ultrasound cleaning?

Since I sell ultrasonic and megasonic equipment for semiconductor manufacturing, I have considered trying to use one for LP cleaning. I have no doubt as to it's ability to perform the clean, but I have concerns about damage. I'm not saying it will, but only that it has the potential.

The cleaning mechanism in an ultrasonic is cavitation. Basically the formation and collapse of a gas bubble. At the instant the bubble collapses, the amount of energy released is very high. Typically bubbles collapse at one point and a micro jet of liquid is released at very high velocity. The energy is so high that it can damage many materials including stainless steel. Because of the damage, Ultrasonics for cleaning silicon wafers was phased out years ago and replaced by Megasonics which operate in the 1MHz range as opposed to the 25-50kHz that a typical ultrasonic operates at.

I think Megasonics would really do a great job on vinyl except for a couple of problems. The first is that they are really expensive. One that was large enough for an LP might be $35,000 or more. The other factor is that the high frequency can penetrate plastic materials and cause them to melt from the inside out. I think if you used low power and kept the vinyl moving you could probably avoid the melting, but the cost is hard to deal with.

My advice for anyone looking at ultrasonics for record cleaning would be to start with some vinyl that you picked up cheap and do some experimenting with chemicals and power if the tool has the ability to vary power. Keep the vinyl moving when in solution to minimize exposure time. Come up with a recipe that you think does a good job of cleaning and then repeat the clean a bunch of times and see if it damages the record after a number of cleans.

I'd like to do some tests at work, but the stuff we have is used for ultra critical cleans and if someone saw me with a record in one, I'd be history.

Good stuff on the dangers of US. I was almost going to go buy one this w/e.

While I would not want to damage a record, if that is the only risk, I might be able to live with it. For replaceable records and maybe forgoe for the special ones. However, if a micro-bubble could remain behind and damage a stylus, then even if remote risk I would be much less inclined to consider. Is stylus damage possible? Or is it mainly the record which risks damage?

If stylus damage is possible is there a time period after say washing/drying/vacuum etc... where risks dissipates. In which case could do ultra-sound clean then, wash/dry then putaway. Play l8r.

Again, thks for info.

Good site for additional pics of the Asia model.

http://www.asahi-net.or.jp/~zi2a-hsgw/usonic.htm

click on the links to see various profiles.

I have to agree with Ogsarg that there is strong potential to trash an LP via ultrasonic cavitation.

I formulate water-based cleaners for aerospace and general industrial cleaning. The majority of these cleaners are used in ultrasonic tanks.

Several parameters are relevant to preventing damage;

1. Duration of exposure to ultrasonics - leave the parts in too long and erosion damage can occur, especially on softer substrates.

2. Frequency choice - if ultrasonics is to be used on an LP, you cannot use 20-25 kHz. A good starting point would be 40 kHz but even higher is better. As the frequency is lowered, the cavitation becomes more violent. Never clean aluminum in a 25 kHz ultrasonic tank because you will literally tear the metal apart. 40 kHz is safe on aluminum as long as the exposure time is not excessive; try to limit exposure to 5 minutes max. Vinyl is softer than aluminum so I would be very concerned about even using 40 kHz. However, 40 kHz can still be safe if the power input is low. There are also ways to mediate the cavitational energy through racking and cleaner design, etc.

3. Temperature - only clean at room temperature on vinyl but this should be obvious because heat will warp records. Industrial ultrasonic cleaning is often run at 120 - 170°F.

4. You generally want to use a foamy cleaner because a foamy cleaner enhances cavitation. An aqueous cleaner that becomes cloudy when diluted and is low foaming will not yield as good cavitational performance because the design does not enhance cavitation. Conversely, a low foam cleaner can still work, especially if it dampens cavitation just enough to minimize erosion of the vinyl.

5. A rinse step should follow the wash step if possible which adds another tank.

There probably are a couple other factors worth going into but I'll leave it as is for now.

I think this instrument will be too expensive to be practical for nearly all vinyl lovers. I think the potential to screw-up the record is too great. You would be better off buying or custom building a vacuum cleaning unit and using a good commercial cleaner such as the RLL product line than to venture down the road of ultrasonics.

Mr. Kidknow

Ogsarg and Mr. Kidknow,

MANY thanks for your input. As one who has been interested in the pending U/S RCM from BentAudio since it was first announced, I'm paying close attention. I'm going to point this thread out to John Chapman so he can consider the issues you've raised. (one hopes he has done so already).

If I got such a machine, I'd clean a junk LP repeatedly, increasing cleaning times and/or intensities to test for possible vinyl damage. IOW I'd *try* to wreck the LP, just to learn the limits for safe use.

As I mentioned, the design does keep the LP moving so that should help, according to Ogsarg. I believe it may also include a rinse tank.

Spinitch, if anything was left behind on the record it would just be some of the solution. If it's safe for vinyl it's hard to imagine it could damage a stylus. No exploding bubbles (imploding actually) once the U/S energy is turned off.

Dougdeacon,

No problem in at least trying to contribute on this subject.

Although I have strong reservations about using ultrasonics on vinyl, this doesn't mean that a system cannot be designed that is quite safe. Bent Audio and any other companies that are investigating this must be putting a good amount of time and observation into the concept in order to eventually know if their product will be safe or not.

I just have serious concerns that the number of variables that can be missed in product developement will come back to haunt users. Due to the likely high cost of such equipment, those users will be pissed-off bigtime is something does go wrong.

Personally, I'll stick with brushing and vacuuming since it is an already proven technology.

Mr. Kidknow