: Hi folks,
: has somebody tried talkum powder as a thickening agent in epoxi.
Joaquin,
Talc is a mineral, magnesium silicate, the powder is ground talc. For personal use, such as baby powder, a perfume and/or an antiseptic may be added. "Bondo" an autobody filler known to anyone from the rustbelt states was originally formulated by mixing raw talc powder with polyester resin. The talc both thickened the resin and aided in surfacing the patch. With an artful application of Bondo and paint the worst rust bucket could be made to look pretty good, for a while. The problem with Bondo is that the resin was not moisture proof and the talc loved to absorb moisture. This resulted in new rust forming under the patches and popping them off the auto body.

Moisture should not be a problem with epoxy, but I wonder about the strength of mixture. Bondo had very little strength. I've found that microspheres make a much easier filler to surface than Bondo. I've have done the opposite of your suggestion and used microspheres to thicken polyester resin for home brew Bondo. It works and sands easier and has greater strength. Only time will tell if the patches pop off my pickup.
Geo. C.