Description
This platinum-cure silicone rubber self-thickens for creating brush-on molds of various models.
Rebound™ 40 mixes 1A:1B by volume and can be applied to vertical surfaces without sagging. It cures with negligible shrinkage to a flexible rubber.
Features
- Hard and not very flexible
- Compatible with Rebound™ 25 for layered application
- Non-stick to most surfaces, reducing surface preparation
- Easy mixing of two liquids
- Durable for production casting of resins and low-temperature metal alloys
- Long library life
- Four thin layers create a strong, durable mold for casting wax, gypsum, concrete, or resins
- Applications include sculpture reproduction, architectural restoration, and candle molds
- Not compatible with sulfur-containing modeling clays
Technical Properties
- Mix Ratio By Volume: 1A:1B
- Mix Ratio By Weight: 1A:1B
- Working time: 20 minutes
- Cure Time: 6 hours
- Shore Hardness: 40 A
- Specific Gravity: 1.14 g/cc
- Specific Volume: 0.88 cm³/g
- Color: Green
- Tensile Strength: 3.35 MPa
- Elongation @ Break: 324%
- Die B Tear Strength: 18.6 kN/m
Instructions
Safety
Use in a well-ventilated area. Wear safety glasses, long sleeves, and rubber gloves. Use vinyl gloves only, as latex gloves inhibit curing.
Storage
Store and use at room temperature (23°C). Warmer temperatures reduce working and shelf life.
Cure Inhibition
Inhibition may occur with contaminants like latex, tin-cure silicone, sulfur clays, and certain wood surfaces. Test compatibility on a non-critical area.
Seal the object with a clear acrylic lacquer to prevent inhibition. Allow the sealer to dry before applying the rubber.
When in doubt, a small test application to determine suitability for your project is recommended.
When working with modeling clays that contain heavy amounts of sulfur, even a sealer will not suffice. Do a small scale test for compatibility before starting your project.
Applying A Release Agent
The use of a release agent is usually not necessary, but will help with the ease of demolding. Use Ease Release™ 200. Spray the object once, then brush lightly over the surface, spry once more lightly and let dry for 30 minutes.
Test on an identical surface if unsure.
Measuring & Mixing
Pre-mix Part A and Part B separately. Mix thoroughly after dispensing required amounts into a container (1A:1B by volume or weight), ensuring a uniform color with no streaks.
Applying The Rubber
Apply in layers. Use a stiff brush for the first thin layer to capture detail. Let dry until tacky before adding layers. Use mild heat to reduce tack-time.
Coverage
Coverage: 1 gallon = 0.65 sq.m, 5 gallons = 3.25 sq.m.
Additives
- Add different Silc-Pig™ color pigment to successive layers, to distinguish them.
- Thi-Vex™ thickener can be added to increase the thixotropy.
- Add Smooth-On Silicone Thinner™ to lower the viscosity of the initial mix.
Apply A Support Shell
Once fully cured, a rigid support shell is necessary. PlastiPaste™ II is ideal for this purpose.
Curing
Allow the mold to cure for at least 6 hours at room temperature before demolding. Do not cure rubber at temperatures below 18°C. Cure faster by applying mild heat (60°C) for 2 hours.
Using The Mold
When casting wax or gypsum, the use of a release agent is not necessary.
Apply a release agent like Ease Release™ 200 when casting polyurethane, polyester, and epoxy resins to prevent mold degradation.
Mold Performance & Storage
The physical life of the mold depends on it's usage. Casting abrasive materials can erode mold detail. Clean molds with a soap solution and dry before storing on a level surface in a cool, dry environment.
