Injection Molders are on a constant quest to reduce cycle time that results in savings of time and money. As a rule of thumb; injection molding cycle times comprise 5% injection, 80% cooling, and 15% ejection. Normally, cooling time is the only phase of the injection molding cycle where cycle time can be reduced. Interestingly, large reductions in cooling time could have an unwanted effect on the dimensions of the part. Nan-O-Sil ASD is a high purity, amorphous, colloidal silica in the form of a white powder. The spherical particles range from 0.02 to 0.55 microns (20 to 550 nanometers). A study was conducted, where the temperature of the parts as well as warpage was measured to determine how well the ASD additive could reduce cooling time. Several materials were run at the same cooling time to evaluate different combinations of materials. The semi-crystaline materials were Polypropylene (PP), Polybutylene Terephthalate (PBT), Nylon 6/6, and High Density Polyethylene (HDPE). The only amorphous material was Acrylonitrile Butadiene Styrene (ABS). An infrared camera was used to measure the part’s temperature at each run. Nan-O-Sil ASD, can reduce injection molding cycle times by 20% to 30 % in PP, nylon, PBT, and ABS; in 16 and 32 cavity molds along with other benefits such as reduced flow lines, improved color dispersion, and improved dimensional stability of PP, nylon and various glass-filled polyamides and other engineering plastics. The reduction in cooling time in PP is 77%, 70% with glass-filled PBT and 67% with Glass-filled Nylon. ABS shows no reduction in cooling time. The most likely cause of the reduction may be because the Nan-O-Sil ASD acts like a nucleating agent. The Nan-O-Sil ASD may also inhibit polymer chain movement, just like filler. New laboratory test results from Rheo-Plast indicate that the benefits previously demonstrated also extend to other engineering resins. The compounded pellet concentrates with a wax or a desired resin as the carrier is also new. Up to now, the colloidal silica has been supplied as a white powder with spherical particles of 0.02 to 0.55 microns (20 to 550 nanometers). Addition of just 0.8% silica shortened injection molding cycle times for tensile test bars by 22% to 31% for unfilled acetal copolymer, PPS, and PEEK, as well as 33% glass-filled PC. Mechanical properties were generally maintained or improved. Although the data are not shown, Rheo-Plast also found that Nan-O-Sil ASD reduced cycle times by 5% with Noryl PS/PPO blend and 27% with HDPE. In addition to the new pellet concentrates, the additive can be added in pure powder form at the processing machine - tumble blends the additive with resin for 15 min before molding. No dusting is required because the silica tends to stick to the pellets. Another method is to use a feeder at the machine throat to meter the silica in proportion to the resin. In addition, users of liquid colors or additives can mix the silica with the liquid prior to molding.