Film-Tech Forum ARCHIVE: Were shellac phonograph records inflammable?

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Posted by Leo Enticknap (Member # 534) on 02-01-2013, 09:09 AM:

This story in my local paper (basically, an advertorial for an independent, volunteer-run cinema in a small town in north-east England) caught my eye, and specifically this note of a fire at a rival theatre:

quote:
By 1927, it had acquired a balcony, talkies of the town, but had also gained competition. When the Gaiety up the road mysteriously burned down three years later, the fire brigade found highly inflammable gramophone records placed carefully on every seat.

This sounds not quite right to me. Most records at the time were a shellac/mix filler compound. As far as I know, neither are inflammable. At least, I've never attempted to ignite one, though I might try over the weekend as an experiment.

I'm wondering if (a) records made for distribution to theatres were pressed on some sort of non-brittle base to avoid breakage in transit (nitrocellulose on a metal base, for example), or (b) this was incorrectly reported, and in fact the arsonist put something else on every seat, e.g. bits of nitrate film. If this was in 1930 there could have been Vitaphone discs around, but they were pressed on shellac, too - I've handled some.

Any thoughts?

Posted by Jim Cassedy (Member # 4115) on 02-01-2013, 09:43 AM:

I'm no expert on this topic, but I do know that there is (or was?)
such a thing as "nitrocellulose shellac". I'd imagine that a disk
made from this compound would be somewhat flammable.

I have about half-a-dozen Vitaphone disks here and all of them
appear to be "regular" shellac over a metal base.

Posted by Mitchell Dvoskin (Member # 751) on 02-01-2013, 09:50 AM:

> I've never attempted to ignite one, though I might try over the weekend as an experiment.

I've always have assumed that these records were flammable being that shellac is made from organic insect secretions mixed with alcohol, both of which are flammable. However I also have never tried to ignite one. I would be curious as to which of us is correct.

Posted by Leo Enticknap (Member # 534) on 02-01-2013, 10:04 AM:

OK ... I feel an experiment coming on. A few years ago I bought a job lot of 78s on Ebay for next to nothing, largely for turntable testing purposes. Some of them are so badly scratched and mould-contaminated that I think I could sacrifice one in the name of science with a clear conscience. Besides, it'll give me an excuse to test the video function on my new D-SLR. Watch this space...

Posted by Randy Riddle (Member # 3989) on 02-01-2013, 12:37 PM:

I'm a collector of radio transcriptions - 16" discs used at radio stations in the 1930s through the 1950s for programming - and there were types of discs that were flammable.

Back before tape, one could record a radio show or special event on lacquers - aluminum (or glass during the War), covered with a material that would be etched by a record cutting lathe.

Some formulas for these did use nitrocellulose in the mix and could be flammable. Those without this in the mix were labeled as "safety" discs.

I had one disc that was flaking and decomposing and, as an experiment, I put a some of the flakes in a glass dishes and lit a match to them. Poof!

Posted by Stephen Furley (Member # 1277) on 02-02-2013, 09:03 PM:

Shellac can burn, but it's not highly flammable. It was one of the ingerdients of sealing wax; I don't know if it still is. A stick of sealing wax doesn't burst into flames if you apply a match to it, but it will burn to a limited extent.

Shellac records contain various other things, filler, and carbon black for example; I think the carbon black makes it flow better in the press. Pure shellac would be too brittle to make disks from.

Shellac will disolve in alcohol; that's how you make French polish. I've seen 'modern' vinyl records being pressed; no solvent is involved, granuals of vinyl are pre-heated to form a 'biscuit' which is placed on the lower matrix in the press. I don't know if shellac records were made in the same way, or if any solvent was used, but if any alcohol was involved it would certainly have evaporated. If any remained the record would be soft and sticky. The presses which I saw were steam heated and water cooled, though I've heard that electrically heated ones also existed. They were pretty hot.

I've also seen master lacquers being cut; these were highly flammable lacquer on a netal, I think aluminium, base. The packaging was clearly labeled as being highly flammable. This was a long time ago, early '70s, I don't know if they still are.

Posted by Leo Enticknap (Member # 534) on 02-03-2013, 04:06 PM:

Thanks to snow and a howling gale, my little science experiment had to be postponed. [Frown]

quote: Stephen Furley
I don't know if shellac records were made in the same way, or if any solvent was used...

This video is maddeningly elusive on that question. It describes the mixture as being of shellac, a resin of some description and 18 other ingredients, with steam being injected into the actual press to keep it malleable during the pressing itself.

quote: Stephen Furley
I've also seen master lacquers being cut; these were highly flammable lacquer on a netal, I think aluminium, base. The packaging was clearly labeled as being highly flammable.

Nitrocellulose. Yup - nitrate is alive, well and still being used!

This local rag story still doesn't seem quite right to me. Shellac pressed discs were probably no more inflammable than paper, and surely there wouldn't have been enough transcription/dubplate type discs on hand in a cinema to put one on every seat of its auditorium?

Posted by Randy Riddle (Member # 3989) on 02-05-2013, 08:14 PM:

quote: Leo Enticknap
This local rag story still doesn't seem quite right to me. Shellac pressed discs were probably no more inflammable than paper, and surely there wouldn't have been enough transcription/dubplate type discs on hand in a cinema to put one on every seat of its auditorium?

The article notes that it burned three years later than 1927 - about 1933 or '34.

It's possible, but maybe not with phonograph records on every seat.

Lacquers (aluminum coated discs) didn't really start getting used until the mid-thirties. If this had happened later, having a big quantity of "throw away" lacquers from a radio station or studio wouldn't be unusual. They could only be used once - if you recorded a radio show for playback at a later time or had a bad recording, the discs would just be discarded. During the War, there were services that would take the discs, melt off the coating and recycle the aluminum or recoat them so they could be reused.

There was no standard formula for shellac discs - some might have been more flammable than others.

Another possibility that could be used in the early 30s if I wanted to start a big fire would be the many experimental plastics discs made by different companies. Some were used for syndicating radio shows - it was a way to get a quieter surface for playing the discs on radio. Some were pressed for release to the public in different colors as a gimmick. Here in the US, a company called Flexo unsuccessfully tried to market these types of discs to broadcasters.