Page 164 - Casting of Angels- Dave Parvin

160

Pealing an E FIX mold off of a hand without tearing the thin
The E FIX and control alginate body impressions after
removing them from the model and lifting them by one end. alginate between the fingers.

strength 16%. The elongation for both types was the same, By way of comparison, I performed the same test using
over 4 centimeters. Since all I had done was demonstrate that another alginate. I couldn't even peal it off the model without
the E F/X is stronger than it would be without the fibers, I serious tearing. When I attempted to hold it up by one end, it
hadn't really compared it to any other product. I decided to simply tore apart. The difference was remarkable. (Seethe
test another brand which I happened to have on hand. I will accompanying photographs.)
only say that this particular brand is one of the most respected If alginate isn't blended thoroughly in the manufacturing
and used among serious life casters. I have used it myself and process, soft spots can occur. The result of this effect will be
recommended it often. Its tear strength tested at only 61.5% un-gelled alginate remaining on the model's and a
of the E F/X. Its elongation was less than half. In terms of corresponding flaw in the casting. In both of the above tests,
soft, stretchy, yet tear resistant, FiberGel E F/X Grade the E F/X came off cleanly. Close inspection of the
Alginate is clearly superior. impression confirmed no soft spots. And except for a very
few small ones, the surface was bubble free.

Out of the Lab, and into the Real World About Mixing Ratios

I decided to determine if E F/X's attributes are of any real For years, I mixed alginates too thin. I had the mistaken
advantage. I had one of my assistants place a hand palm idea that thinner meant less bubbles. What it really meant was
down on a flat surface with her fingers slightly apart. I mixed that a lot ran off the subject and was wasted. I finally figured
up a few ounces of e F/X and spread it between and over the out that it could be considerably thicker than I had been using
fingers. After letting it set up, I lifted off the alginate. The and still be bubble free at the surface. Most quality alginates
thin material between the fingers came out without tearing. require about 5 ounces of alginate to 1 pound of water for the
Next I tried an even more real world application, casting mixture that I prefer. However, the ratio can vary consider-
bodies. I made two impressions of a standing front female ably depending on how much alginic acid (the costly
torso from the top of the neck to the mid thighs. For each, I ingredient) that a manufacturer uses. Many "bargain"
mixed 8 pounds of water and 40 ounces of E F/X. In my alginates may require more alginate to the pound of water-
experience, this amount of material can be mixed using a reducing the bargain.
high speed drill with a j iffy mixer in a minute flat. The E F/X It seemed to me that during the above tests on the
took just slightly longer, about a minute and 15 seconds to bodies, the mixture was just about right. But for comparison,
achieve a uniformly smooth consistency. I spread on the E I mixed three small samples using 4.5, 5, and 5.5 ounces of E
F/X, paying special attention to undercuts such as armpits and F/X per pound of water. While all three were workable, the
under breasts. It went on smoothly and stayed in place from first was just a little too runny and tended to drip while the
1/8” to 1/4" with very little running. I did not complete the last was just a little too thick resulting in a few small surface
molds, that is, I did not construct supporting mother molds. I bubbles. 5 ounces to a pound of water is right on. However, a
was more interested in seeing if I could peel off the alginate 4.5 or even a 4.0 mix would work in a container and the 5.5
ein one piece without tearing it. I could. Even though the would be helpful for serious undercuts.
alginate weighed 10-1 /2 pounds, I could lift it by one end
without its pulling itself apart. Holding it up to a light, the Delayed Shrinkage
thickness was uniform.
For one of these I used 80 degree F. water and the E F/X Ed McCormick had told me that in his experiments E F/X
set up in 6 minutes on a warm body. For the other I used 90 seemed to retain moisture and delay shrinkage of the mold.
degrees water and the setting time as 5 minutes.