Composition of shellac records

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chunnybh
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Re: Composition of shellac records

Post by chunnybh »

Thank you OrthoFan and everyone else too for all the info, very enlightening and just what I was looking for.

I tried to de-laminate an Australian Decca with boiling water and soaking over a few days. It did de-laminate at the edges exposing the layers. Pic attached. A hard solid center core with paper between the core and the brittle recording surfaces. I can't see any trace of an aluminum foil.

I have also read somewhere that laminated records have less noise not only because of the higher grade of shellac but also because of the cushioning provided by the paper.
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Re: Composition of shellac records

Post by Lucius1958 »

Phototone wrote:
bigshot wrote:Diamond Disks are laminated too, aren't they?
Well, Diamond Discs have a core and a varnish applied that takes the impression from the stamper. I don't think they could be called laminated because A. There is no barrier between the core and the varnish and B. The varnish is applied to the core before the blank is inserted in the press. The surface varnish bonds with the core without any intervening paper or other divider.
The early "transfer" discs could be regarded as laminated, since they were pressed on a varnished celluloid surface that was bonded to the core.

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Re: Composition of shellac records

Post by Marco Gilardetti »

CarlosV wrote:Italian La Voce del Padrone were laminated, and high quality.
I'd say that most Italian records were laminated. CETRA and Parlophone brand records, which are the most common, were also both laminated. Instead, most Italian Columbia records look as if they were not laminated (which doesn't necessarily mean that all of them were not laminated).

In my collection I also have few samples of laminated records in which the central layer of material was compltetely omitted, and the record is made in a thick central cardboard circle covered in black shellac (nothing to do with Durium type records). I believe that these records were issued for few years by the end of WWII.

Laminated 78s can be a double edged weapon at times: when the outer shellac layer is uneven due to a pressing defect, the paper might resurface in areas where the layer of shellac is especially thin, and the music might get quite unlistenable or very noisy.

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Re: Composition of shellac records

Post by chunnybh »

So, why were laminated discs made?. Was it just to obtain superior quality?.
Pressing a normal record seems a lot easier; a blob of softened shellac mix in a press with two masters.
The laminates seem to be a lot more complicated. A hard core, glue to fix the paper/foil and a thin layer of high grade shellac mix on each side. Already prepared biscuits with softened shellac placed into a press. Just the handling of the biscuits would have needed skill and care.

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Re: Composition of shellac records

Post by Marco Gilardetti »

My educated guess is that by doing so the core could be shellac-less (or almost shellac-less) and thus much cheaper, eventually counter-balancing the more complex and costy pressing technique. Especially in countries like Italy, which was subject to economic sanctions and import blocks, reducing the amount of shellac imported from UK was crucial.

However, in my opinion, pressing the core and the paper circles is possibly not as difficult and costy as you describe. The papers may be held on the pressing plates, and then pressed against the blob of the inner core. If the core material is mildly adhesive, the paper will attach to it without any further workmanship. If you've ever seen how paper labels are pressed against today-made LPs in "just one move" you got an idea. It could possibly have been quite the same.

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Re: Composition of shellac records

Post by CarlosV »

chunnybh wrote:So, why were laminated discs made?. Was it just to obtain superior quality?.
If you take into account that the laminated discs were put in the market by Columbia in the 1910's, and the contemporary advertisements, the motivation was indeed to get a higher quality product and a consequent commercial edge over the competition, with their "New Process" records. The key to understand this is to check the prices of the records, which were outrageous and highly lucrative products, so an increase in their production costs would be offset by selling either at higher prices per unit or increasing the volume of sales.

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Re: Composition of shellac records

Post by epigramophone »

While looking for something else I came upon a reference to an article by an un-named former employee of RCA Victor, in which the composition of the records is given as :

Shellac...............13.6%
Vinsol.................8.7%
Congo Gum..............0.9%
Filler................74.9%
Carbon Black...........1.3%
Zinc Stearate..........0.5%

If you have been paying attention so far you will have noticed that the total is not 100%, because the figures have been rounded down to one place of decimals.

I understand that Vinsol was a low melting point moulding modifier, Congo Gum a flexible binder and Zinc Stearate a lubricant for mould release. The filler was said to be 50/50 powdered limestone and powdered slate.

We may also assume that any faulty pressings and production waste were recycled back into the mix.

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Re: Composition of shellac records

Post by CarlosV »

epigramophone wrote: Shellac...............13.6%
Vinsol.................8.7%
Congo Gum..............0.9%
Filler................74.9%
Carbon Black...........1.3%
Zinc Stearate..........0.5%
The filler was said to be 50/50 powdered limestone and powdered slate
Based on that mix, we have been misnaming these records all this time: we should call them stone records (with some shellac)!

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Re: Composition of shellac records

Post by chunnybh »

Thank you so much for that recipe.
We may also assume that any faulty pressings and production waste were recycled back into the mix.
I know during the war, in the UK at least, you could not buy new records unless you took in another for recycling.

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Re: Composition of shellac records

Post by epigramophone »

Shortage of raw materials, especially shellac, during WW2 meant that the only way record manufacture could be maintained was by re-using old material. It was estimated that in the UK approximately 10 million old records were lying unloved in cupboards and attics, so in 1942 a nationwide salvage campaign for gramophone records was launched.

Announcements appeared in all the major newspapers, on the radio and on cinema newsreels. Famous recording artists from Harry Roy to Richard Tauber gave their support. The campaign was successful, but "The Gramophone" magazine of September 1942 expressed the hope that any really scarce and interesting records would be preserved. We can only wonder what treasures were lost.

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