0.003% Tergitol 15-S-9 (this is less than 1-drop/Liter-DIW) and get the same reduced surface tension results with little risk of residue.
Beyond what I have addressed above, which would apply to manual cleaning with a label protector that is pretty much the extent of my knowledge. However, for manual cleaning with a label protector I would recommend using Tergitol 15-S-9 at only 0.1% instead of 0.5% which is way more than necessary. Additionally, I would recommend the Record Doctor brush with initial tap water and then DIW spray like the book says. For use with a vacuum-RCM, I would avoid the 1% ammonia and just use Tergitol 15-S-9 at 0.05% (as specified in the book) to avoid any corrosion of the vacuum-RCM and ease of rinse. Records that showed need for the 1% ammonia (+Tergitol 15-S-9) would best be cleaned manually with the label protector. I would recommend for the Groovemaster, the modifications I address on page 33 of the book for ease of use.
Otherwise, I would need to research in much greater detail to provide any additional guidance. Lacquer/shellac records used a variety of fillers and how each may respond to any kind of cleaning process that exposes the edge to extended periods of immersion (such as UT) would need to be considered and inspection procedures developed to allow segregating those at risk of delamination. There hopefully would be info available that differentiates the filler used by each pressing plant/label. If UT was to even be a consideration, it would need to be 80-kHz or above, at low power (the variable power of the Elmasomic P-series would be best) and probably near room temperature (a pump/radiator could control the temperature). But I am no longer retired, and I do not have the time to do a deep dive into cleaning lacquer/shellac records to where I would be confident in my recommendations.
By "and then secure the heaters", do you mean heat the tank water to 26C and then shut off the heat for US cleaning, as the US activity heats the tank water anyway?
Yes.
...it, seems to indicate that a 20-minute total US cleaning cycle in the Elma Sonic P60H would be safe. Do I understand that correctly?
20-min is safe at a spin speed of 0.5-rpm and at a max temperature not to exceed 100F. For reference based on a user experience, 20-min at a spin speed of 0.15 rpm reaching a temperature of 122F is not safe.
Should 20-minute cleaning cycles be reserved for very dirty records or does that matter?
That depends on how clean the record is to start and how many records you are cleaning - is it 1, 2, or 3. The dirtier the record and/or the more records you clean at-once, the higher the bath load, the longer the duration. I the records are dirty, cleaning 3 at a time is not recommended. But at this point, I stop making any definitive recommendation, and let you do your own experimentation to develop your own process.
Good Luck
Neil
