Investigating if ultrasound is harming LPs


Take a piece of a LP and US clean it.

With a precision weight scale. Taking the weight before and after the ultrasound cleaning. To determine IF any material is removed from the LP or not with the ultrasound usage.



The things that are needed for the test setup:

  • US DIY 6L cleaner. With 180 watt at 40 kHz.
  • Weight scale 2 decimals of a gram and max 5g capacity.
  • A piece of a real LP record 



First I selected a LP and tried to cut out a piece that is as close to 5 grams. To get the maximum size as possible that the scale can support. Tried to get a piece that includes lead-in to lead-out. To especially get some of the "glossy" part of those.


I used the US cleaning to do an initial cleaning of the record ~5g piece.


When I was not interested in weight loss due to dirt coming off. I need to start with a clean piece that is just the LP material and nothing else. When the goal is to determine if the ultrasound is removing any material or not. 


For the US bath I used a little bit of heat 30°C and reverse osmosis RO water (more or less the same as distilled water). And some wetting agent.

When we want the scrubbing bubbles being able to work into the groove. The piece of the LP will hang in the water like a record is and not lay down in the bottom of the US bath tub. 


I will run the US machine timer set to 30 min. That in practice a LP is less than half of its area at any time in the bath. That means more than half of the LP area is not in the bath when the record is revolving during a normal cleaning session. So in practice by having this piece submerged and US cleaned effectively for 30 min is like someone is spinning and cleaning in the US bath for more than one hour ! So it is more correct to see this 30 min as over an hour of US cleaning if it were a whole spinning LP. 


For the weight scale I make sure that the LP piece is clean and dry. And I try several times to rule out deviation between measurements, if any. Method where I learned to put the piece of LP on the exact same place on the scale plus I for each measurement looked that it went back to 0.00 g when I picked up the piece. I also reseted by pressing tare and looking again so I got 0.00 before putting the piece on the scale to get a new reading. 


Calculation example if we have a 5 g piece and 1% of its material were removed. Then that 1% should weight 0.05 grams and 0.5% should be 0.025 gram. That is what I see no issues to detect on the weight scale when the repetition accuracy is greater than 0.025!


So this method should be able to detect if less than 0.5% of the LP were removed by the scrubbing bubbles by the ultrasound and it's usage of it. 

But I was not expecting what happened below..


1st try Results

The start weight of the cleaned LP piece:

  1. 5.01 gram
  2. 5.01 gram
  3. 5.01 gram
  4. 5.01 gram
  5. 5.00 gram
  6. 5.00 gram
  7. 5.01 gram
  8. 5.01 gram

Average: 5.0075 grams.


After US bath "cleaning" first weight session:

  1. 5.02 gram
  2. 5.02 gram
  3. 5.02 gram
  4. 5.01 gram
  5. 5.01 gram
  6. 5.01 gram
  7. 5.01 gram
  8. 5.01 gram

Average: 5.01375 grams.


Hmm here is something fishy business going on between the weight sessions..


After the first US bath "cleaning" second weight session:

  1. 5.02 gram
  2. 5.02 gram
  3. 5.02 gram
  4. 5.02 gram
  5. 5.02 gram
  6. 5.02 gram
  7. 5.02 gram
  8. 5.02 gram

Average: 5.02 grams.


So there is something going on between weighting sessions..

I have taken those two weighting sessions and the average of the 2 x 8 measurements is 5.016875 grams.


Second try cleaning 

Now I am repeating the 30 min (one hour see above) Ultrasound treatment/"cleaning" for a second time.


And will weigh it also in two sessions and see what we get.

After 2nd US bath "cleaning" first weight session:

  1. 5.02 gram
  2. 5.02 gram
  3. 5.02 gram
  4. 5.02 gram
  5. 5.01 gram
  6. 5.01 gram
  7. 5.01 gram
  8. 5.01 gram

Average: 5.015 gram


After 2nd US bath "cleaning" second weight session:

  1. 5.01 gram
  2. 5.01 gram
  3. 5.01 gram
  4. 5.01 gram
  5. 5.01 gram
  6. 5.01 gram
  7. 5.00 gram
  8. 5.01 gram

Average: 5.00875 gram


So after a second US cleaning round and having the 16 measurements from the first US cleaning round.

Average from the two measurement sessions is after the 2nd US "cleaning": 5.011875 grams.



Is that there might be some deviation between measurement sessions of some reason that I can't explain:

  • Maybe it would average out if I took more than 8 measurements.
  • I should take more than only 8 measurements before the first UC cleaning session, which is why I later doubled them.
  • And I felt that I got better and better in my measurements routine. So the later measurements are more stable and have higher repetition accuracy than the first ones had.

I could leave the first iteration out from this post, but I wanted you all to see the whole process and not manipulate the findings.


Of the conclusions above I feel and believe mathematically with more samples that the second round is the one to look at and dismiss the first round.


Before I did the second US "cleaning" the average weight of the 16 measurements were:

  • 5.016875

After the second US "cleaning" the average weight of those 16 measurements were:

  • 5.011875

5.011875/5.016875 = 0.999003363647


Almost 0.1% (0.0996636352%) less weight after the second US cleaning.


That can be one of two things or little bit of both also:

  1. Measurement deviation before and after measurements. And more repetitions and measurements could be done. But I will stop here.
  2. That actually a VERY tiny part is removed of the LP by US


It is up to you guys to decide what you believe the data means. 


But remember it is a rather powerful US with 180W and in practice a very long US cleaning session as explained above.


Another note in the method of what I observed was that the little LP part were moving around in the bath when it were only hanging in a string. Usually a record is more firm and stable when the scrubbing bubbles are acting on its surface. If that makes any difference for the outcome but worthy of a note.

​​​​​(I got images on all the things and measurements 40 (!) But this forum is making it hard for me to attach them here)



My guess, like someone above mentioned, is that the record is slightly hygroscopic and the very long soak for your test is different from your initial cleaning.  Try also soaking the pre test sample in water for the same period and weight the sample before subjecting it to the ultra sound cleaning.  That will at least reduce that potential variable.  

@larryi thanks for the input:

My guess, like someone above mentioned, is that the record is slightly hygroscopic

I thought I provided several different reasons why it can't be hygroscopic in my previous post.

But we will go the extra mile here and try to debunking that myth, I took the out the part and the scale again. And I were thinking that after 24 hours drying time it should have got dryer. I got 5.02 grams again. So not there is nothing that has evaporated the last 24h. 👍

I think you are pushing the accuracy of the scale and the amount of change beyond a reasonable level. The ambient temperature, relative humidity, and atmospheric pressure will all be an affect at the precision you are attempting. They should all be a part of the reading at each step of the experiment. The drying time (as you said) will also affect the reading, So to continue your experiment... Try your 8 measurements at 1 hour, 4 hours, 12 hours, and 24 hours to try to narrow done the ambient variations that occur and stabilization of the vinyl after US cleaning.

I really think the better test would be the frequency test of before and after as lewm said.

Scales are LEAST accurate at the extreme ends of their range. In this case 5g and 0grams. You are better off using a piece of vinyl coming in about 2,5grams. Also unless you are using a Mettler scientific laboratory scale in a temperature controlled environment, your accuracy at the .00X level is not going to be good. Interesting experiment though.

added weight could be remaining moisture? Or a coating of surfactant?