Cabosil or fumed silica is used to thicken the epoxy to prevent sagging. In kayak building it is used mostly for making fillets or gluing. It is not clear in epoxy. It should not be used where sanding is required. It is hard as a rock when cured. I prefer using chopped fiber to thicken epoxy for gluing because it sands easier and West Systems in their technical data says chopped fibers makes the best glue joints. Fumed silica makes a smoother fillet than chopped fiber. Raka is great. Its advantages are it is thin so it penetrates wood well and wets out fabric well, it has good working time with the slow hardener, has no color and it costs less. Its disadvantage is it's thin and it takes more fill coats. I like it and with its cost advantage I plan to keep using it.

: looking to pick up glass & epoxy have a couple of ? I've used both mas.
: & west system with good results.
: 1.was thinking of using raka this time (cheaper)
: 2.have used wood flour as a thickner but need a clear finish.will carbosil
: work?
: any comments would help.
: thanks