Here at Silicone and Epoxy Technology we are trying to keep up with the times, and it seems that this time people are looking for fumed-silica! We also know that most people like to do one stop shopping vs going from website to website and hopefully this will be you place to go!
We are a distributor for many companies Smooth-on being one of them, and they happen to carry fumed-silica. They call it UreFil 9, and we have it available you you!
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What exactly is UreFil 9 -it is a fumed-silica based thickening agent primarily used with liquid urethane and silicone rubbers for brush on mold making applications. URE-FIL® 9 is added in small amounts to the mixed rubber until the desired viscosity is achieved. URE-FIL® 9 can also be added to liquid urethane resins to create casting effects and to thicken the material for trowelable casting applications.
There are a few other UreFil fillers that you can choose from i will list them here as well as what they are used for:
URE-FIL 3 - ceramic filler which is added to urethane resins and castable epoxies to reduce cost. This filler is speckled grey in color and can give castings a stone-like finish. Recommended starting mix ratio is 1A to 1B to 1 part URE-FIL 3.
• URE-FIL 5 is your best choice for creating a wood grain effect. Note: your mold must reflect the wood grain pattern of the original model. Mix 1 part filler with 1A:1B of Smooth-Cast® 320 resin and cast into mold. After demold, apply wood stain or shoe polish to casting surface to bring out wood grain effect.
• URE-FIL7 mixes well with urethane resins and castable epoxies and will improve dimensional stability (reduce the shrinkage rate of some resins, for example). It is also often added to materials to make them flame-resistant. URE-FIL 7 can be mixed with Smooth-Cast 325 and SO-Strong color tints to create marble effects. The maximum amount that you can add to a resin before compromising the physical properties of the cured plastic would be 1A:1B to 2 parts filler. A mix ratio of 1A:1B to 3 parts filler will make the plastic trowelable, but the cured plastic will also be brittle.
• URE-FIL 11 is a fiber-based filler that can be added to Smooth-On urethane and silicone rubbers, urethane plastics and epoxies to thicken for brush-on applications. URE-FIL® 11 can be used with all Smooth-On silicones, including those which do not respond to THI-VEX® such as Ecoflex® 00-30 and Mold Max 40.
• URE-FIL 15 - micro-balloons that can be added to Smooth-On urethane plastics and epoxies to create very light weight castings. Castings which float on water can be created by using proper proportions of URE-FIL 15. A casting resin filled with a large proportion of URE-FIL 15 can be described as a ‘syntactic foam’ . Syntactic foams are non-expanding foams which are stiffer, stronger and more water resistant than water-blown expanding urethane foams of the same density.
Credit to Smooth on for photos and TDS info