Description
This polyurethane rubber is designed for use with the EZ~Spray™ Junior Cartridge System, suitable for spraying onto vertical surfaces to create molds or for quickly making molds of large surface areas. Once a suitable thickness is achieved, it cures overnight with negligible shrinkage, resulting in a durable mold rubber. A support shell can be applied by spraying plastic over the fully cured rubber mold. It is suitable for casting materials such as wax, gypsum, urethane resins, epoxy resins, and concrete.
Technical Properties
- Mix Ratio By Volume: 1A:1B
- Pot Life: 20 minutes
- Thin Film Recoat Time: 10 minutes
- Cure Time: 16 hours
- Shore Hardness: 45 A
- Specific Gravity: 1.025 g/cc
- Specific Volume: 0.98 cm³/g
- Color: Light Blue
- Tensile Strength: 3.52 MPa (510 psi)
- Elongation @ Break: 375%
- Die C Tear Strength: 17.5 kN/m (100 pli)
- Shrinkage: Negligible
- Mixed Viscosity: Sprayable
Use Cases
Used for making molds of large surface areas, casting a variety of materials, and creating durable mold rubbers for industrial applications.
Instructions
Safety
Store and use at room temperature (23°C/73°F). These products have a limited shelf life and should be used as soon as possible. Environmental humidity should be as low as possible. Good room size ventilation is essential. Wear safety glasses, long sleeves, and rubber gloves to minimize contamination risk. Spraying should be done in a well-ventilated area. Breathing protection: Everyone in the spray area should wear an independent air supplied hood or NIOSH approved breathing mask.
Do Not Attempt To Spray Rubber Or Plastic Without First Reading The Manual!
Applying A Sealer / Release Agent
To prevent adhesion between the rubber and model surface, models made of porous materials (gypsum plasters, concrete, wood, stone, etc.) must be sealed prior to applying a release agent. Superseal™ is a fast drying sealer suitable for sealing porous surfaces without interfering with surface detail. Shellac is suitable for rough contours and modeling clays that contain sulfur or moisture (water based). Non-Porous models made of metal, glass, acrylic, PVC, other hard plastics, and sulfur-free clays require only a release agent which should be allowed to dry before applying the rubber.
In all cases, the sealing agent should be applied and allowed to completely dry prior to applying a release agent. Polyurethanes are adhesive. A release agent is required to facilitate demolding. You can purchase a suitable release agent (Universal™ Mold Release) from a distributor.
IMPORTANT: Apply release agent to all surfaces that will contact the rubber. To ensure thorough coverage, lightly brush the release agent with a soft brush over all surfaces of the model. Follow with a light mist coating and let the release agent dry for 15 minutes.
Because no two applications are quite the same, a small test application to determine suitability for your project is recommended if performance of this material is in question.
Applying The Rubber
This product must be sprayed in layers. Generally, 4 layers (minimum 1 cm or 3/8”-1/2” thickness) is suitable for a working mold. The first layer, the detail coat, is a thin layer to capture model detail. Subsequent coats will add strength to the mold. Spray undercuts and recesses first. Let the first coat dry for 10 minutes at room temperature or when it becomes “tacky” before adding the next coat. Repeat until the necessary thickness is achieved. Do not allow rubber to fully cure between layers, as delaminating may result.
Curing
Allow the mold to cure overnight (at least 16 hours) at room temperature (23°C/73°F) before demolding. Do not cure rubber where temperature is less than 18°C/65°F. Post curing the rubber after it has cured at room temperature (applying heat – 65°C/150°F for 4 – 6 hours) will increase physical properties and performance significantly.
Apply Support Shell
After all layers of rubber fully cure (overnight) a support shell should be applied over the rubber mold. This will prevent the mold from distorting when casting into it. Use plastic to apply on a hard, durable and lightweight plastic shell.
Using The Mold
A release agent facilitates demolding and should be applied to the mold before each casting. The type of release agent to use depends on the material being cast. Universal Mold Release is good for releasing resins recommended for most applications and is available from a distributor. The mold should be sprayed with the release agent, brushed over all surface areas and allowed to dry before casting. To ensure thorough coverage, lightly brush the release agent with a soft brush over all surfaces of the model (especially areas of intricate detail). Apply a second thin mist coating and let dry for 15 minutes casting.
Mold Performance & Storage
Fully cured molds are tough, durable and will perform if properly used and stored. The physical life of the mold depends on how you use it (materials cast, frequency, etc.). Casting abrasive materials such as concrete will eventually erode mold detail, while casting non-abrasive materials (wax) will not affect mold detail. Using the right release agent is essential in all cases. Before storing, the mold should be cleaned with a soap solution and wiped fully dry. Two part (or more) molds should be assembled. Molds should be stored on a level surface in a cool, dry environment. Do not stack molds, expose them to moisture or UV light.
