Lost-wax burnout experience

[Fred Sias]

Comments requested:
At the suggestion of an acquaintence, I started burning out a number of
small flasks during a workshop in an oven heated to 1000 degrees F.
That is, the oven was at 1000 degrees when the flasks were put in to
start their burnout. The flasks were moist (less than two hours after
investing) or had been in a bucket with wet rags over them. Later
in the week moist flasks were put in 1200+ degree oven.
Several findings:
1. Flasks did not explode or crack.
2. Burnout was quite fast: 2-3 hours.
3. Wax molecules apparently attached to steam molecules
that came off during the first 20 minutes and
there was absolutely no wax smell in room. (Did
have exhaust hood over oven but usually get smell
anyway.)
I have since talked to experienced casters that were not surprised
with this approach although it is different from the instructions
in most books.
I would appreciate comments and any better explanation of lack of
wax smell. (Peter Rowe and others ???)

Fred Sias

-------------------------------------------------------------------------Fred R. Sias, Jr., Clemson University, Clemson, South Carolina 29634-0915
Office: (803)656-5903 Fax: (803)656-5910 Email: frs...@ces.clemson.edu
Home: 120 Holly Avenue Web: http://www.ces.clemson.edu/~frsias
Clemson, South Carolina 29631 Home phone: (803)654-6833
-------------------------------------------------------------------------

[PeterWRowe]

In article <31FC1D...@ces.clemson.edu>, Fred Sias
<frs...@ces.clemson.edu> writes:

>I would appreciate comments and any better explanation of lack of
>wax smell. (Peter Rowe and others ???)
>
>

In a normal burnout, much wax is carbonizing and slowly burning in the 300
to 700 range. Creates soot, incomplete combustions products, and much
smell. If your starting at a thousand, the combustions products and waxes
etc, never get a chance to get out of the furnace before being completely
burned. Less smoke, less smell. More carbon dioxide...

As to the success of that burnout cycle, it can work, especially with
small flasks. There is no particular reason why the investement, once
properly cured, needs to be heated slowely, other than to equalize
temperatures, thermal expansion and shock throughout the flask. with a 2
inch flask or less, you probably can push the process as youve done with
reasonable success. But it is, nevertheless, asking for trouble. You are
stressing the investment more than the normal cycle, and murphy's laws
will state that you'll only get failures after you get confident in this
method, promise the finished casting in that time frame, and put in an
extremely complex hand carved wax that took much time to carve. THAT
flask will self destruct. And I'd suggest to you that your success rate
with these rapid burnouts will drop dramatically if you try it with 5 x 8
flasks.

I should note too, that some investment products designed more for the
dental industry are specifially designed for such fast burnouts. Again,
they are designed for small flasks, but I've heard they work fairly well,
and shave hours off the burnout cycle. The caster I work with is
experimenting with them now, and has had reasonable success.

Hope this helps.

Peter Rowe

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Peter W. Rowe M.F.A., G.G.
Commercial and custom jeweler and metalsmith
Graduate Gemologist and Lapidary

Opinions expressed here are solely my own....... and subject to change
according to my mood and the state of my art ....

No extra charge for smiles and friendship to those who return it
'Cause life's too short and if we're not having fun, then why be here?
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

[Douglas]

If you need a fast burnout for gold, look at KERR
Lustercast. You can cast 2 hours after you invest!

peter...@aol.com (PeterWRowe) wrote:

>>Hope this helps.

>>Peter Rowe
>>

Respectfully,

Douglas

"He who knows he knows, knows nothing.
He who knows he knows nothing, really knows."

Spooky Tooth