Friday, May 1, 2009

Gumming the seams

Armed with the purified tree gum from last summer, I set out to make the pitch needed to seal the canoe's seams. Set up a little workstation by the garage using an alcohol stove for the heat source and an old pot to mix up the brew.

Workstation with chunks of purified resin

The recipe and method I used was the same as that for the pitch on the miniature canoe - basically about 5:1 ratio of Gum to Lard, although this time, I decided on adding in some ground charcoal. Apart from blackening the colour, the charcoal apparently makes the pitch a bit less advesive when working it with the fingers. Some blackened chunks had been collected last summer from the communal fire pit and using a simple concrete block and a rock, the chunks ground to a fine powder.

Collected charcoal; Ground up with a rock

Once the mixture was hot and bubbling, a test strip of bark was added and then quickly dunked into cold water. After a minute or two, the test strip was bent back onto itself and if it cracked, a little more fat was added to the mixture. Satisfied that the pitch was the right consistency, I applied some of the warmed pitch on the masked seams of the canoe and worked it in with wet fingers. Not sure if the charcoal thing worked because my fingers were still a gooey mess so didn't take many pics for fear of covering the camera with pitch residue.

Pitch ready; Applied to a lap seam

I've used up about a 1/3 of my gum supply and need to mix up another batch of pitch to seal the ends and some gores and should have some better pics of the whole boat in the coming days

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