My thoughts on this are -
Vinyl is not porous, but shellac is, so I'll not deal with vinyl 78s, 
45s or 33s here.
For shellac records one would think that not only would ground in dirt 
and/or grit be loosened from the groove walls but any pitting that the 
dirt may have caused in the shellac would cause a microscopic loss of 
shellac at the site as well, thus possibly causing a loss in clarity and 
possibly hiss or crackle in later playings. This may not be much of a 
problem with E condition Victors, but would possibly have immediate 
adverse affects on Paramount, Grey Gull or Gennett products, among other 
labels, even in E condition! As we well know all shellac formualtions, 
even within a single company, are not the same over time.
Lacquer isn't porous but wouldn't a vibrating liquid tend to get under 
any imperfection, such as a small ding at the center hole or rim of the 
record, and begin working the lacquer away from the substrate?
So, some questions -
Have any long term comparisons been done? Such as 1) record before 
cleaning, 2) record after initial cleaning, record 6 months later, 4) 
record one year later, etc? One would have to apply both aural and 
microscopic examinations and, of course, try to keep as many of the 
variables down to a minimum as possible.
One more thing and I'll call it a day: wouldn't subsequent cleanings 
cause even more deterioration over time?
This sound like a good research project for some inquiring mind!
Malcolm Rockwell

*******

On 2/11/2013 5:09 PM, Graham McDonald wrote:
> Vinyl, shellac and lacquers, at least those that are not flaking off. As
> one of people discovered when we first got the machine (its been here for
> more than seven years) you can put CDRs in the bath. They explode or at
> least burst apart.
>
>
> Graham McDonald
> Recorded Sound Archivist
> National Film and Sound Archive of Australia,
> McCoy Circuit, Acton, Canberra  ACT  2601
> Tel:  02 6248 2192
> www.nfsa.gov.au
>
>
>
> From:   Malcolm Rockwell <[log in to unmask]>
> To:     [log in to unmask],
> Date:   12/02/2013 01:25 PM
> Subject:        Re: [ARSCLIST] Ultrasonic cleaner
> Sent by:        Association for Recorded Sound Discussion List
> <[log in to unmask]>
>
>
>
> Do you clean shellac 78s or lacquer coated aluminum discs this way??
> I can see it for vinyl discs, but shellac?
> Malcolm Rockwell
>
> *******
>
> On 2/11/2013 3:54 PM, Graham McDonald wrote:
>> We have an Elma Transonic Digital machine which has a tank about
>> 18"x12"x12" and we put just about every disc that gets transfered in it
>> first, On really grungy discs you can see the stuff coming out of the
>> grooves like little streams of smoke in the water. There is an additive
> in
>> the water, Cetramide, which I think (may be wrong) precipitates the
> grunge
>> out to the bottom of the tank. The second stage is a modified Keith
> Monks
>> cleaning machine where the suck-up arm has been attached to a rather
> more
>> powerful vacum than the original fish tank style pump. It is just there
> to
>> suck the water from the ultrasonic tank away
>>
>> cheers
>>
>> graham
>>
>> Graham McDonald
>> Recorded Sound Archivist
>> National Film and Sound Archive of Australia,
>> McCoy Circuit, Acton, Canberra  ACT  2601
>> Tel:  02 6248 2192
>> www.nfsa.gov.au
>>
>>
>>
>> From:   Steven Smolian <[log in to unmask]>
>> To:     [log in to unmask],
>> Date:   12/02/2013 11:21 AM
>> Subject:        [ARSCLIST] Ultrasonic cleaner
>> Sent by:        Association for Recorded Sound Discussion List
>> <[log in to unmask]>
>>
>>
>>
>> Has anyone recent experience cleaing records with an ultrasonic cleaner?
>> I'm particularly interested in any experience with 45s.and 78s.
>>
>> Steve Smolian
>>