EZ ~ Mix® 40 Urethane - The Easiest To Mix Of All!
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.
1 - The original model is made of urethane plastic. It is hot glued to a working surface.
2 - The model and board are sprayed with a coating of Ease Release® 200 release agent.
3 - EZ ~ Mix® 40 Parts A and B are measured in equal amounts by volume.
4 - Wearing rubber gloves is recommended.
5 - Parts A and B are combined in a mixing cup. So-Strong Red color tint is added to color the rubber. This will ensure thorough coverage over the white model.
6 - Begin brushing the EZ~Mix® 40 onto at top of the model and work your way down.
7 - The first layer is applied thinly to ensure capture all detail. A 3 in (7.6 cm) flange is created.
8 - After 1 hour, the rubber is tacky. A second batch of rubber is mixed and applied (untinted).
9 - After the 2nd layer is 'tacky', Parts A and B are mixed with Cab-O-Sil to thicken the rubber.
10 - The thickened rubber can be used to create a 'cut shim' and fill in undercuts.
11 - So-Strong color tint is added to provide contrast to the cut seam.
12 - The cut seam is applied along an edge to minimize and seam that may be reflected in finished castings.
13 - The cut shim is extended to the outer edge of the flange.
14 - Parts A
15 - Another batch of Cab-O-Sil rubber is mixed and used to further build up the cut shim.
16 - A 4th (final coat) of untinted EZ~Mix® 40 is applied. All layers are then allowed to cure for at least 16 hours.
17 - After the rubber is fully cured, the flange is trimmed to help the mold register with the support shell.
18 - Clay is used to form parting shim, dividing the support shell into two halves.
19 - Aluminum foil is placed over the mold and clay shim so the Plasti-Paste® shell won’t adhere.
20 - Plasti-Paste® plastic is mixed and applied over the first half of the model. Allow 1st half of shell to cure for 90 minutes.
21 - After 1st half of shell is cured, the clay shim is removed. Foil is used to cover the 2nd half of the rubber mold and cured Plasti-Paste® to prevent adhesion.
22 - Plasti-Paste® is mixed (green pigment added) and applied forming the 2nd half of the shell.
23 - When the 2nd half of the shell has cured, both halves are removed from the rubber mold.
24 - An exacto knife is used to cut through the thickened shim for easy removal of the rubber.
25 - The EZ~Mix® 40 mold rubber has perfectly captured all detail from the model.
26 - The supprt shell and mold are reassembled and placed into a bucket for stability during casting. Make sure everything is level.
27 - EZ~Mix® 40 is a urethane rubber and requires a release agent to stop the plastic from sticking.
28 - Tinted Smooth-Cast® 300 is poured into the mold. The plastic cures quickly: demold in 15 minutes.
29 - The result is a perfect reproduction, with a mold and support
shell that can be used repeatedly.