Investigating if ultrasound is harming LPs

@antinn  Agreed. I misunderstood you to be recommending frequencies below 60kHz, whereas in fact you are warning against high power at low frequency. I read it wrong.

@terry9 ,

No, I did mean to say <60kHz.  Here are the basic UT rules:

1.  Power needed to produce cavitation is inversely proportional to kHz.  So, lower kHz requires less power to produce cavitation.

2. Cavitation bubble size is inversely proportional to kHz.  So, lower kHz produces a larger diameter bubble.

3. Cavitation intensity is proportional to the bubble size and the power into the tank.

Ergo, a lower kHz UT with a lot of power can produce very high cavitation intensity.

Take care,

@antinn  Do you really mean, 'less than 60KHz', or should that read,  "greater than 60 KHz?'

Thanks!

Ijgerens, I didn’t get to see your first post until after I wrote mine. I thought it was excellent.

@iopscrl 

I agree with your findings regarding US cleaning. I believe that your actual time for your LPs exposed to the bath is ~5 min. Typically the bath solution is below the LP label so only about 1/3 of the LP is in the bath at any given time. So 15 min of run time equates to ~5 min of exposure which is a reasonable cleaning time. 

A controversial subject for which no one has produced conclusive evidence to support or refute the question.

MY EXPERIENCE is that US cleaning does not degrade an LP.  Again, MY EXPERIENCE, is that that US cleaned LPs sound dramatically better after a full US cleaning cycle.

My process:  Spin Clean, rinse, US bath using "Rushton's formula", rinse, Nitty Gritty vac dry.    US cleaning cycle at about 30' C / 15 min @ 0.33 RPM.  Each LP receives 5 full rotations with only half the LP submerged at any one time...so the entire LP is exposed to US bath for about 7.5min.

My results are dramatically quieter background.  I now have 50-60yr old LPs with a noise floor as low as my system, and lower in some cases.  I can easily hear a master tape trail off to the background, or an abrupt cut off at a very low level.  I hear greater HF extension, and much greater clarity around micro details- air, space, harmonic extension.  Transient response is much improved, with the leading edges of a transient much more audible.  My thought is that a micro layer of dirt and debris becomes bonded to the groove walls.  This layer essentially blunts the extreme edges of the very small groove modulations and masks/obscures all of the microdetails that were originally captured.  Standard light abrasive cleaning (spin clean, nitty gritty, VPI etc) is insufficient to remove this layer.  US cleaning is able to break down and remove whatever compound this layer is made from, and uncover the original grooves.

If US cleaning is in fact detrimental than shouldn't we hear degradation rather than improvement ?

So called Golden Ear reviewers have not heard detrimental changes, so far.

Instead of measuring LP weight, we should measure what we actually hear.  If someone is interested in conducting a test, I would suggest:

Purchasing a LP test record with HF tracks containing measurable content to at least 20khz.  Make 3+ rips/captures of the tracks at a min resolution of 24/192 and closely examine the wave patterns and FR extension above 15khz.  Wait 30-60min between each play of the LP tracks. (there is some evidence that repeatedly playing the same tracks at short intervals can be detrimental).

Then US clean.

Then capture/rip again at least 3 times, and compare the resulting wave patterns and FR extension above 15 khz.

If possible, overlay the graphs and publish the results.

Variable- how likely is it that the grooves containing the desired content can deteriorate from routine playing using a carefully aligned cartridge ?  Would ambient temperature and humidity affect the test ?

Report back to the group.

Ok, maybe I should have been more detailed regarding the experiments I did back in the day to determine if US cleaning would cause damage to LPs. I certainly was concerned with this and why I did the experiments on sacrificial LPs before I actually used an US claener on my good LPs.

I used an Olympus Optical Microscope (10,000x) and Photoelectron Spectroscopy to analyze sacrificial LPs before and after US cleaning.

For up to a 5 min total US exposure, optical microscopy did not detect any damage but did observe complete removal of large scale contaminants. Photoelectron spectroscopy found the LP surface to be fairly clean with a minimum amount of contamination.

Between 6 to 10 min total US exposure, optical microscopy did not detect any damage and no remaining large scale contaminants. Photoelectron spectroscopy detected the presence of plasticizers, stabilizers and other additives that have been leached from the bulk of the LP.

Between 11 to 15 min total US exposure, optical microscopy could detect some pits and micro cracks beginning to form. Photoelectron spectroscopy detected large amounts of plasticizers, stabilizers and other additives that have been leached from the bulk of the LP.

So at greater than 10 min total US exposure we are beginning to detect damage to the LP surface and significant leaching of plastizers, stabilizers and other additives from the bulk of the LP.

Whether any of this affects the SQ of an LP, I can’t say because I would never leave any of my good LPs in an US cleaner that long.

Results may vary with different US cleaners and different LP formulations.

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. 

@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. 

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....

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.

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.

"The ’science’ of listening will always be flawed. "

Science is inherently flawed, imperfect, and incomplete that is the way that the world works you can not proclaim one aspect of science more important or more truthful, valid, or meaningful than any other aspect of science. One thing we have learned is that the sciences are all connected and the division, separation, and distinction we have made between the sciences are man-made and deceptive because we don’t/can’t see the whole picture but of course some will insist they have ascended the mountain and seen the truth that has been concealed from the ignorant, the poor, and my favorite "the uneducated".

mahler123

How many times does one clean a given record this way?  I thought ultrasound was used once, and after only again if something catastrophic happened, like if the lp was buried in a mudslide in Turkey ...

I have found that one cleaning usually suffices. However, I have a handful of favorite LPs that I've cleaned a second time. That's because - no matter what some may claim - an LP will acquire some dust during play. (There is no way to prevent that in a home environment. Even the use of a conductive sweep arm on a turntable can only collect dust from the tiny patch beneath it, leaving all he rest of the LP surface exposed.)

My gut feeling is the improvement made by deep blasting 50 years of crap out of the grooves would more than offset a loss of mass in the tenth decimal place ...

I'll go one step further. Even brand new LPs have dust and contaminants on them from the manufacturing and packaging process and they, too, benefit from cleaning.

Many audiophiles have never heard a truly clean record. You're one of them if you're routinely seeing dust on your stylus.

How many times does one clean a given record this way?  I thought ultrasound was used once, and after only again if something catastrophic happened, like if the lp was buried in a mudslide in Turkey.  My gut feeling is the improvement made by deep blasting 50 years of crap out of the grooves would more than offset a loss of mass in the tenth decimal place, but what do I know?

Hypothetical: If there was evidence a UT Cleaning was a cause of a loss of recorded data, as a result of effecting the Modulation in the Groove.

Would not a Test LP be a better to use as a LP Sample, as a Few Samples could be acquired and used in a manner that could at some point enable for differences developing between the LP's to be distinguished. 

Say a particular Khz, Rotational Speed and Temperature were discovered to have detrimental effect, as a result of Comparisons of the Test LP's, would this then be one of the cleaning environments to be avoided.

Is there not a Computer Software today such as 'Analogmagik', that would help with substantiation of  differences being detected between the Test LP's, if something is also being suggested there is a audible difference occurring.

For the Record, I abandoned the UT Cleaning and use the PAVCR Manual Cleaning Method, with solutions available to be produced in the UK. This has proved most satisfactory and Purified LP's are certainly a end product.

I commend your effort to try the experiment.  Given the tiny scale of weight we are interested in, I think this experiment is impossible to do reliably without very expensive lab equipment and carefully conducted in a controlled lab environment...

I believe both Rega and Ortofon do not believe in cleaning records with any kind of solvent or liquid. Dry cleaning or surface dust removal is ok, same for stylus cleaning. I personally use the record DR as well as manually cleaning with vinyl revival product. Generally though, I just dry clean them with a record brush. If you think about it, adding a liquid could just be causing mud/sludge, which may or may not be fully removed. Maybe best to let alone and dry brush and enjoy the music. I gauge it by examining the stylus upon completion of play. If it is consistently gunked up with crud from a certain record, then I proceed to use liquid(s). A lot of the time, the stylus appears rather clean, even after playing a thrift store find. It just depends on the record. My ears are old, and I honestly cannot hear most of the surface noise present most of the time, maybe it’s s good thing!😁

Honestly, each time you play a record, there is some minute amount of material being removed...how can there not be? A hard diamond running through the grooves (softer material) creating friction and of course heat. It is inevitable degradation.....with thousands of records, I doubt I’ll wear any of them out during the rest of my time. I own so many now that I honestly Forget what I have! Not a bad problem really....wifey thinks otherwise...🤨. Now to sneak the new Accuphase into the house...🙄

@cleeds     I think more Captain Subjective.  The 'science' of listening will always be flawed.  Listening is always subjective and the results never scientific unless conducted under scientific conditions.  OP is to be praised for trying to build an objective scientific examination.  Brave, very rarely seen here.  If you can't follow that, then just dream on.......................................................................................................................and on.......................and.....................zzzzzzz

The damage to the record can alter its physical dimensions or its physical properties.  Damage to the physical dimensions - any dimension change to the groove which can include change to the side wall modulations, or the material surface roughness 'may' be audible depending on the reproduction playback equipment (starting with the stylus shape), the listening environment and finally the listener.

Damage to the physical properties is much more insidious.  This can alter the durability of the record.  This damage becomes cumulative and if the degradation is graceful the listener may not notice unless they periodically compare the record to a control.  

UT is a high energy process and while there is no evidence that the record is heating on any bulk scale, that does not exclude what may be happening at the surface boundary as its bombarded with high energy implosions.  Heat is the main enemy of records.  If they overheat (beginning about 50-55C) PVC releases hydrogen chloride gas which if not scavenged by the internal stabilizer (part of the composition) the surface embrittles.  Once pressed, the record only has very limited stabilizer left.  Once its exhausted, that's it, any further excessive heating and its record damage.

So, because of uncertainty, being 'reasonably' conservative by keeping temps <40C, not spinning too slow (<~0.3 rpm), not using aggressive chemistry, not exposing for extended periods (>~20min); and at <60 kHz no crazy high power, there should be reason to suspect that UT is damaging the record.   But get on the wrong side of being conservative and UT can damage that record.  But trying to determine absolute thresholds of when and what damage will occur would be a serious scientific endeavor.  Although Olympus has some serious digital microscopes (magnification >15,000X) - check out the LEXT™ OLS5100 3D laser microscope that precisely measures shape and surface roughness at the 
submicron level.  But you can only measure a very, very small area, but probably better than scanning electron microscopes.

Just some casual thoughts.

Note very clear thinking, @clearthinker . You manage to mischaracterize my point and misquote me, all in only three lines.

lewm

Cleeds, if you want to know whether your US RCM can damage your LPs, then you have to design an experiment to answer THAT question on the physical level.

I shared my listening experience and have conducted experiments to my satisfaction. Please feel free to conduct your own tests. Also please kindly note what I wrote in the post directly above yours:

If science is the goal, listening is necessary to correlate the results with the measurements.

Cleeds, if you want to know whether your US RCM can damage your LPs, then you have to design an experiment to answer THAT question on the physical level. If you want to know whether you can hear a problem, then just listen. Aural memory is so poor that you’re likely to hear what you want to hear. OK with me but just be aware of the bias issue.

clearthinker

At last an attempt at science on AG.  Congratulations. But most AGers would prefer to clean the LP, listen to it and see if they can tell any difference.

The notion that listening is itself unscientific and is an obstacle to science is misguided. If science is the goal, listening is necessary to correlate the results with the measurements. This is such a fundamental premise that I feel like Captain Obvious for mentioning it.

At last an attempt at science on AG.  Congratulations.

But most AGers would prefer to clean the LP, listen to it and see if they can tell any difference.  You can read them above: 'if it's not detected by a listening test then there's no damage'. etc etc etc

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

Considerably less than I expected.

Almost nothing.

@antinn Points taken. Elmasonic commercial unit (and now that reminds me, 37KHz, not 40, 37 being even more energetic), VersaClean lab detergent from Fisher Scientific, air dry in a clean environment. Control was the other half of the record.

Thanks for weighing in @antinn . Always good to hear from you and always good to hear from an international expert. 

No objection to any of your finer points.  But you posit all good reasons why the weigh method is not the right approach, on which we agree.

@terry9 & @lewm,

This is such a can of worms.  There are so many variables involved such as the record itself, of which we do not know the actual composition, but you may segregate to virgin and recycled, clear, black and colored.  But this would not cover the older composition that may have anti-static ingredients that may be exhausted from extended UT exposure.

Then you need to establish control for the ultrasonic tank.  If it's an inexpensive tank, can you believe the 'published' frequency and power; and other aspects such as power/volume and sweep frequency. Then you have rotating speed and of course duration and temperature.

Then you have the process chemistry - what exactly has been added - actual chemical and concentration.  To make it easier - just start with lab grade high purity to reduce the variability.  And the 800-lb Gorilla is how to dry.  The 'dry' surface will be influenced by the background environment.   

But, after all is said and done, what damage do you expect?  Assuming you eliminate water/solution residue as a variable, it should come down to damage of the thin high frequency side wall ridges or general surface erosion.  Damage to the side-wall ridges should result in loss of high frequency data.  But the damage may not be acute, but more chronic.  So, the damage does not become evident until after multiple plays.  Surface erosion may have no damage to frequency output, but it could increase the surface roughness which would then raise the background noise level.  But measurable weight loss is unlikely.  You could try sampling post cleaning the water for particle count, but you need to be able to differentiate record plastic from tank metal, possible but quite scientific.  So, @lewn is right that one of the best ways is to compare digital files before and after since hearing is so subjective.  

However, the 800-lb elephant is that unless the 'control' record is very clean, UT may alter the output but beneficially.  So, you need to first establish initial cleanliness w/o using UT?.  Too many pressing plants are very dirty with atmospheric contaminants including condensing organics from the lubricants used by the pressing equipment - all those moving parts are generally lubricated.

However, can UT damage a record, yes.  I am working with someone right now who was cleaning 25-min with a very powerful unit, very slow rotation and allowing the temperature to reach about 55C.  Chemical reaction rates generally double for each 10C temp increase, and cavitation intensity for lower kHz can also increase.  One recent late 1960's record finished with a mottled dull finish surface.  He said it still sounded OK.  He is now installing a cooler and increasing the rotation speed.

Just some casual thoughts.  

@lewm Agree, not exhaustive. There are many formulations of vinyl, for one thing. But then, cooking one side for an hour, reaching high temperatures, is a torture test by any standards - compare a with normal procedure of 6 rotations per hour, which leaves each small portion submerged for at most 4 minutes. Compare 60 minutes at temperatures exceeding 60 C. Frequency was 40 KHz, which is common and the most damaging to records.

Not publishable, perhaps - the only unscientific thing about the test was my generalizing to all vinyl records and all US frequencies. The human ear is a good transducer and it correlates well with other human ears, which measurements may not.

How about a before and after scanning electron microscopy image?  View the “damage”?

I've been using the Klaudio ultrasonic cleaner for years without any issue at all. The difference a truly clean LP can make can be astounding.

At my age it was taking too long to read the entire thing but I guess it is ok to keep using my ultrasonic cleaner. Most record only need one cleaning. The US machine was the best investment I have made for enjoying vinyl.

How bad can the damage be? Good question. But I thought the question was how to detect damage, not whether it’s bad (or noticeable) or not. Whether it's noticeable in your test of course would be a function of the listener’s acuity as well as the degree of any damage. Besides, I did not say that I know the damage could not be detected by a listening test; you said that you could not detect damage based on apparently one experiment with one LP using one machine under conditions that you typically use for cleaning (I am guessing). I think you would admit that your study was not exhaustive.  In my opinion, to address the issue you'd want to do it scientifically to get an objective result, not a subjective one.

@lewm  " And you cannot even hope to detect such damage with a listening test, as someone else seems to claim. "

If it can't be detected by a listening test, then just how bad can the damage be?

@larsman yes I agree.  Can’t handle record noise anymore now that we are well into the digital age.  I just got an ultrasonic cleaner and finally I can stand to listen to records more once again. 

I ultrasonic each vinyl once, or twice for old used ones as needed, then place it in an inner plastic sleeve and the album cover is then put into an outer plastic sleeve with the sleeve opening in the BACK of the album. Hence zero further dust accumulation. Point being, with one or two ultrasonic wash, no way I have to concern myself over ultrasonic cleaning damage.

My records sound better after a session in my DeGritter than they did before. Surface noise much reduced. That's all I care about... 

It’s true that dirt and grime on a record results in less treble and detail and adds noise resulting in a “warmer” sound ie relatively more midrange. Take away all that mess and vinyl starts sounding more like digital and vice versa. If you want warmth, better off pursuing it with the appropriate amplification known for that.  You can have more warmth with everything that way including with impeccable  digital sources. 

Like I said above, but which gleaned no attention at all, if you want to find out whether US cleaning can damage the encoded music signal on an LP, the way to go is to look directly at the signal on an LP before vs after US cleaning, not the weight of the LP before vs after cleaning. With respect for your diligence, it is misguided, because your method is faulty to begin with. Which is to say that if you conclusively find no difference in weight, it does not mean necessarily that no damage was done to the music signal. And you cannot even hope to detect such damage with a listening test, as someone else seems to claim. You need the proper electronic tools and the capacity to collect the data for comparison (e.g., an oscilloscope with storage function, a test LP with pure tones recorded on it in stereo, and probably other devices I have not thought of).

You've discovered the methodology for removing the warmth from vinyl.

I ultrasound my records and play them just once in order to digitize them to my disk storage for playback from there.  This is for real…..no joke.  Records are delicate little creatures….just one of their faults. Would not want to subject them even to a stylus tearing through them any more than once if possible. It’s a very savage way to create music! What were they thinking 100 years ago when they came up with the idea of records? Too precious! No telling how much body mass a record looses when played. Someone ought to look into that!

Interesting approach.  But if audio, specifically hi-freq loss is the issue then it only matters if that is the outcome.  So measure what is the issue; sound (hi-freq).  As far as material loss, what if loss occurs on all grooves all shapes of waveform surfaces equally?  Like a sharp knife getting sharpened again, you have loss of metal but it stays equally sharp.  Not a perfect analogy but potentually similar.    Secondly, and I'm no materials expert, but vinyl is obviously flexible so it will be less likely to be removed than a rigid, brittle material.   Lastly, perhaps people are visualizing a force that is along/across the groove surfaces.  But as it's done in a liquid, the forces of the US wave is pressure, not shear.  Fluids, gas, cannot support shear.  Back to the variable in question; measure before and after freq content.  

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?

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.

@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. 👍

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.  

Hey, everybody needs a hobby!  

Pitter patter.