Re: [ARSCLIST] Ultrasonic Disc Cleaning

[Kurt Nauck <nauck@xxxxxxxxx>]

At 12:11 PM 10/29/2007, you wrote:
> IASA recognises this as an acceptable cleaning method. The IASA 
> document 'Guidelines on the production and preservation of digital 
> audio objects' (TC-04) states;
>
> 'An ultrasound bath using a liquid that is not a solvent for the 
> recording surface will increase throughput. The depth need not be 
> more than the radius of a disc recording and the recording is 
> suspended on a shaft parallel to the liquid surface and such that 
> the label area is not submerged. The effect of all solvents should 
> be tested before use' (Paragraph 5.2.3.4)
>
> 'As with historical mechanical and other obsolete formats ... 
> ultrasonic cleaning may be effective. Care should be taken in the 
> selection of solvent, though a 1% solution of Cetrimide in distilled 
> water is an appropriate cleaning solution. The label should be kept 
> clear of the fluid, and the disc rotated slowly until the whole 
> grooved area has been wetted.' (Paragraph 5.3.3.4) [Note: this 
> paragraph is referring specifically to vinyl discs]
>
> The British Library Sound Archive use an ultrasonic bath for vinyl 
> and for shellac records that are particularly dirty with grit or 
> soot etc before washing on a Keith Monks machine.  The record is 
> 'dipped' with a rod passing through the spindle hole so that the 
> label is clear of the bath and is slowly turned by hand whilst the 
> bath is operating so that the surfaces are cleaned.  The liquid in 
> the bath is distilled water and a record is cleaned for typically 20 
> seconds. We don't use the ultrasonic bath on cracked or damaged 
> records but we consider both vinyl and shellac to be resilient and 
> not to suffer from the process.

Thanks for the explanation. I can see how ultrasonic cleaning would 
be suitable for vinyl, as you are dealing with an impermeable 
surface. But a shellac disc is porous - not because of the shellac 
itself, but because of the fillers. As you know, if you subject a 78 
to moisture (even high humidity), you will develop a grainy surface. 
That is due to the swelling of fibrous (porous) material imbedded in 
the surface of the shellac as it soaks up the moisture. Exposure to 
ultrasonic waves in a bath would seem to rapidly accelerate this 
process, as the solution permeates every available fissure at a 
molecular level. It may not be evident if you play the disc 
immediately after the bath, but eventually this phenomenon would 
manifest itself.

Of course, a laminated disc would be even more susceptible to damage 
- anywhere there is an opening, fluid will creep in. A crack or split 
would not need to be visible for this to occur, and the outer edge of 
the record would most assuredly be affected.

Comments and corrections welcome. (Indeed, I hope I'm wrong, as I 
have a large ultrasonic bath that could clean numerous discs at a 
time. The rotisserie feature would be easily constructed. I sometimes 
remove label stickers with spit, but this is the first time I've 
heard of using a spit to clean several discs at a time!)

Kurt Nauck

c/o Nauck's Vintage Records
22004 Sherrod Ln.
Spring, TX  77389

Website: www.78rpm.com
E-Mail: nauck@xxxxxxxxx

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