Mold Making Systems
Food Grade (R-2138 SP A/B)
R-2138 SP A/B is a two-part, Platinum Based Silicone RTV rubber designed for making molds in food grade applications. This system’s low viscosity allows for easier mixing and de-airing while providing high tear strength and elongation properties. This RTV has been tested to meet Title 21(food and drug) Code of Federal Regulations (CFR), section 177.2600, Rubber Articles intended for repeated use.
***For a copy of the CFR, go to: www.access.gpo.gov/nara/cfr-table-search.html
Physical Properties (Typical Values):
Uncured Compound:
Color: Tan Base Purple Catalyst
Viscosity: 25,000 cps
Mix Ratio: 100 A/10 B By Weight
Shelf Life: 6 months
Cured Compounds (24 Hours @ 77F (25C)):
Specific Gravity: 1.25
Durometer: 42A
Tensile Strength (PSI): 750
Tear Strength (PSI): 125
Elongation, %: 350
Mixing Instructions ** (SCALE Measurement Required)
Mix 10 parts base to 1 part-curing agent by weight. Automatic mixing equipment or manual mixing may be used to combine base and curing agent. Immediately after mixing, place the material in a vacuum chamber to remove trapped air. As the vacuum is drawn, the materials will expand as much as four times it’s original volume. Remove from vacuum chamber and pour very gently, so as not to incorporate air back into the material. Cure can be accelerated with mild heat, 150f @ 1 hour per inch thick. Note: This product was designed for high knotty tear and low viscosity, and off ratios will create a rubber with poor cured properties---mix range is 9.5 to 10.5 %.
Inhibition:
Certain materials will cause inhibition or neutralizing of the curing agent. These materials are sulpher and organo-metallic salt containing compounds found in organic rubbers and many condensation cure RTV, chloride solvents – aimnes. Avoid using latex gloves, oil based clays and Tin/Condensation cured RTV’s. Inhibition may easily be determined by brushing a small quantity of this material over the surface and allowing it to cure. If material remains tacky and gummy after the curing time, then the part’s surface is acting as an inhibitor. **See Addition Cure Technical Data Sheet for inhibiting materials
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.