Flasks Dewaxing and Burnout

Now that I have this new kiln that holds 16 2x4" flasks (compared to
my old one that held 4 2x4" flasks), I’m finding that my casting
process is being radically affected.

First, my homemade steam dewaxing pot only holds 4 flasks at a time.
Once flasks have been steam dewaxed, is it alright for them to sit
at room temp for a few hours before starting a burnout cycle? If not,
how does one steam dewax 16+ flasks at a time?

Second, can flasks be stacked in a kiln for burnout? This kiln could
actually hold 9 more 3x2" flasks if they were stacked above the
openings between the bottom layer of flasks. Is it OK to do this?

Thanks, Orchid!

Kathy Johnson
Feathered Gems Pet Jewelry

Hi Kathy,

You should have no problem dewaxing four flasks at a time and
letting the dewaxes flasks wait until all are dewaxed. After dewaxing
the flasks should sit for a couple of hour before placing them in the
burn out oven.

I suggest you buy some ceramic blocks to place under your flasks.
This will allow for better burn out. You can stack flasks. You should
stagger the flasks so that the opening of the top flask is over the
edge of the two flasks. I would not stack flasks too high along the
back wall and corners of your burn out oven. Heat gets trapped
between the wall and tall flasks. This can cause the coils to burn

I will send some drawings off list.

Lee Epperson

Hi Kathy.

Oh the fun of ‘scaling up’ an operation!!! You might need to build
another de-waxer. Steam de-waxed molds should be burned out before
drying out.

If you can afford the test (use brass instead of gold/silver) I
would run multiple de-waxes and begin your burnout as usual. Your new
oven should be designed to handle the extra load with some changes to
the burnout cycle. Extend the low end of the cycle by 1-2 hours to
slowly heat the molds.

Don’t forget that an invested mold significantly lags (by up to 1-2
hours) the indicated temperature of the oven unless the control
thermocouple is buried in an invested mold.

You can stagger stack the molds so the tree openings are exposed.
Happy hunting…

Paul Finelt, CIRM
PF Associates, LL.C.

If it’s going to take a while to get them all dewaxed, let them cool
a bit, then bag them in plastic bags before they dry out to keep the
moisture in until they are all ready to go.