It is really just wood dust/saw dust that is (or has been ground to) a "flour" like consistency. I am not sure if it would go by any other name... but perhaps you might want to check with a local lumber yard or sawmill.

Of course someone else on here might have a better suggestion (or perhaps offer a reasonable substitute)

I have a similiar problem in trying to find a local supply shop that carriers graphite powder; so far I have only had one shop actually know what I was talking about - but did not carry it in stock. I was trying to avoid having to pay $10+ in shipping for a <$10 can online.

Wood Flour is fine sawdust.  If you own a beltsander with a dust bag, you can make your own.  The dust from saws is to coarse, it really does feel like flour.  It's main purpose is to add color to your fillets, wich will be darker than your wood with pure woodflour.  So if you are going to paint, then you can just use glass balls, cab-o-sil, etc....  To adjust the color on my fillets I use glass balls and woodflour together.

I dont know where you are looking, but I have seen Graphite Powder at a couple of Boat stores (West Marine, Boat Supply,), our local glass supply house, and our locksmiths. 

Thanks for the tip, I'll try a few locksmiths - it was actually a west marine that knew what I was talking about, but did not stock it at any of their locations here in Michigan. For all the other boat supplies they were not familiar at all (They all seemed to carry the MAS lineup, which does not include Graphite)

A bit of a correction here - woodflour's main purpose when building S&G boats is to make epoxy (normally a viscous fluid) into a thixotropic fluid (one which gets less viscous the more you push on it). It also acts as a thickener. The result is that the epoxy can be formed into a glue or putty. The putty is less brittle than ones made with cab-o-sil or glass or phenolic microballoons, much easier to sand than cab-o-sil and glass balloon putties and it doesn't sag as much as phenolic microballoon putties.

Woodflour is also non-toxic, though a lung irritant and potential allergen. And as KK mentions, it can also be used as a coloring agent.

Woodflour glue is plenty strong enough to handle the structural loads for the kinds of boats sold here.

Laszlo

Buy WEST SYSTEM  " 405  Filleting Blend" 

Laszlo

I usually use the fumed silica thickeners for strength and thixotropic qualities, woodflour for general fillets, and microballons for light weight and sandability.  Always adding a bit of silica/cab-o-sil to woodflour if I need smooth fillets.  I thought the strength and brittleness of thickened epoxy, from worst to best, generally went from microballons to woodflour to silica.  Am I all wet, again?

where in Canada are you?  In Toronto is Noah's Marine Supply that stocks wood flour and graphite (just bought a tin on Tuesday).

 http://www.noahsmarine.com - they also ship.

BTW they have 4mm Okoume for half price, the container leaked and there is a water stain at one end, about 8"  Bought enough for my Wood Duck and C18!

System Three sells it in quart containers. I get it at Woodcraft http://www.woodcraft.com/product.aspx?ProductID=124529&FamilyID=338

Making your own with 100 grit sanding looks the same but you can really match your wood color that way. It doesn't say what wood this is made from.

I remember reading somewhere that, in a pinch, you can use wheat flour as a thickener.  I did this on a 2 different CLC boats and they have both been in use for 8 to 10 years.  I don't think that I'd get carried away with using wheat flour, but it did work for me.

ootdb,

Once again, it depends on what you mean by strength. Not only that, but the qualities differ depending on the filler/resin ratio.

Microballoons are quite strong in compression, abrade relatively easily compared to the others and are weaker in shear, torsion and bending than the others because of the hollow spheres. Good fairing compound on top of a solid structure, easy to sand, should not be used as a structural component on boats that will see a lot of stress, especially not as a glue.

Woodflour is resistant to compression, shear, torsion and bending. Also somewhat flexible depending on the flour/resin ratio. Hard enough that sanding is a nuisance, so not a good fairing compound, but excellent glue. Its thermal coefficient of expansion matches plywood more closely than the others, so there will be less print through of plugged holes over the years. Will make lumpy fillets if mixed thick, but can be smoothed with a thin coat of epoxy before it sets.

Silica, literally powdered sand. Add epoxy, let it cure and you have a synthetic rock. Very hard, resistant to compression, shear, torsion and bending, though can be more brittle than the others depending on the mix (but not an issue on low stress boats like kayaks), makes smooth fillets.  Can be mixed with other filler types to improve smoothness or reduce sagging. Hell to sand.

So basically, for the boats sold here, don't use phenolic microballoons for glue, anything else is a matter of personal preference. For powerboats and high performance planing sailboats, follow the designers' recommendations.

Laszlo

Laszlo

Thank you!