Cab O Sil, 32 fl. oz., Quart Container
Cab-o-sil, also know as Aerosil, colloidial silica, or silicone dioxide, is a common inert filler. It is a fumed silica that when introduced into fluids, such as resin, acts as a thickening agent.
Use to add thix properties to resins, to thicken a resin to a desired consistency, or to make putties.
For fairing putties use 3M bubbles or Phenolic Microballoons then add just enough cabosil to get the desired properties. Putties made from resin and cabosil alone are difficult to sand.