"dadiOH wrote:

2. Bondo (cheap) which is polyester resin and talc. Sands easily
but
less so than #1. Source: auto parts store. Won't stick as well as
#3
but I used it years ago from time to time on a 40' ketch with no
problems. Certainly, none above the waterline.

IMHO, should be used on cars.

As indicated, has some problems.

3. Epoxy resin thickened with talc or Cabosil. Filled with talc
sands
easier (but less so than Bondo) but is heavier than filled with
Cabosil. Source: epoxy vendor. Note that it may be hard to fair
off
a surface where it has been applied as it will be harder than the
wood...best to appy an unfilled coat over all, then fill and sand.
IMO, YMMV.

Epoxy is the best choice when filled with micro-balloons to make
fairing putty.

Talc is heavy and adds no strength whatever, just sucks up epoxy.

Best left for the Bondo applications.

Cab-O-Sil is improve hang time, but is imposssible to sand and I found
unnecessary.

You add Cab-O-Sil to fairing putty until you learn better.

Again, YMMV.

Have fun.

Lew