The larch which Alan (Collett) collected from the sawmill in Yorkshire, using John (Seymour’s) trailer looked very clean, knot-free and straight grained – ideal for bending. it was clearly green and moist – further ideal qualities for bending into our stems and aprons (the long curved extensions of the keel at both pointy ends of the boat.
Being moist, our polymer based epoxy glue would not bond to the timber, so I used a polyurethane glue which requires a degree of moisture to cure. The blurb on the web stated it could tolerate up to 25% moisture content. At the time we had no moisture meter with which to test our larch.
We pressed on confidently, assuming all would be well, glueing strips of larch and bending them round the jig. On Sunday Chris, Barrie and I were cutting the forward apron to fit when it sprung apart. Careful prodding of the other laminations showed them all to be failing.
Gently prising the laminations apart we salvaged the larch intact and Chris set to cleaning off the residual glue.
Vicky managed to borrow a moisture meter from Neil Thompson at Glandford and we were able to establish that our larch ranged from 18% – 23% moisture content.
Hidden deep in the small print on the can of glue it stated that the figures given for drying times etc. were based on a moisture content range of 8% to 18% in an ambient temperature of 20 degrees C.
The net outcome is that I am having to let the larch dry out, checking the meter regularly. This could take a few days, meaning there is again little else we can be getting on with this week – very frustrating.
My concern is to get the balance between reducing moisture levels for the glue but not drying the larch too much so it then cracks when we try bending again!
I will keep you posted. IAN