Description
This mold rubber is known for its abrasion resistance and high tear strength.
Brush-On™ 35 features a 1:1 mix ratio by volume and can be easily applied with a brush or spatula.
- Can be applied onto vertical surfaces without sagging
- Cures with negligible shrinkage
- Captures exact detail from any original model
- Soft and flexible, suitable for models with deep undercuts
- Can be inverted for glove molds
- For commercial/industrial use only
Technical Properties
- Mix Ratio by Volume: 1A:1B
- Mix Ratio by Weight: 3A:2B
- Working time: 20 minutes
- Cure Time: 16 hours
- Shore Hardness: 35 A
- Color: Grey-Green
- Specific Gravity: 1.29 g/cc
- Specific Volume: 0.78 cm³/g
- Tensile Strength: 2.31 MPa
- Elongation @ Break: 1,000%
- Die C Tear Strength: 10.0 kN/m
Instructions
Materials should be stored and used at room temperature (23°C). Ensure low humidity. Wear safety glasses, long sleeves, and rubber gloves. Good ventilation is necessary.
Sealing and Release Agents
Porous materials must be sealed before applying a release agent. Use SuperSeal™ or One Step™ for sealing without affecting surface detail. Non-porous surfaces require only a release agent.
N.B. Under certain circumstances, shellac can be used as a sealer, but special care should be taken with subsequent application of a release agent, since shellac acts as a bonding agent for Polyurethanes.
Apply a release agent to facilitate demolding. Brush the release agent with a soft brush over all surfaces, then apply a light mist coating and let it dry for 30 minutes. Conduct a small test application to be safe.
Mixing
Liquid urethanes are moisture sensitive. Use clean metal, glass, or plastic containers. Mix Part A (paste) and Part B (liquid) thoroughly for 3 minutes, scraping the sides and bottom of the container.
Do not mix more rubber at a time than can easily be applied in ca. 10-15 minutes. Mixing by weight (3A:2B) generally yields better results than mixing by volume.
Application
Apply in layers. Four to six layers are suitable for a working mold. Using an indication color between subsequent layers helps to build an even mold thickness. Use a stiff brush for the first coat to capture detail. Let each coat dry for 30-40 minutes before adding the next. Do not allow rubber to fully cure between layers to avoid delamination.
Curing
Allow rubber to cure overnight (at least 16 hours) at room temperature. Cure time can be reduced with mild heat or by adding a cure accelerator. Do not cure below 18°C.
Post Curing
To enhance properties, heat the rubber to 65°C for 4 to 8 hours after curing.
Support Shell
A rigid support shell is needed to support the mold during casting. Use burlap reinforced plaster or Plasti-Paste™ as a mother mold material.
Using The Mold
Apply a release agent to the mold before each casting. The type of release agent depends on the material being cast. For gypsum plaster, sponge the mold with a soap solution for better flow and release.
Performance & Storage
Fully cured molds are durable. Clean with a soap solution and dry before storing. Store molds on a level surface in a cool, dry environment. Do not stack molds or expose them to moisture or UV light.
Safety and Handling
Shelf life is reduced after opening. Use the remaining product as soon as possible. Replace lids immediately after dispensing. Remains of part B (liquid) can be kept in a small(er) container, to minimize air exposure, or use XTEND-IT™ Dry Gas Blanket to prolong shelf life.
