en the mixture. The "manual " that comes with the system three recommends using cabosil. I tried it without, using a tremendous amount of micro-balloons and it wouldn't stiffen up. It is my understanding that the mico-balloons makes the epoxy lighter and sandable and the cabosil makes it stiffer. Tom
Cabosil will work but to me it doesn't sand very well. Micro-balloons will definitely thicken the mixture and prevent it from running. You just aren't adding enough. It's astounding how much microballoons can be added to a small amount of epoxy. You can get it as thick as peanut butter if you want to (great dent filler!).