Urethane RTV Rubber
Brush-On System (RU-435 TH)
RU-435 TH A/B Two-Component, 100% solids Urethane Elastomer RTV that becomes thixotropic within minutes for creating thin, brush-on bladder molds within hours. Once cured, this urethane RTV provides a strong, durable mold with phenomenal tear strength. Use to create thin, flexible molds for easier de-molding or use to cut mold cost through minimizing material usage. Applications include mold making for the art, architectural, and foundry industries. Note: A Mother Mold, usually made of CastShell Plaster, Fiberglass SLR-22 or Trowel-On 60 (Thixo-tropic plastic), is used to help support the thin bladder mold.
Typical Physcial Propertities:
(For Components) Component A Component B
Viscosity (cps): 1000 1000
Mixed A/B: 450,000
Mix Ratio, by Weight or Volume: 100 100
Color: Yellow/Clear Gray
(For Cured Material)
Shore A hardness: 35
Tensile Strength (psi): 406
Elongation %: 695
Tear resistance (psi): 85
Reactivity Data:
Gel Time: 15 – 20 minutes
Recoat Time: 30 – 60 minutes
De-Mold Time: 3-4 hours
Full Cure: Next Day
**Samples tested 100 gram mass. Gel time and cure will vary on various size mixes and hotter summer weather will create quicker gels & cures.
Preparation of Master
Urethane elastomers will adhere to most surfaces. A proper mold release must be used on all surfaces-- MR-150 or ER-2300 is recommended. Wood, plaster, stone, pottery, masonry, or any porous surface must be sealed with lacquer or clear shellac prior to applying release. Partall Film #10 or shellac is suitable for sulfur & water based clays. Allow 24 hours to dry before preparing master with mold release. Urethane RTV cures to a flexible rubber in above cure times. These products are safe to use as directed, check MSDS for safety information.
Mixing Instructions:
Mix A & B components by proper weight or volume, taking care not to whip excess air into mixture. A quick vacuum opening and closing exhaust valve will press out some air. Prepare master with a proper release agent, ER-2300 or MR-150, then apply a thin surface coat of RU 435th to capture the detail on the first coat. Light air pressure (hair dryer) can be used to work out air bubbles on surface. Mix only the amount of material needed over a 10-minute application. Many small batches can be mixed and applied as long as you are adding to a sticky surface—within 30-60 minutes. A mold can be built-up in 3-4 coats. Reinforcing with fabric can be applied in areas that may rip and tear, usually along the edge of a mold—avoid reinforcing those areas where the rubber mold needs to be stretched. Please do not hesitate to call for further information.
Using Mold
The use of a release aids demolding and is recommended prior to each casting. Release selection is based on material that is to be cast. R-100-50 Release is recommended for casting concrete. No release necessary for wax or plaster products.
Storage
Un-mixed material should be stored in warm, dry area with lids secured tightly. Once containers are opened, material should be used in a short time period. Pre-test any aged material before using. Molds or parts should be cleaned with a soap solution and completely dried prior to storing them in a dry, cool environment. Avoid stacking or exposing them to environmental elements—UV and moisture.
The information and data contained herein are based on information we believe reliable. Each user of the material should thoroughly test any application and independently conclude satisfactory performance before commercializing. Suggestions of uses should not be taken as inducements to infringe on any particular patent.