Tech: Making 78's - Can someone please clarify

Subject: Tech: Making 78's - Can someone please clarify
From: GUEST,Doc John
Date: 25 Aug 09 - 09:31 AM

I recently saw a U-Tube film about this subject, which I didn't know anything about. It seems the recordings were first made by directly cutting into a disc of shellac or 'acetate' coated metal or glass. (Why acetate as it's nitrocellulose?). This disc is then electroplated to produce a 'negative' - the 'master' or 'matrix'. The fragile 'acetate' is then destroyed in the removal process and discarded. Positive'mothers' are then made from this matrix. From these are made the negative 'stampers' which produce the final shellac disc. These stampers eventually wear out so several are made. But Smithsonian-Folkways have many Asch 'acetates', several of which have been used to produce the recently releases. Some of these have been already released on LP years ago so why weren't the acetates discarded. Were two or more made in parallel recordings or was the first cut itself re-recorded. Or perhaps I've got it wrong. Help please. Thanks.
Doc John

Subject: RE: Tech: Making 78's - Can someone please clarify
From: dick greenhaus
Date: 25 Aug 09 - 12:56 PM

Acetate (cellulose acetate) was introduced to replace cellulose nitrate (celluloid) simply because of safety. Cellulose nitrate is guncotton--it burns fiercely and quickly under the slightest provocation.

Subject: RE: Tech: Making 78's - Can someone please clarify
From: M.Ted
Date: 25 Aug 09 - 01:48 PM

The "acetates" you are referring to are something different--they are trial discs that are made during the preparation of the "master lacquer" to see how well the recording transfers to disc. They aren't made of acetate, and they still use them, because they still press vinyl records--