Diatomaceous earth

martin ferwerda

W/C Canoes
So, I thought I would just throw this out here to see if anyone has any comments. When I first started building canoes, and looking into silica based fillers, my first thought was that one could use diatomaceous earth instead of the silica you can get from pottery shops. Freshwater diatomaceous earth (deposits of the skeletal remains of single celled critters) is used as a paint additive for flattening, and as a paint filler/thickener, among other things. The particles have a variety of shapes that supposedly improves the durability of paint. It is primarily composed silica, but has a bulk density roughly half of that of silica flour, which might be a nice property for those of us building 18 foot 80+ pound canoes.
I used to use DE mixed w/ water to coat the filter fabric of a, freshly cleaned, Plate filter press. Used to mix two bags w/ 100 gal of water and circulate it through the filter press until the return water was clear meaning the contents had been 'captured' by the filter cloth. It was enough to hold sludge that resembled the soft contents of a baby's diaper and allow the press to de-water the sludge into huge semi solid 'waffles'...

It is inexpensive and light. I think it would make a good 'body' for a filler.

One word of caution; it is an inhalation hazzard so a quality air purifying respirator w/ apprpriate dust filters should be worn. There is a calcium based equivalent that's more efficient @ twice the cost and is not harmful to your lungs.

Swimingpool outlets also sell it but I'd bet they are the most expensive place to get it.
Micro balloons had been talked about on the forums before they crashed, but the threads are lost. Not sure if it was in the context of a silica replacement for the typical silica base canoe fillers or other context. I have never seen any discussions of wood flour being used in filler formula. I have used diatomaceous earth as a partial replacement for some of the silica in the filler for a couple of canoes, but have yet to try a whole canoe with it.