@terry9:
This is going to be a long thread, but the devil is in details.
The fundamental challenge with cleaning records, is that we are trying to achieve a cleanliness level better than what we can see. Right now, the record UT vendors are using post cleaning microscopic inspection to determine the process parameters. For critical application precision cleaning cleanliness is defined by two parameters - non-volatile residue (NVR) which relates to oils/grease and the like, and particles. For cleanliness levels that are below visible, very high purity fluids are used to flush for final clean/verification of the surface to determine residual NVR that an be determined by a number of different methods sensitive down to about 1 mg/ft^2, and for particulate cleanliness. A particle count is used and measurements to 1 micron are common. Unfortunately, none of this is practical ($$$$$) for a record. Additionally, the groove design and that fact that the stylus does contact the entire groove surface makes it difficult to determine what is the minimum cleanliness level required, some particulate may be inconsequential depending where it is.
But, your process of reviewing post cleaning effluent is often used. You establish minimum process requirements such as chemistry, equipment, temperature and time and then observe the effluent at the end to determine if the process has removed all the contaminants it can. Although the eye cannot see individual particles much less than 50 microns, in clear water, very small particulate can often be detected as a bloom/turbidity - very small particles act as colloidal suspensions and can conglomerate into larger particles that can then be detected.
When you try to make the process cost effective, a whole other level of challenge arises. If you are going to push the bath chemistry, it has to be the right chemistry that will suspend the contaminants to prevent redisposition with enough concentration to get repeatable cleaning performance - the last records in the bath are cleaned as well as the first, and the first records are rinsed or cleaner just as well as the last.
In another post on UT tank cleaning, I wrote something similar to the following, that I have slightly modified by adding a cleanliness verification step:
If you are using UT to clean a lot of record, consider using a demineralizer, and this is the best value I have found,
https://dirinse.com/product/d-i-rinse-pro-50-unit/. If your tap water is of reasonable quality, it can produce about 2000 gallons of demineralizer water at a cost of $0.20/gallon, and it can be refilled ($200 for 2 refills), and the valve arrangement can make a very coinvent install. If you have a source of readily available cheap DI water, then you don't need to worry about bath life or filters/pumps etc to extend the bath life. And, you could easily add an effective rinse/cleanliness verification step as follow:
Step 1. Clean records in UT tank with aqueous chemistry. You do not need to use a lot of cleaner since you will only be using one tank-bath for each batch of record. This way you can baseline that every record batch will be exposed to the exact same chemistry.
Step 2. Drain UT tank to household waste drain. While draining use just warm tap-water to flush over records for first rinse. This will remove most cleaner residue and loosen contamination.
Step 3. Refill UT tank with only DI water and using ultrasonic, perform rinse/final clean to remove mostly any remaining very fine particulate. Hopefully the chemistry in Step 1 removes all surface oils and greases that may trap/cover fine particulate, so that only DI water is required to do the final polish.
If you want to do a cleanliness verification - at the conclusion of Step 3, obtain about a 100 mL sample of the UT DI water in a clean clear container. Cap, shake and verify no stable bubbles - this will verify the cleaner has been removed. To check for particulate, place a piece of white paper behind the container and inspect for visible particulate or turbidity. You should not see any visible particulate and unless very turbid (and this will take some experience), at this point the process has done all it can do. If the sample is very turbid, reclean. Note - if you are constantly having to reclean, then Step 1 needs to be adjusted - it may be the chemistry, the chemistry concentration, the bath temperature, exposure time, record loading, or the tank Hz and watts. But an occasional (not frequent) reclean is generally indicative of a pretty efficient process. If you never have to reclean, chances are you doing more than 'required', but that is not necessarily bad.
Step 4. Remove records to dry.; or if cleaning records again proceed to Step 5.
Step 5. If cleaning another batch of records, or cleaning the same records again, just add cleaner to the existing DI bath and begin at Step 1. This reduces the amount of DI water used.
Quick analysis with a 1.5 gal UT tank volume. The demineralizer should provide enough for 1333 tanks, and assuming you are cleaning 3 records/batch, that is 4000 records. The initial cost is $0.30/tank for DI water, and for the Tergitol 15-S-9 at 6 ml/tank, is ~$0.28/tank for at total of $0.58/tank or about $0.20/record. After the first 1333 records, the DI water cost drops to $0.07/tank, so the total per tank cost drops to $0.35/tank, and the per record cost drops to ~$0.12/record based on the assumptions of this analysis. Clean 6 records per batch, and the per record cost adjusts proportionally, down to as low as ~0.06/record.
This is just a quick analysis. Like I said, you are still in the experimentation phase. Good Luck
R/Neil
