EZ~Mix® 40 Brushable Urethane Rubber: The Easiest To Mix Off All "Off-The-Shelf" Brush-On Systems
New EZ~Mix® 40 brushable urethane rubber is a liquid / liquid system. Parts A and B are very low in viscosity, making it easy to measure 1A:1B by volume and the easiest to mix of all brush-on systems (perfect for novice mold makers).
It has a good working time of 18 minutes (at room temperature) and a re-coat time of about 60 minutes. If you want to thicken the rubber to make a cut shim, you can use Cab-O-Sil or similar fillers.
Unlike Rebound 25, you can apply EZ~Mix® 40 to a sulfur clay model (model must be sealed with Spray Shellac, followed by a release agent).
Beware of "mass" with this product - Unlike the other brushable rubbers, this product has a slight exotherm to it and is mass sensitive. That means that large amounts in a mixing container will gel more quickly. Also, the working time for this product will be drastically reduced in warm environments.
EZ~Mix® 40's tear strength is better than competitive products on the market. But like these competitive products, cured rubber will "unzip" if a notch tear develops in the rubber. Brush-On® 40, 50 and 60 have much better overall tear strength.
The secret for success in using this or any brush-on rubber is to apply a thin first layer (detail coat) to minimize air entrapment and capture all detail from the model's surface.