Casting urethane is a white, opaque, fast curing resin. Mix equal parts (1:1) by weight. Part A weighs a little more than part B, that's why the levels look different. Urethane resin is still tin-table with our resin tints, but will cure to a pastel color. Working time varies from 3-7 minutes. (The more you mix, the faster it will cure) Works excellent in Silicone RTV molds as well as many other flexible mold materials. It is recommended that you use mold release when casting.
Polyol and Isocyanate
Work fast. Silcast sets up in about 5 minutes. (from the time part A touches part B)
The resin will go from a clear to a milky white when it is curing.
Make sure your mold is air-tight.(use kleen/klean clay to seal leaks
wait at least 45 minutes before de-molding your casting.
Urethane resin, like most casting resins, will generate heat while it's curing. It may get too hot to touch. Make sure you are casting in an area suitable for hot temperatures.
The warmer the temperature, and the more dry the air...the FASTER your resin will cure.
humidity also affects casting time, if it's raining... its NOT a good idea to cast that day. here's why: This urethane is highly sensitive to water. if there is water in your mold, or over 90% humidity, the resin will foam up. This is also useful information, because you can make your casting resin into casting foam by adding water. The foam will have a hard, bubbly appearance. The foam has no flexibility. Experiment with ratios until you find the one best for your project. (it only takes a few drops of water)
This casting urethane has a shrinkage rate of >1%.
To avoid air bubbles, lightly bounce the mold several times within the first 1-2 minutes of pouring.
If you spill some of this stuff, the best way to remove it is to let it completely cure, then come back and tap it off with a chisel/flat-head screwdriver. The nature of the resin is that it only wants to stick to itself, thus making it an ideal material for casting. Chances are, if it has landed on a non-porous surface, i.e.concrete, glass, finished wood, etc. its going to come off easily when its dried. If it gets on your clothes however, you're going to have to live with it... forever. If the resin soaks into a material it's never coming out. Put down newspaper or plastic before you pour.
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