I see that this forum is empty and lonely so I thought I would post up some information to help get it started! I have a LOT of experience with casting resin and have been casting for 6 or 7 years now. I have mixed and poured over 300 gallons in my casting "career" I have cast everything from "worthless Wood" to dog hair. Heck, I even cast some cat crap one time for a gag gift! I have played with most all of the different casting resin out there and my preference, by FAR, is Alumilite urethane resin.
When I was developing my cactus blanks, I started out using polyester resin. I absolutely hated the smell and the way it stunk up my shop for days. I also hated the brittleness and the long time it takes to set up so I started looking for something else. I ran across a company called Alumilite and posted some questions on their forum. The owner of the company, Mike Faupel personally answered my questions and offered me some samples to try out. I loved it! It has virtually no smell and sets up real quick, typically less than 20 minutes! After working with Mike for a few years, I went to him with an idea for the "perfect turning resin". I had 3 issues I wanted him to address with Alumilite Water Clear: 1) polishability-it does not polish up as easily as PR, 2) Open time- it only has a 5 minute open time, and 3) cost. Mike was real interested and said he could work on the first 2 but could not do much on the price. A few days later, I received some test resin via Fedex and started testing. After 6 or 7 different formulations and giving feedback to Mike, Alumilite Clear was "born". I can get just as good of a shine with it as I can PR and it has a 7 minute open time, plenty of time to mix and pour. It is still more expensive than PR but the benefits of no smell, quick turn around time, and WAY less brittle make it my choice of casting resins.
Fist, let me state specifically and to the point, I do not work for, nor get paid by Alumilite in any way. I am just a very happy customer that has had the privilege of working closely with Mike Faupel, the owner, over the last 6 or 7 years. I thought I would state thins since I just did some videos for them and don't want anyone to think I am on their payroll somehow!
With that out of the way, I thought I would list the various formulations of Alumilite and a little about them. I have used every one of their casting resins over the years and since I see the question frequently of which one to use, I thought this might be helpful to someone. I will focus only on the resins commonly used in blank casting.
Alumilte is a 2 part urethane casting resin. It uses equal parts of A and B by weight. Complete and thorough mixing as well as accurate measurement is required for best results.
First, some definitions:
pot Life: This is the amount of time you have to get the resin poured into the mold and under pressure. It begins sometime after you have started mixing the 2 parts
Viscosity: The "thickness" of the resin. The lower the number, the thinner the resin. Compare this with the CA that you use as they both are rated in Centipoise (cps)
Demold Time: The amount of time you need to let it "cure" before removing it from the mold
Shore D: The hardness of the cured resin. This is measured with a durometer and uses the Shore D scale. The higher the number, the harder the resin.
Elongation: This is the amount of "stretch" the cured resin has before it breaks. It is an indication of the brittleness of the resin for turning and indicates how chippy it will be. Lower elongation equals more chippy and likely to blowout.
Temperature Resistance: The temperature where the cured resin will deform. This is important when sanding.
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-CLEAR RESINS-
Good for clear casting or casting where you want translucent swirls and depth of colors. Requires pressure or vacuum to get rid of bubbles.
Alumilite Water Clear
Their original clear casting formulation, thinner and less brittle than Alumilite Clear but does not polish up nearly as well. It also sets quicker and has a higher temperature resistance.
pot Life: 5 Minutes
Viscosity: 400 CPS
Demold Time: 30-60 minutes
Shore D: 80
Shrinkage: .5 %
Elongation: 9%
Temperature Resistance: 155° F
Alumilite Clear (Formerly Alumilite Crystal Clear)
This is a formulation I helped developed for the benefit of turners. It polishes better than Water Clear but is more brittle but still WAY less brittle than PR, however. It also has a longer open time and is the preferred resin for turning.
pot Life: 7 Minutes
Viscosity: 450 CPS
Demold Time: 45-90 minutes
Shore D: 80
Shrinkage: .5%
Elongation: 8%
Temperature Resistance: 140° F
Amazing Clear Cast
This is an epoxy casting resin and is NOT advised for turning. It is real slow set and is more useful as a bartop finish or where you need a really slow setting resin.
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-OBSCURE RESINS-
Good for solid color or multi- solid color blanks. Does not give any significant effect when using metallic powders. Does not require pressure or vacuum.
Alumilite Regular
This is Alumilite's original casting resin. It is available in light tan or black. It is also the fastest setting Alumilite and does not have a lot of use for turning. It is the most resistant to temperature, however.
pot Life: 90 seconds
Viscosity: 190 CPS
Demold Time: 5-8 minutes
Shore D: 75
Shrinkage: .5%
Elongation: 7%
Temperature Resistance: 250° F
Alumilite White
This is Alumilite's thinnest resin but is also their softest. it is good for making multi colored blanks
pot Life: 2.5 Minutes
Viscosity: 90 CPS
Demold Time: 5-15 minutes
Shore D: 72
Shrinkage: .4%
Elongation: 10%
Temperature Resistance: 140° F
Alumilite RC-3
This is a good value resin. It is the cheapest of Alumilite's casting resins but is only available in gallons kits. It comes in light tan or black and has a high temp resistance.
pot Life: 3 Minutes
Viscosity: 110 CPS
Demold Time: 5-15 minutes
Shore D: 74
Shrinkage: .4%
Elongation: 12%
Temperature Resistance: 190° F
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Here is some info on Polyester Resin for comparison sake:
pot Life: 30 Minutes?
Viscosity: 450 CPS
Shore D: 78
Shrinkage: 4%
Elongation: 1.5%
Temperature Resistance: 160° F
Odor: VERY HIGH!
Hope this information helps someone!