My experiments with bending strips of oak continue. A friend-of-a-friend who is a guitar luthier was kind enough to give me some advice over the phone, based on his experience of bending veneers around the body of a guitar. But his advice did come with the caveat that the veneers he uses are generally around 2mm thick not 6mm, and he doesn’t often use oak.
He suggested soaking the wood overnight in the bath and then forming it by hand around a metal pipe heated by a hot air gun, placing a wet rag around the pipe if the wood dried out too much. I asked about using fabric softener to make the wood temporarily more pliable, something I’d read about in online forums. The luthier had heard of this method but never used it himself; he thought it was worth a try though.
First problem: finding a vessel long enough for soaking my test strips, some of which are nearly 80cm long. The bath wasn’t going to work because the plug leaks a tiny amount, and I didn’t want to waste water by filling the bath to the brim to ensure there was still enough left in the morning. I found a length of rainwater downpipe that was long enough, but I didn’t have anything that would seal one end. Likewise with a length of half-round guttering (except that I would need two end caps for that). Looking around the house, I came across a long, narrow drip tray in which my dear husband stands pots containing seedlings on the windowcill. Happily, it’s just over 80cm long. I managed to fit all the strips into it bar one extra long one. I let them float – perhaps I should have weighted them down, who knows.
I painted neat fabric softener onto the middle section of the final strip and then wrapped it in clingfilm.
The next morning, my options for forming the sodden strips were limited because I don’t have a hot air gun. Instead, I clamped a matching pair of strips around the dustbin lid, like last week, and left them in the sun all afternoon to dry. When I removed the clamps the wood sprang back a bit, but no more than last week’s steamed strips did. Curiously, one of the strips again took a tighter curve than the other – maybe that’s because the lid is quite battered and distorted.
I quickly PVA’d the outside of the more tightly curved strip and the inside of the second and clamped them back around the lid, one on top of the other, to laminate them. That took every G-clamp we own, it’s much harder to get two strips in contact with each other all along their length than to curve them individually around a former.
With no more G-clamps and no other suitable former, I’ve used our ancient sash cramps to bow the remaining three, shorter strips. This time, I actually remembered to curve one of them with the “good” surface of the oak on the inside, so I can laminate a pair back to back and have a “good” face on both sides.
Everything is drying at the moment – the glued pair around the dustbin lid and the three bowed strips held by the jaws of the cramps. We’ll see what the end result is like, but the soaking process was certainly a lot less of a palaver than getting out the wallpaper stripper and connecting it to a pipe. Not to mention having to dry the steamer, hose, pipe and funnels and put everything away again afterwards. The bending part of the job was less of a race against time too. I imagine that a well-soaked strip of wood will remain pliable for hours whereas steamed wood has to be clamped to its former without delay, because once it starts to cool the lignins stiffen again. The only drawback I can see in using water rather than steam to make the legs of my coat stand pliable is that it will be easier to steam just the middle section that I want to bend than soaking just that section.
I did try another bending method, the hot pipe technique, but it wasn’t entirely successful. It’s not really the weather to be firing up the home-made wood-burning stove, but we burn things like bank statements in it every now and again, even in the summer – who needs a shredder? The stack of paper waiting to be destroyed was enough to provide a few minutes of heat, and the cylindrical flue soon got too hot to touch, but I’m guessing no more than about 100°C. Wearing leather gardening gloves, I tried forming a rather ropey strip around it.
Naturally, I haven’t used pristine engineered boards for this series of experiments, rather offcuts and boards that were rejected by our floor-layer because they had prominent knots or cracks filled with epoxy filler. These rejected boards have been stored outside (but under cover) for the last 9 months, which hasn’t improved them. I’ve found a few woodworm holes in my test strips, and the one I had left for the hot pipe treatment had a long, filled crack in it. The oak seemed to curve quite readily around the flue, but the filler soon began to separate from the wood – epoxy filler is clearly a lot less flexible than hot, wet oak. When the fire lost its heat I took the newly curved strip away from the flue and tried to hold it in an arc with a bungee while it cooled. The force was too great and it split in two along the crack. It has definitely taken on a curved shape though, and I can see that this method – with practice – could be used to produce whatever degree of curvature is required without having to go to the trouble of making a former. It was gratifying to find that it worked, even on 6mm thick veneer.
As for the clingfilm-wrapped, fabric-softened strip, it will have to wait until I have some clamps free. The wisdom of the internet suggests the pliability occurs when the wood has dried, but only lasts for a day or so.