Urethane RTV Rubber
RU-240 (40A Shore)
RU-240 A/B Two-Part, Urethane Elastomer RTV mold rubber best suited for casting plaster, wax and silicone rubber parts. Cement can be casted, but it will slowly erode and deteriorate mold, eventually leave a white haze on casted parts--Use RU-400 Series Molding Urethane RTVs
Physical Properties:
Color (mixed): Tan
Mix Ratio: 100 B /10 A
Mix Viscosity: 4,000 cps
Shrinkage: nil
Hardness: 40 shore A
Coverage: 20 cubic inches per pound
Preparation of Masters:
RU-240 may exhibit cure inhibition with certain surfaces that have been contaminated. In any case where the user's results may be questionable, a pre-test of the process should be performed to prevent any damage to the master or mold and to prevent any loss of labor time.
Wood, plaster, stone, pottery and masonry must be sealed with potters’ soap or clear shellac. Since clear shellac is also used to bond RU-240 to some surfaces, a release agent must be used in conjunction
(MR-150).
Non-porous surfaces may be coated with a release agent such as Lift or polyester Para film. Some plastics and lacquer coatings may be softened by RU-240. These surfaces should be coated with PVA (Polyvinyl Alcohol) and allowed to dry for 24 hours.
Mixing and Curing:
Mix in proper ratio of 100% "B" to 10% "A" with a mixer, scraping sides and corners several times. Avoid allowing air into mixture. For large mixes, 4 gals or more, use a Jiffy mixer with a drill motor work well. Do not use wood or paper type mixers that may contain moisture and create bubbles in cured rubber. Pre-mix both components prior to mixing. Use a clean, dry container and allow 2-3 times the volume of the starting material to be available for expansion when de-airing the mixture.
RU-240 cures in 16 hours at 77F and is ready to be de-molded at that time. The cure will be finalized in 72 hours. Curing in a warmer, dry environment at temperatures from 77F to 140F will greatly accelerate the curing process, therefore, decreasing the pot life - while temperatures below 77F will slow down the cure time and increase the pot time. Avoid conditions below 60F during cure time. First time users should pre-mix small test samples to determine workability of the product.
STORAGE:
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. Store molds in cool, dry area, out of direct sunlight.
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