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Delayed burnout of invested flasks


Has anyone had experience with the delayed burnout of invested
flasks? I’m talking about a 7 day delay before burnout of the flask.
If the invested flask is kept damp or is re-wetted before burnout,
can good results be expected? I would appreciate any comments you
have on experience with this.


If you are asking about a flask that has been invested and then left
to dry out for a week without beginning burnout then yes you can have
normal results from that flask. Simple place the flask in a bucket of
water for a few minutes and then let it sit for 1/2 to 1 hour before
doing your burnout.

Greg DeMark
If You Like Antique, Vintage or Custom Jewelry
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I realize my preferrd method of casting is not what most folks on
this list use but in my experience it doesn’t seem to make much
difference whether the flask is hot, cold or in between, nor does it
seem to make any difference whether a flask which I have delayed in
casting has been kept moist or not. I do one-off steam casting or
sometimes have as many as three fairly lightweight pieces invested. I
did one last week which, on the first attempt failed to cast. For
some reason the gold remained in the depression in the top. The next
day I added more metal to the melt and, without reheating the flask,
tried again and got perfect results.

Jerry in Kodiak


I take lost wax casting classes frequently and we invest on Wed.,
then burn out and cast the next Wed. I don’t believe the flasks are
subjected to any moisture prior and we cast fine. How important is
the dipping in water if the flask has sat for a while? Why the need
for extra moisture?




The advantage of having the flask moist is to help create steam
which helps push out the wax and carbon instead of alloying the
carbon to penetrate the porous Investment and possibly create
porosity. I will agree that casting is a very forgiving medium. You
can do a lot of things wrong and still get acceptable castings.

Greg DeMark
If You Like Antique, Vintage or Custom Jewelry
Visit us on the web at:



I routinely hold flasks 7 days before burnout. I hold casting
classes once per week. The first week, students make up their models
and invest them. I hold them in a cupboard for the week and when I
arrive in the AM of the next class day, I remove the bases, clean up
the sprue holes if required and put them into the oven so they can
cast upon arrival that evening.

I do not rehydrate the flasks and find they retain a reasonable
amount of moisture just from being in a closed cupboard. Our burn
outs and castings have been just fine.

Cheers from Don at The Charles Belle Studio in SOFL where simple
elegance IS fine jewelry!