At the Cab-o-Sil web site, they talk about mixing fillers with the resin before adding the hardener. It will work; however, once the fillers are in, the resin will be more viscous (the purpose of the fillers) and you'll have to be more careful getting the hardener mixed in properly.

: Hi All : Finally getting a chance to play with a boat, but, not mine. My
: brother purchased a Glen-L, "8 Ball" about a year ago and got a
: little out of wack with the stitches and sorta gave up until fishing
: season this year. I told him to bring it down and I'd play Chiropractor
: and get it back in shape. So, I've done that and it's ready to fillet,
: pull wires and attach seats and such. My question may be a no-brainer,
: but, would like to get some feedback anyway.

: Question:.... The Glen-L epoxy resin instructions say that you have to mix
: the epoxy first and then add the fillers. I'm working in approx. 90*+
: weather here and even in the 80's till 10:00 P.M. That will significantly
: cut down on my working time if I'm thinking correctly. So, I've heard that
: others have mixed their resin with the fillers and then added the
: hardener. As most epoxies are near the same, would I be correct in
: assuming that I may do the same with this brand? Does the adding of
: fillers retard or eccelerate the work time? I'm using micro-balloons and
: silica, as that is what his kit provided. No clue on the speed of hardener
: as the can is marked "Part B". I haven't tried any glassing or
: resin work as of yet, but, I'm sure I'm talking about mere minutes of
: working time here. My brother has worked with resin and fillers before on
: a little hot-rod he built and said that the fillers take a little work to
: mix into the resin, as they are so light they want to float on top. Sounds
: like fun, but, If I spend too much time mixing, then I will have a very
: large white blob-on-a-stick. I want to get this thing done so I can get to
: Great Auk. :) Thanks for any and all comments.

: Rehd