Kicker does not make ca set any harder or more brittle than not using it at all. It does however compromise the inherent strength of the glue if more than what it takes to initilize the curing is used. As far as harder to sand, you should never use ca in a place where sanding will be needed if at all possible. If you use wood type glues, which I still do in certain applications, always look for the sandable type as all alpahtic wood glues are not the same.