Investigating if ultrasound is harming LPs


Description

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.

 

Material 

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 

 

Method

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.

 

Conclusion

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)

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optimize

I actually studied the effect of ultrasonic cleaning of LPs in great detail back in the late 70s when I built my first ultrasonic cleaner. I used a combination of optical microscopy (Olympus Laboratory Microscope at about 10,000X) and Photoelectron Spectroscopy (HP 5950A Spectrometer) to analyze sacrificial test LP samples before and after various cleaning procedures. Photoelectron Spectroscopy is sensitive to the top 5 nanometers of the LP surface and can determine the chemical structure of the LP surface and the chemical composition of contaminants on the LP surface. These experiments were done on sacrificial records that had obvious contamination. All of these experiments were done in a clean room environment.

Regarding US cleaning time, my experiments demonstrated that longer than a few minutes in the ultrasonic bath had little beneficial effect on the overall cleaning process and the possibility of a detrimental effect. Most of the cleaning took place in the first few minutes in the bath. I did observe that extended time in the bath would leach plasticizers, stabilizers or other additives from the bulk of the LP and eventually pit the LP surface. Once the plasticizers or stabilizers are fully depleted, the LP surface would become brittle and micro-cracks start to form. So I tried to keep the time in the bath to a minimum. When I finally set up my ultrasonic cleaner, I typically had it set at about 2 RPM and a run time of about 6 to 9 mins. That corresponds to actual exposure times of ~ 2 to 3 minutes (~1/3 of the LP surface is in the bath at a given time). For my setup, between 1 to 3 RPM worked fine. The 6 min time was for my LPs purchased new which had no obvious contamination and the 9 min time was for previously owned LPs. An LP that was quite dirty might occasionally require some extra time. I used this ultrasonic cleaner for over 30 years with excellent results and never any issues with my LPs. Even new LPs exhibited a significant improvement in SQ after US cleaning. Typically once an LP is US cleaned, it will need no further US cleaning if handled properly.

Besides time in the US bath, the key to optimum US cleaning is the proper bath solution and choice of surfactant. The most common bath solution is distilled water or distilled water with a small percentage of isopropyl alcohol. There are many surfactants to choose from. Typically nonionic surfactants are preferred. For my US cleaner, I used an alcohol ethoxylate with the general structure R(OCH2CH2)nOH where R is the alkyl chain and (OCH2CH2)n is the ethylene oxide (EO) chain. I chose the lowest molecular weight that would be soluble in water at room temperature. For solubility in water at room temperature, alcohol ethoxylates should have an average alkyl (R) chain length of 12 C atoms or more and contain at least 5 ethylene oxide (EO) units. The lower molecular weight surfactants were less likely to leave residue on the LP surface and were easier to remove with a distilled water rinse after the US bath.

For reference, the alcohol ethoxylate I used is similar in structure to Tergitol which is a secondary alcohol ethoxylate. Triton-X 100 is an octylphenol ethoxylate which in this case contains a phenyl group as part of the hydrophobic tail.

The concentration of the surfactant is also critical for proper cleaning. It is important for optimum cleaning to have the surfactant concentration at or above the Critical Micelle Concentration (CMC) and the cleaning bath at the proper temperature for micelle formation. The CMC and bath temperature are surfactant dependent. A micelle is an aggregate of surfactant molecules in a liquid solution with their hydrophobic ends on the inside of the aggregate and their hydrophilic ends on the outside, so that hydrophobic residues can be emulsified inside these aggregates. Micelles only form when the concentration of surfactant is greater than the CMC, and the temperature of the system is sufficient for micelle formation. The importance of micelle formation is that the micelles can emulsify surface contaminants that would otherwise be insoluble in the cleaning bath. This allows for the hydrophobic contaminants to be removed from the surface. For my nonionic surfactant the ideal bath temperature for CMC formation was between 36 to 38 degrees C.

 

Pindac, If you can bear to read all the posts on this thread (and I don't blame you if you cannot bear it), I invite you to look for mine back up near the beginning, where I suggested that one proper way to make the assessment is to use test LPs with specific pure tones encoded on them or it, say 100Hz, 1000Hz, 10kHz (all 3 frequencies on the same surface of the same test LP).  Since we would expect HF to be affected by excessive US cleaning, ahead of any effect on lower frequencies, you could play the test LP tones into a storage oscilloscope, to measure both amplitude and accuracy of the frequencies produced, before vs after cleaning, using same cartridge, tonearm, TT..  Yes, this is an oversimplified desription of the experiment I would endorse; I do realize that the US parameters, perhaps the buffer, the temperature, and many other factors could affect the results, and proper controls would be needed.  But basically, any eroding of the signal voltage amplitude or alteration of frequency of the 10kHz band in comparison to the 100Hz or 1kHz bands encoded on the very same LP would be meaningful to the degree that the lower frequency bands would have been exposed to the exact same conditions as the HF bands on that test LP.

Your questionable scientific method aside, the proof is really in the pudding.  I've been using ultrasound for many, many years now (was an early convert to Audiodesk).  I always clean my LPs before playing.   On Sunday mornings, I almost always listen to one of the MFSL first Beatles albums.  I'd say "Help" and "Rubber Soul" have been ultrasonically washed well over 200 times (probably more).  And they still sound perfect.

In fact, writing this post had whet my appetite for Rubber Soul.  Later. all....

@lewm, The experiment you suggest is interesting but as I have observed and others every LP that I have cleaned with an US cleaner sounds better after cleaning. The majority of my LPs were purchased new and US cleaning improved the SQ on all of them. In some cases a slight improvement and in others a significant improvement. Primarily reduced background noise and elimination of clicks and pops, and improved detail and clarity. 

As i stated in mp post above, US cleaning only requires a couple of minutes of actual exposure and in that time frame I never observed any measurable degradation of the LP surface. Certainly degradation of the LP can occur with long US exposure. 

Then there is me, who doesn't even own a US RCM and does not even care if US can damage an LP.  But for the umpteenth time, the question put forth by the OP was about a METHOD to determine whether US RCMs can damage an LP.  Not per se whether US does in fact damage an LP.