Smooth-On URE-FIL™ fillers disperse easily in Smooth-On materials. They can be added to materials in different proportions to achieve a variety of working properties and effects. Some fillers are designed for cost-savings, others are designed for specific casting effects or improved physical properties. Other URE-FIL™ fillers are designed specifically for thickening materials for brush-on or trowelable application.

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.