Using Reducit

I’ve just made a rubber mold of the first casting of something I
carved. Since I’m really clumsy at carving wax, I was unable to make
the original as small as I want the finished item. I’d like to use
Reducit to make the thing smaller until it gets to the final size I
want. I have an unused box of Reducit here which came with all the
shop equipment.

The instructions for the Reducit are rather vague, referring mostly
to poured molds rather than injected ones. After reading the
directions, I have four questions.

First, what, specifically is a “Jiffy Mixer”? The instructions
pretty much insist that I use one of these to mix up the Reducit

Second, is there a good way to get this stuff into a rubber mold
meant for wax injection, besides trying to pour it (that sounds like
an effort in futility, not to mention messy…).

Third, if I do get it into the mold and end up with “flash” on the
seam lines, how do I get it off? Does the stuff melt with a wax pen,
or cut easily?

Fourth, does it burn out well/cleanly?

The list archives turned up nothing on how to use Reducit, just
places to order it. Suggestions on using this product would be
appreciated; thanks in advance.

–Kathy Johnson
Feathered Gems Jewelry
(web site is dead until the ISP fixes
a crashed drive…)

   The instructions for the Reducit are rather vague, referring
mostly to poured molds rather than injected ones. 

Hi Kathy;

Reducit is strange stuff. What I’ve done with it is to mix it up by
starting with a quantity of powder and adding a little water at a
time until I got a consistency I expected, not quite liquid enough to
pour, but such that it would flow out. You could use a turkey baster
or a large hypodermic syringe to inject it into a rubber mold, but
what I did was to pile it up on either half, staying in the cavity I
wanted filled. Then I clamped the two halves together, letting the
stuff squish out where it could. It is a light, jello like putty,
like pudding, but a little rubbery. When it sets up, you remove it
from the mold. It sits there and as it dries out, it shrinks. I
hardens to a light, slightly porous material. It’s fairly easy to
trim up the flash with burs or an exacto blade. But you can’t burn
it out of an invested mold. You have to make yet another mold from
the Reducit object. Since it’s porous, you can do a vulcanized mold
fairly easy, but an RTV mold requires that you seal it with shellac
or else you’ll be vacuming forever and end up with a mess. I found
it of limited usefullness. Perhaps others here have a better handle
on how to be get results with it.

David L. Huffman
David L. Huffman Studios, Inc.

Hi, Kathy, I thought there’d be more response about using Reducit.
Since there hasen’t been, I can maybe help a little. I have used it
successfully to reduce an image, though I was working with
press-molds for PMC, not casting. The principle should be the same.
As I understand it, and as the pictures in Rio suggest, Reducit is
only intended for making molds (negatives). You make a mold, it
shrinks, you make a wax. You can cast that, or use it to make
another Reducit mold, which again shrinks. After a couple of
generations, it’s pretty small. If it were I, I’d use Reducit til I
got the correct size, make a wax, then cast a new, metal "original"
and revert to traditional methods. The shrunken molds are a bit odd,
and the surface may not stay smooth as it dries out. I’ve also had
them curl a bit if they dry unevenly. Nonetheless, it has worked out
well for me for getting down in size. HTH!

PS I didn’t use a “jiffy mixer”, I used a fork, I think. --Noel

Hi Kathy

In my researches into methods of scaling models I’ve tried Reducit.
It seems to be water based compound with a non-combustible filler. It
sets up to a very weak and delicate gel, a long drying process
removes the water causing shrinkage. I found that it also caused a
lot of warping which was linked to the cross sectional areas of the
piece…IE very difficult to control. Slow, fast, imbedded in sand,
and vacuum made no difference though I didn’t try freeze drying. I
thought about injection using a syringe but my test piece didn’t
require it. After a few more experiments with open pours I just
carved a new smaller wax. Perhaps with more experimentation a
suitable methodology could be developed to create a useful tool.

A related curiosity is making injected waxes ~30% Larger by swelling
a vulcanized mold. An overnight immersion in white gas (Coleman stove
fuel) swells the mold very nicely though it is much softer and feels
like (very flammable) jello. There is some loss of surface finish as
the injected hot wax vaporizes some of the white gas :frowning: The mold
will dry out and return to normal sometimes but its best to use a
disposable copy.

The best method I’ve used for scaling is cadcam machining. But this
is again just carving a new wax, only without a great extra time

Jeff Demand
CadCam Modeling Solutions

Kathy, I’ve used reducit before. It works but it’s also hard to get a
good casting. The problem is, as the reducit dries it tends to curl
on thin or small parts. So you got to really keep on top of it
adjusting the piece here and there as it dries. As for what is a jiffy
mixer, It’s a mixer that you use with your drill. The makers of
reducit sell them on thier website

As for casting it. Mix it by the directions and then vacuum out the
bubbles. That is if you have a vacuum. If not try vibrating it. As
for casting it. I use a 2 part mold. The reducit is kinda thick so I
just lay one half of the mold with the deepest pattern cavity on the
table. Then pour more then I need of the reducit into it and put the
other half of the mold on top of it. Press down on it and put a
weight on it till it sets up. It’s real soft and breaks easy when you
remove it from the mold. So be carefull. Reducit isn’t the greatest
thing in the world but it might help you. It’s always been a hit and
miss thing when I use it. It sometimes take a few trys to get a good
casting that keeps its shape without curling in the drying process.
Once it’s fully dried it can be sanded. As for burning it out. I
don’t know how well that would work. Hope this helps some. Good
luck~~John Guenther

Blix Studios (sculpture and model kits)

Thank you to everyone who responded with suggestions on how to use

At this point, I’m calling our experiment with the stuff a failure.
We put Reducit into a couple different rubber molds usually used for
injection wax, including the one I really want shrunken by about 50%.
We found out that it injects into rubber molds pretty well by using a
35cc syringe (curved tip, bought at a craft store, the type usually
used for glue applications). Hubby had some fun “buttering” one mold
with Reducit by using one of my kitchen butter knives. He managed to
fill the mold up quite well (and covered most of the outside of the
mold, and a portion of the bench top with a fine coating of Reducit,
which turned to fine flakes…)

But now the stuff in the molds just won’t dry out. 36 hours later,
it’s still approximately the consistency of egg custard, moist and
slimy to the touch. I finally propped the molds open so that more air
could circulate, and several hours after doing that it’s still not
dry enough to touch or handle. I don’t think this is going to work.
Now I’m wondering how to best get Reducit slime out of my rubber

This particular wax carving project isn’t one I’m expecting to make
huge sums of money on. It’s really just a learning experience, and if
it works, it works. If not, oh well, at least I managed to complete
the original wax carving, even if it is twice the size I want. I’m
not willing to use PMC (which would be yet another learning
experience since I’ve never used it before) or CAD technology to
shrink the thing. But since I seem to be following this lesson to
the end, I’m curious to learn if there are other techniques for
physically shrinking designs that I haven’t heard of yet.

–Kathy Johnson
Feathered Gems Jewelry