I haven't used Durhams-it's not available at HD in Canada

To Bad, maybe I'll have to take orders and fill my boat with it the next time I visit family in Toronto.

From the Canadian Woodworker's page:

"Re: Durham's Rock Hard Water Putty

Water Putty is one of the best, and cheapest, forms of wood filler. It doesn't shrink, and it takes stain very well, so it can be blended with pigments or paints to match the wood. After 20 or so minutes of curing it can be carved with a knife to build up missing moulding, etc. After 40 or so minutes it is Rock Hard. Since it's shipped as a powder you can mix it to whatever consistency you want, so you can make a heavy paste for building up missing chunks, or a thin paste for filling pores, etc. Lovely stuff. So I hear, anyway. I haven't yet had a chance to actually *use* it, yet. Oh, and as a powder it has the shelf-life of plutonium so it never goes bad. You mix it as you need it. It's the wood-filler equivalent to shellac flakes, if you catch my meaning. Of course, you mix the water putty powder with water, not alcohol.
Five dollars buys you a 1lb can of powder which mixes up into a fair pile of putty."