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How long do investment plasters last


#1

Hullo. I am sorting out a deceased estate. Could some one let me
know how long Kerr’s investment plaster, Christobolite plaster and
debubblizers last?

Your help is appreciated.
Thank you
Felicity from West Oz.
felicitypeters.com


#2

Hi Felicity,

Sorry about the circumstances.

The debubblizer should be OK for years, possibly decades. (It’s
mostly just soap in alcohol.) It’s also worth about $5 US, so don’t
spend too much thought on it.

The investment plaster. that depends on how it’s been stored. If
it’s sealed tight so that it can’t suck water out of the air, then
it’s probably good for…2-3 years maybe? I’ve used some that was
older than that, but I wouldn’t have felt right selling it. If it
wasn’t sealed well, just junk it now, and save the bother. It’s
worth about a dollar a pound, new. (in the states.)

If you have a box that’s actually labeled christobolite plaster,
it’s gone off for sure. I don’t think they’ve used that labeling in
?40? years, maybe longer. It doesn’t really ‘go off’ but it does
suck water out of the air, and start to set up in the box. Leave it
long enough, and you’ll have a cement block. Again, it’s not worth
much in the way of fussing with.

Both of the investments are long-term risks to your lungs. Not a
problem for just cleaning out a shop, but you really don’t want to
be breathing the dust more than you can help. (google silicosis.)
Neither of them is chemically toxic. It’s just that once the dust
gets into your lungs, it causes a bad reaction due to its physical
presence and sharpness.

Talk to the local authorities about getting rid of it. Shouldn’t be
much of a problem, but rules vary from place to place.

Hope this helps,
Brian


#3

You can dehydrate the plasters by heating to between 60 and 115 deg
C and they will stay good indefinitely. the debubbler is probably a
detergent base so again it will keep almost indefinitely.

Nick R