On 15/12/2015 20:46, Dave Platt wrote:
Adrian Tuddenham wrote: "(If the surface is mud-cracked or there is red powder
on it, the disc will be in a dangerous condition and you need to seek
specialist help to avoid starting a disastrous fire.)"

😱 ??

Setting a record on fire just by playing it?

If the disc is old enough that the cutting surface was celluloid, or
cellulose nitrate (rather than the cellulose acetate used in later
years) then it might be bad juju!

Celluloid deteriorates with age - the camphor escapes and you're left
with just cellulose nitrate, which becomes increasingly brittle.

Cellulose nitrate is known by another name - "guncotton". Also "flash
paper". It's a primary ingredient in smokeless gunpowder.

If something made of celluloid or cellulose nitrate has deteriorated
to the point where it's forming a powder... well, that powder might be
touchy enough that even a static-electric spark might ignite it, and
FOOM.

I'd also be concerned about diamond-stylus-to-groove friction - there's
a *lot* of pressure on that tiny contact surface. I've heard that the
heat generated during playback of an LP is actually sufficient to melt
a very thin surface layer of the vinyl!

On the other hand, if it's a true "acetate" disc (made with cellulose
acetate rather than cellulose nitrate) the flammability problem would
be much less. If this material is deteriorating there might be a
distinct odor of vinegar, as the acetic acid dissociates from the
cellulose.

As to playing the disc... the cat's meow might be to gain access to an
ELP laser turntable, which doesn't use a physical-contact stylus at
all. No wear... but not cheap nor common.


There is also a step and repeat low power microscope multi-capture
system , then auto stitched images, then wiggles converted to sound.