Tuesday, 20 August 2013

Ha'porth of Tar?

Drat! As I started cleaning up the glued bow I noticed a couple of hairline gaps at the join. I wasn't very happy.
When I'd glued it up I'd seen the glue seemed to be soaking into the bamboo a bit and at one point I'd added a bit more as I was binding down the backing. In retrospect I should have undone it and added an extra bead of glue along the whole glue line and the re-strapped.
Why didn't I?
Well, the instructions for the glue say only glue one surface, but I always glue both, precisely because I don't want to risk a dry joint.
Normally as it's bound down I'd expect some slight squeeze out of glue along the edge. Indeed, that's what I'd got along most of it.
The slight gaps were barely visible and maybe only went under the 'boo a tiny distance, but how could I be sure? Perhaps I should have added a second layer of binding? Would that have done it?
I rubbed in some freshly mixed slightly thin Resintite massaging it into the join as a half hearted attemt to 'fix' it, but I still wasn't convinced.
One of the gaps was under a node and the thought of a dry glue line under the node didn't fill me with confidence.
Did I really want to risk a couple of hundred quids worth of bow for a slat of boo that cost £6 ? It hadn't taken me that long to do the job in the first place. I've had a couple of breakages recently and did I want to risk another?
I was really glad that I bought plenty of 'boo and had thus saved on the shipping cost.
My wife finally convinced me when she said "you're not leaving it like that?" and she's seen enough bows made to be virtually an honorary bowyer herself!
Rather than prevaricate I picked up the plane and set to taking off the boo.

I wish I'd taken pics before I massaged in the glue but the pic does give an idea of the size of the gap, if you look at the glue line near the top of the pic is is barely visible. The second pic shows what does look like a dry area.
I shall make a virtue of necessity and glue a little more reflex in this time, I will also increase the taper a whisker and even it up more before the glue up this time. Or to put it another way I'll just take more care and do it right.

Resintite does have 'gap filling' properties and that fine gap would have been ok had it been solidly filled with glue. The ideal glue line is about as thick as a hair, or at most as thick the fingernail on your little finger.

Would it have failed? Who knows.
The moral of the story is always listen to that little voice of doubt that says "that's not right" especially when the glue stays workable for 2 hours and there's not really any rush.
I've got it back down to the wood already, but I'm not going to try and re-glue it tonight... oh deary me no!
But maybe I should add that £6 and the 1/2 penny worth of glue to the price of the bow? ;-)

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