Not scientific, but I have used super distilled water to clean the discs, and the used a fiber brush while playing back to keep disc clean with regular stylus at lowest pressure usaeble.
 

> Date: Wed, 24 Aug 2011 21:27:51 -0400
> From: [log in to unmask]
> Subject: Re: [ARSCLIST] Speak-O-Phones
> To: [log in to unmask]
>
> On 8/24/2011 9:09 PM, Roger Kulp wrote:
> > Two links that might be of use
>
> Unfortunately they are not of much use in this situation.
> >
> > http://www.videointerchange.com/vintage_78s.htm#Metal%20Records
> >
> > Tracking force and stylus mentioned here.
>
> This is discussing what you were told to do back in the 1930s if playing
> them on a wind-up acoustical machine with a tracking force of 3-4
> OUNCES, which is about 85 to 120 grams. Kurt is playing these on
> ultra-modern equipment with tracking forces of about 3 grams.
>
> >
> > http://www.stevehoffman.tv/forums/showthread.php?t=129975
> >
> > The cutting machine is discussed here.
> >
> > Roger
> >
> This machine is not at all what was used to EMBOSS uncoated aluminum
> back in the early to mid 1930s. This machine shown is designed for
> cutting COATED lacquer discs. It just happens to be branded
> Speak-O-Phone but is 5 or 10 years after the use of uncoated aluminum.
>
> Mike Biel [log in to unmask]
> > ________________________________
> > From: Kurt Nauck<[log in to unmask]>
> >
> >
> > Brian and I are working our way through a stack of mid-30s Speak-O-Phone aluminum recordings. Most of these appear to be air checks of dance bands and vocalists.
> >
> > Condition is pretty good on most of them, but we're having trouble finding the ideal stylus to play them with. Best results seem to be obtained with a standard LP stylus.
> >
> > Does anyone have any experience with these? (And yes, we're riding the groove, not the landing between them.)
> >
> > Kurt Nauck