water temp for investing

how terrible would it be for the mold if i used 90(F) degree water when
i mix my investment.

i understand that working time is reduced.

does it damage the mold?

btw i am casting sterling pendants with the smallest part an 18ga wire
loop.
thickest part 1/8th inch.
overall about the size of a quarter.
im new so dont kill me for asking a dumb question

On Fri, 03 Dec 2004 22:40:00 -0800, in ¸õ "walt" wrote:

how terrible would it be for the mold if i used 90(F) degree water when
i mix my investment.

i understand that working time is reduced.

does it damage the mold?

btw i am casting sterling pendants with the smallest part an 18ga wire
loop.
thickest part 1/8th inch.
overall about the size of a quarter.
im new so dont kill me for asking a dumb question

As i said once, "dumb" questions are mostly those that should have been asked, but were
not, or those which have been asked and answered, perhaps many times, and whose answers
are still ignored, and in the latter case, the question isn't dumb, just the folks who
don't pay any attention to good advice and then wonder what went wrong. (This is not
the same as those who listen to good advice, and decide to try the "wrong" method
anyway, just to see what happens. Many fine experts have been prooved wrong this way,
and new innovations found as well.)

But I digress...

Normally, the water for investing should be at room temp. Heating to 90 degrees will
shorten your working time by a LOT. Perhaps to too short a time to get the job done
properly. You don't want to be still pouring a flask as the investment is starting to
thicken up...

However, there's a balancing equation. More water can slow the working time. So it's
possible to mix investment with 90 degree water, if you use a bit more of it. You'll
have to find the exact ratio by trial and error. What you'll find is that the
investment slurry is more liquid, and will pour more easily. The thinner mix also will
mean it's easier to get bubbles to rise and "go away", which compements nicely, your
reason for wishing to try warmer water. So the combination may work well indeed. The
downside to this is that the resulting investment, once dried and cured, will be
slightly less dense, and thus perhaps less strong. Now, this too has a good side. The
more porous investment will be a little easier to fully burn out, as gasses can
dissipate more easily. And it may be slightly easier to get full filling in the flask
again due to greater gas permiability of the investment. But it does seem, in my
experiments with it, a bit less strong. You'll want to pay close attention to not
spacing parts too close together, which would form weak thin bridges of investment in
the mold. And try to avoid sharp joins from sprues to models, as those will lead to
sharp projecting corners of investment in the molten metal stream, more easily being
broken off. So sprue neatly, joining sprues with a slight filet, creating a gentler
radius on those formed corners in the investment. And leave a little more investment
covering the models at the top of the flask, to avoid blowouts.

You can find a fine account of how this can be done, along with a whole slew of other
entertaining and informative articles on one section of Precious Metals West's web site.
They're a refiner and metals dealer worth knowing about, by the way. Anyway, one of
their people is an interesting guy names Marc Robinson. I'm never quite sure whether
I'm more impressed with his knowledge of his subject, or his ability to write about it
in a manner that often leaves me laughing. Anyway, it's worth checking out. The
articles seem just all run one after the other on one very long page. Go down about half
way down the page to one titled "curing altitude sickness", and you'll find the
description of using hot water to mix investment. The URL for those articles is:
http://www.preciousmetalswest.com/marcs'.htm

Have fun.

Peter Rowe

Peter W.. Rowe, wrote:
The URL for those articles is:
http://www.preciousmetalswest.com/marcs'.htm

Have fun.

Peter: Thanks for posting that URL. I'm getting back to doing some
casting again, and the info on that whole site was one of the best
resources I have seen in a long time. Thanks!

On Sat, 04 Dec 2004 07:46:26 GMT, "Peter W.. Rowe,"
wrote:

More water can slow the working time. So it's
possible to mix investment with 90 degree water, if you use a bit more of it. You'll
have to find the exact ratio by trial and error. What you'll find is that the
investment slurry is more liquid, and will pour more easily. The thinner mix also will
mean it's easier to get bubbles to rise and "go away", which compements nicely, your
reason for wishing to try warmer water.
Alternatively, you can slow the working time without adding more
water; a grain or two of ordinary table salt will have that effect.
Less is more, in this case; I can remember slowing down the setting
time of 5,000-pound batches of investment material by several minutes
by adding less that a pound of salt to the mix...


Blessed be, for sure...

[90 degrees isn't all that warm. What does one do in summertime, add ice? In
reply to the original question, I usually agree with everything Peter says,
but having tried some home-made alternatives, I don't think that inadequate
vacuum is worth messing with. When I got almost -but not quite all the way-
to 29", I found more bubbles on the pieces than when I didn't use it at all.
Vibration just lodged more bubbles on downward-facing surfaces.]

Andrew Werby
www.unitedartworks.com


"Peter W.. Rowe," wrote in message
...
On Fri, 03 Dec 2004 22:40:00 -0800, in ¸õ "walt"
wrote:

how terrible would it be for the mold if i used 90(F) degree water when
i mix my investment.

i understand that working time is reduced.

does it damage the mold?

btw i am casting sterling pendants with the smallest part an 18ga wire
loop.
thickest part 1/8th inch.
overall about the size of a quarter.
im new so dont kill me for asking a dumb question

As i said once, "dumb" questions are mostly those that should have been
asked, but were
not, or those which have been asked and answered, perhaps many times, and
whose answers
are still ignored, and in the latter case, the question isn't dumb, just
the folks who
don't pay any attention to good advice and then wonder what went wrong.
(This is not
the same as those who listen to good advice, and decide to try the "wrong"
method
anyway, just to see what happens. Many fine experts have been prooved
wrong this way,
and new innovations found as well.)

But I digress...

Normally, the water for investing should be at room temp. Heating to 90
degrees will
shorten your working time by a LOT. Perhaps to too short a time to get
the job done
properly. You don't want to be still pouring a flask as the investment is
starting to
thicken up...

However, there's a balancing equation. More water can slow the working
time. So it's
possible to mix investment with 90 degree water, if you use a bit more of
it. You'll
have to find the exact ratio by trial and error. What you'll find is that
the
investment slurry is more liquid, and will pour more easily. The thinner
mix also will
mean it's easier to get bubbles to rise and "go away", which compements
nicely, your
reason for wishing to try warmer water. So the combination may work well
indeed. The
downside to this is that the resulting investment, once dried and cured,
will be
slightly less dense, and thus perhaps less strong. Now, this too has a
good side. The
more porous investment will be a little easier to fully burn out, as
gasses can
dissipate more easily. And it may be slightly easier to get full filling
in the flask
again due to greater gas permiability of the investment. But it does
seem, in my
experiments with it, a bit less strong. You'll want to pay close
attention to not
spacing parts too close together, which would form weak thin bridges of
investment in
the mold. And try to avoid sharp joins from sprues to models, as those
will lead to
sharp projecting corners of investment in the molten metal stream, more
easily being
broken off. So sprue neatly, joining sprues with a slight filet, creating
a gentler
radius on those formed corners in the investment. And leave a little
more investment
covering the models at the top of the flask, to avoid blowouts.

You can find a fine account of how this can be done, along with a whole
slew of other
entertaining and informative articles on one section of Precious Metals
West's web site.
They're a refiner and metals dealer worth knowing about, by the way.
Anyway, one of
their people is an interesting guy names Marc Robinson. I'm never quite
sure whether
I'm more impressed with his knowledge of his subject, or his ability to
write about it
in a manner that often leaves me laughing. Anyway, it's worth checking
out. The
articles seem just all run one after the other on one very long page. Go
down about half
way down the page to one titled "curing altitude sickness", and you'll
find the
description of using hot water to mix investment. The URL for those
articles is:
http://www.preciousmetalswest.com/marcs'.htm

Have fun.

Peter Rowe