I have created a table listing all the mold materials that I can find - Natural Rubber, Silicone Rubber, Room Temperature Vulcanizing Rubber. These are materials that every mold maker uses and needs. You can download the Excel spreadsheet here. Once you have the spread sheet you can sort the different products to compare qualities. I shall refine spreadsheet over time to make it more useful. Try it now to choose a mold compound for your specific job!
Search the spread sheet for hardness and you’ll see which products have the highest durometer.
Sort the spread sheet for tear strength and you’ll see which products resists tearing the best.
Imagine that you have an RP resin that you want to mold but it’s made with a castable resin like Rio Grande's DC-500.
Ideally, for a mold, the RP master would have been grown using DM-220 with it’s ceramic nano-crystals to withstand molding in heat cured silicone rubber. But you have a master in DC-500 that is meant to burn out cleanly. It has a low melting point, less than 200 degrees F! Imagine that you need several waxes by the end of the day but your CAD operator is committed to another job. You need a mold of that design right now so you can get 10 waxes into today’s cast.
Sort through the ‘Cure Temperature’ column to find mold compounds that cure below the melting temperature of DC-500. Several RTV compounds appear as ideal candidates. Spray the DC-500 with a teflon release agent and mold away. Your waxes are ready in about 2 hours.
I invite everyone in the jewelry world to submit mold compounds to add to the chart. Who makes the most versatile, useful mold compounds? I'll post them in the comparison chart and let you decide.