This is an excerpt from “Welsh Stick Chairs” by John Brown.
I disagree with people who say wood should be partly seasoned for steaming. The best would be ‘cut down yesterday, steam today’. Anyway, as soon as this ash is cut up it starts to dry. The moisture is sap. I drive it home and put it in a butt of water. Then I get my steamer rigged.
Two steamings a year supplies all the bends I need. My steamer consists of a 6′ length of heavy cast-iron pipe, 6″ internal diameter. At one end is a good fitting elm plug with a 1 ⁄2″ hole through it, in which is a copper tube. There is a wooden frame to support this end of the pipe and a pair of ‘scissors’-type gallows to hold the other end. The copper pipe leads into a 2-gallon stainless steel tank. (The tank came from the inside of a liquid vending machine and it is a pressure vessel.) For heat I use a trusty primus stove. The open end of the pipe also has a plug with a handle on it. I also have a small 1 ⁄4″ hole bored through this end with a removable wooden plug. I will explain why later. The whole pipe is lagged, sewn up in old rags and insulating material.
I start early on a steaming morning. Up at 6 a.m., fill the tank with water, light the primus. Everything must be ready and in its place, like an operating theatre. Forty ash sticks, pieces of string to tie round them so that I can pull them out, thick leather gloves, jigs for bending around, cramps, everyone I can lay my hands on, in fact no hold-ups. It’s like the morning of the big fight!
I can get from five to seven pieces in the steamer, it depends how curved they are. Each piece has string which hangs down under the removable bung. Gradually, the whole contraption heats up. By lowering the outer end of the pipe I can drain off excess water, for until the pipe hots up, the first steam condenses. At this stage I leave the small bung, in the 1 ⁄4″ hole that I mentioned, out. Soon, say by about 7.30 a.m., a small jet of steam comes out of this small hole and I know we have ‘steam up’. The lagging of the pipe is so important. What is needed for bending is heat, wet, and pressure. Now I have worked out that if I remove the little plug from the 1 ⁄4″ hole and the steam shoots out 6″ or so – I have pressure!
How long should I leave these pieces in? Difficult to say. About two hours is the norm, but I have left them too long when they get soggy and lose all the natural springy wood-like qualities. Really they want the minimum time that will allow them to bend. There are as many different theories as there are stars in the sky about bending wood with steam. What works for you! Meanwhile, I must prepare my jigs, and have a set of replacement ash blanks ready. I don’t want visitors today!
My jigs are all sorts. The first one is a very fine piece of work. A 2″ piece of elm, looking not unlike a chair seat in outline, nailed to a larger piece of 2″ elm. Around the perimeter of the jig, and about 11 ⁄2″ out from it, are 3⁄4″ holes at 3″ intervals. The idea is to bend the arm around, putting .” dowels into the holes, and then wedging the arm tight to the jig. It takes longer to write than it does to do! I have about four different shapes, and these determine the type of chairs I make. As the year goes on I judge what I will need. Some jigs are old seats that were too hard to chop. I bore slots at intervals about 2″ in from the edge. In making jigs I have to overstate the curve a little, for like all things natural, wood tends to want to go back to where it was.
9.30 a.m. approaches. Jigs are all ready, the first one cramped solidly to a bench. After all these years, the heart still beats faster. On with gloves. If ever the proverb ‘make haste slowly’ applied it is now. Out with the bung, a rush of steam. Pull the string you want, holding hot ash in one hand, replace the bung. Dispose of string and look for centre mark on arm. Now, place it on jig, bang in dowel, and wedge, ease round, no jerks, dowel and wedge, round, dowel and wedge, then the other side, round, dowel and wedge, round, dowel and wedge … it’s there, o.k….no split-outs. The tone is set for the day. And so it goes.
I have steamed six and had one good arm, I have steamed six and had six good arms. I could get masterful results by using a strap contraption. This is a method whereby a thin metal strap is clamped to the hot arm, and it is then bent round the jig. This requires more accuracy than I use. The pieces must be an exact length to fit in the end blocks of the strap. My main objection to this method is that if the arm is going to break or shred, better it happens now than when the chair is in use. Remember those lovely Thonet bentwood chairs? The wood for them was bent in huge numbers. Heated in an autoclave, and bent, dozens at a time in hydraulic presses. I have rarely seen one without a sheer brake, or incipient brake. Steaming is an art; science and technology cannot do it. Sometimes, having successfully bent an arm, I get the next piece out, put it on the jig, start to pull and realise this piece is not ready, although steamed for an identical time, and I put it back in the steamer.
I leave the arms on the jig for a couple of hours until the next lot in the steamer are ready. Then I release them and tie a cord across the open end to maintain the bend. Until they are cool and dry they will not maintain their shape. Steaming vastly accelerates the drying process. The sap is all out, and only water remains. The residual heat rapidly dries them. In one month they are totally dry.