Wednesday, August 26, 2009

Runny Spruce Pitch

The last week has been a scorcher by this season's summer standards. Temperatures in the 30 degree Celsius range with the humidex making it feel much hotter. While many sun worshippers have welcomed the change, I've always despised steaming hot weather. Seems like my bark canoe doesn't like it either.

Back in the early spring (May) when I first tested out the boat, I made the spruce pitch according to the temperatures of the time. The ideal ratio of tree gum to fat in the pitch is dependent ambient temperature of the season. Too little fat and the pitch will crack and chip off in colder weather, too much fat and the gum will become runny during hotter days. Well, I must've put in a tad too much fat, because after resting the canoe on horses in the protected confines of the garage, I awoke to the horror of messy, melted, runny pitch leaking down the side of the canoe. The stern in particular took the brunt of the ugliness, as I had loaded up on this weakpoint where most of the leaks seemed to have originated.

Runny pitch down the sides; Lots of runny gum on the stern

I guess the short term solution is to sit the canoe right side up on some slings and hope the gum runs back down to the seams. Either way, my ugly duckling of a canoe now looks like she's got runny mascara.


Ted B. said...

What a runny mess! I'm so sorry you are now saddled with the problem of fixing it. Please let us know when you find the solution, if there is one. Global warming could mean that a lot of other canoes will be having the same problem.

Ted B.

Bob Holtzman said...

No suggestions for fixing this. To prevent it in the first place, however, I believe that ash and/or powdered charcoal was added to the fat/gum mix. It prevents running in hot weather, although it does make the mix brittle in cold weather.

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