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.
Hi Lee, I’m not a casting expert, but this almost sounds like
platinum investment. I’ve used both R&R and Satin cast and haven’t
had that problem. What I run into once in a while is the powder not
being mixed enough while in the barrel. This doesn’t have an effect
on the removal though?
I have used Satin Cast 20 for about 20 years and never experienced
the problem you mentioned.
Since I do not use the R & R investment I do not know if there is a
different mixing ratio or time for mixing but it does sound like the
amount of water used for that investment was wrong.
Back in the early 1980’s I met the head of Swest in Dallas. He was
also an experienced caster. He was the one that recommended Satin
Cast 20 to me because it was an investment that was pretty easy to
use. I was told that there are wetting agents added to the Satin Cast
20 that helped with the mixing process. In any case I have used that
product since then and find it to be practical for me.
I have used R&R Ultravest at least two years old and have never had
problems like you describe. Satin Cast 20 works in a very similar
way. Both use 40:100 mixing ratios. About the only changes I have
noticed are different setting times when using unknown water at a
workshop or when the weather or altitude is unusual. I had some
20-year old R&R that wouldn’t set at all.
Both Ultravest and Satin Cast 20 act about the same way when
breaking out after casting. Never had a problem with either.
I wonder if your dealer could have put pure plaster of Paris in your
box or mixed in some plaster of Paris. Jewelry invvestment is
usually about 30% gypsum or plaster of Paris. If I remember
correctly, pure plaster of Paris sets faster than jewelry investments
which would explain your thick pour. I think you got contaminated
investment or plain plaster of Paris. Other explanations don’t make
sense.
I use satin cast 20, and have for years. It sounds to me that, from
your desciption of R&R, there is not much difference.
What you have described sounds like you got something like Diamante
investment. I use Diamante for casting stones in place, and it is a
thicker mixing, and very hard curing investment. When using it, I
usually let my flasks air cool, and them tap break the castings out.
When I have used it as a regular investment ( when out of stain
cast), I found as you did that when I tried to quench it, it just
doesn’t work well. Very hard, and doen’t break down in the water.
I use Satin Cast 20. The slurry is like a very thin pancake batter. I
quench when color leaves the button. Investment comes boiling out of
the end of the flask. Or I knock it out by hammering the sides of
the flask. The rest is a brass rod, sparex, toothbrush and steamer. I
don’t recognize the trouble you are having.
I store all my investment inside the house. My inside house
temperature is set at 72 degrees. The investment never sees the heat
of the day until I take it outside and start my mix. It has no time
to get hot. I use purified water stored inside my house. Again it
does not see the heat of the day until I mix it. Neither investment
or water is allowed to sit outside before mixing it. They do not have
a chance to heat up from the outside ambient temperature any more
than a degree or two before the mix is vacuumed and poured.
I quench in several 30 pound kitty litter plastic containers. When
one gets warm I move on to the next. I fill each one just before
quenching. That provides ground water temperature not heat of the day
temperature to the water. The temperature of the water from the
outside hose is 84 degrees.
I have cast in the summer for at least 30 years and have never had
this problem before. One day I cast when the registered temperature
was 122 degrees. My casting area temperature was around 128 degrees.
The only affect the temperature has is on the filled flasks. They dry
out faster so I place them in the burn out oven a little sooner that
I would if it was winter.
I try to complete my investment cycle in 7 minutes. I mix for 1.5
minutes with an electric mixer at high speed. I vacuum for one
minute after the investment pancakes. I vacuum the flask for one
minute after the first bubble appears. I can invest two sets of
flasks in the 7 minutes I allow my self. I pour the investment
through a kitchen strainer. That procedure has work for me for 30
years.
Oh well I won’t be casting for a while. Its time to grind, solder
and finish stuff. I have four big pots to inlay stone in and finish.
It sounds to me that you just got used to using investment that had
become relatively saturated with water. Investment is highly moisture
sensitive, that’s why it’s so hazardous to human health; it’ll absorb
moisture anywhere it can.
It’s probable that as your investment aged it absorbed a lot of
moisture, throwing the ratio of water-to-powder off and generally
producing a thinner slurry. Thicker, dry slurries do set up faster
and are harder than thinner, wetter slurries because the plaster when
set up and burned out is denser. This is why it’s recommended to use
a thicker, drier slurry on large waxes with few details and more
detailed, delicate waxes call for a thinner slurry. I’ll bet if you
try again and use a little more water you’ll be a lot happier.
At I.J.S., we sell Satin-cast 20 and Hoben Goldstar XL. We do not, no
way never, nohow “refill 10 pound containers from a fresh 100# box”.
It’s your money for your investment, which we staunchly believe
should be unmolested 'til it gets to you. Any violation of a
container happens by the blade of a forklift, and that container is
written off.
You have to strain for clumps?!? We warn our clientele to keep the
box sealed and the plastic inner bag tupperware-burped, especially in
humid climes. We warn people to have dry hands before going in the
container. In the catalog that so few read.
I can’t speak to consistency of pouring investment or setup times.
Breakout occurs within earshot of my office, near our casting
facility. I hear no difficulties. And our guy can cuss worse than a
sober sailor.
Fibers? Special blends for larger pieces, sculptures. I.J.S. had
some for special orders. By design, it has to hold a heavy load. It’s
a given that breakout will be tough.
A big thanks to all of you who sent me a post related to my
investment problem.
I believe the supplier sold me Platinum investment.
I never buy repackaged stuff. Unfortunately I was in dire need of
investment and was promised that repackaging occurred just recently.
I didn’t mention in my post that I used the last 5 pounds of the R&R
investment I had left from my last casting. I had no problem with
that investment. In Arizona moisture is not as much of a problem as
it might be in Minnesota.
Needless to say the dealer will be getting all the remaining stuff.
I will recommend that they seal the plastic containers with tape
immediately after repackaging and mark the manufacture on the
containers.
I used Satin Cast 20 for many years. I was very content with the end
result. I quit using Satin Cast 20 many many years ago when they
changed their formula without telling their users. I lost 5 out of
six original models because I didn’t know about the mixing ratio
change.
The Investment I got his time was definitely was not Satin Cast 20
or R & R.
If some times you face a problem of hard investment after casting, i
use 50 percent phospheric acid, that is put my tree in 50 percent
phospheric acid for 15 minutes,so the investment gets really soft
and easy to remove with water pressure. Safety for phospheric acid I
use borosil bowls to store and use this acid, it is not corrosive to
the precious silver and gold, if heated this acid in borsil bowl to
40 degree centigrade it removes the oxide film totally. Nuetralise
the tree after removing from the acid in baking soda solution till
the reacion stops. I am using this mithod since last 15 years now for
all my gold and silver castings, to soften the investment powder.
Since last more than 15 years now,I am using my own formula of
investment powder, 27 percent dental stone plaster and 73 percent
silica sand (quartz powder 500 mesh),so my investment is quite hard
but i get the soothest castings like any commercial investment
powder,surprisingly very true and i have saved lots of money in last
15 years by using this simple formula which I experimented and was
succesful and very happy till today.The cost of silica sand is
around 20 cents per kilo and dental stone plaster one Dollar per
kilo.
Wishing all my orchidian friends a total Health - Mental, Physical,
Spiritual and Social.
It's probable that as your investment aged it absorbed a lot of
moisture, throwing the ratio of water-to-powder off and generally
producing a thinner slurry.
That is why I mix my investment by look and feel rather than by
weight. There can be a lot of variation from the top of my
investment container to the bottom, when I finally get down to it. I
dip a finger in it; can I see my skin color through the white
covering? It takes practice, but I like mixing by feel best.