Hi Carlos, 

in the CLC epoxy kits they include the two additives (wood flour and cell-o-fill) you identified that can be mixed into epoxy to thicken it so that it can be used for glueing parts or filleting joints. 

these additives come into play mostly in stitch and glue boats (vs strip build) and you can look at some links on the CLC site to get a sense of how they are used in stitch and glue boats.

https://www.clcboats.com/shoptips/building-stitch-and-glue-kayak/   see the entire series and you will see where woodflour and cell-o-fill get used.

in summary, wood flour is typically associated with making fillets.  cell-o-fill is for making a thick epoxy glue.

i build a lot of strip boats and i don't use a lot of these additives....the only place i recall doing that is if i am making a fillet where i join the coaming to the hull or attaching cheek plates or wooden bulkheads......or thickening the epoxy with cell-o-fill when i join a deck to the hull.

but for strip builds, carpenter glue is the main glue you use for all the stripping....and the wood flour and cell-o-fill  materials don't come into play for that part of the work.

after you look at the links i think you will see where it might be used....but again for strip builds, you will use little if any of this material depending on the particular design you are building.

i hope that helps.

h

Direct link to Episode 5 - The Gluing Part of Stitch & Glue.

Laszlo

As always, good comments by Laszlo and hspira above.  A couple of additions:

1.  I tend to do hatches and plywood cockpit coamings on my strip boats.  For those locations, I use epoxy thickened with cell-o-fill.  I use the same for external stem glue-ups.  For areas that will be highly visible like the coaming, I add just a touch of wood flour which makes the glue a closer color match to the wood.

2.  For the hull/deck exterior and inside of the hull near the cockpit, I use epoxy thickened with both cell-o-fill and wood flour to fill any blown seams.  If you play with the misture of the two ingredients, you can get a color that closely matches the wood.

3.  Another good additive is micro-ballons.  Mixed with epoxy they form a light and easily sandable fairing compound.  This is what I use to fill bad seems in locations that will not be seen like the underside of the deck and hull interior forward and aft of the cockpit.  This also makes a better end pour because it is lighter.

This picture is microballons/epoxy used to fair the underside of the deck.  The color is not good for the outside unless you are goint to paint.

Glue-up of laminated external stem with cab-o-cill and epoxy mixture.