OK fellow casters. I ran into a problem today and I am not sure what
the resolution is.
First I will describe my normal process:
I normally use Ransom and Randolph investment. I mix, vacuum, pour
and vacuum within a 7 minute period. I quench my 2-1/2 inch flasks
in about 6-7 minutes. I enclose the flasks in a larger flask to
prevent fire scale. It takes slightly longer for the flasks to cool
when encased in a cover flask. Normally I would quench in 4-5 minutes
if I didn’t enclose the hot flask with a cover flask.
Here is the problem:
I was out of my Ransom and Randolph investment and HAD to cast
Sunday and Monday. My local supplier was out of 100 pound boxes of R
& R investment. He said he had several 10 pound containers filled
with the last of his R & R. He had not scheduled a new delivery
because of inventorying the store. He claimed he refilled the 10
pound containers recently from a fresh 100 pound box.
So far so good. That is until I started mixing the new investment. I
noticed several things that were different from R & R.
The normal R & R mixing ratio produced a much thinker mix. R & R
claims that their mix is thinner than other investment. Their water
to investment is greater that other products.
I normally pour my mixed investment through a kitchen strainer to
insure I eliminate all clumps that might exist. This new stuff would
not go through the strainer.
The mix seemed to set up faster.
I lived with these problems and invested several 4" 5" and one 6"
flask and several 2-1/2" flasks. But when I quenched the castings I
could hardly remove the casting from the flasks. The investment did
not break apart like R & R does. It was like concrete. I spend 10
minutes digging a simple casting out of a 2 1/2" flask. With R & R my
castings come out of the flask in a minute or two.
I cast outside and Phoenix is not known for cool summer temperatures.
The temperature in me casting area with two burnout ovens going is
118 degrees. Needless to say taking 10 minutes digging a casting out
of a flask in that temperature does not lead to a happy camper.
When I bought the stuff the dealer swore that the investment was
R&R. When I called him today to complain about the investment he
said maybe the investment was Satin Cast 20.
My question to all of you who use Satin Cast 20, do you have that
much trouble getting castings out of the flasks and if so why do you
use Satin Cast 20.
I once used some investment that has some fibers in it. I remember
that I had the same trouble with that stuff.
Lee Epperson the anti-fire scale guy.