Bending Wood for Chair Parts

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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!

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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.

Meghan Bates

This entry was posted in Welsh Stick Chairs by John Brown. Bookmark the permalink.

6 Responses to Bending Wood for Chair Parts

  1. Bob Glenn says:

    Interesting, in that I just bent an oak crest rail for a windsor side chair yesterday. I usually use a steam box, however, due the small size, 1x4x26, I used the water trough that I use process Shaker box strips. The oak was previously kiln dried, so I soaked it in water for a week before bending. I boiled the oak for about a half an hour before bending and all went well. It is an art.

  2. jenohdit says:

    Could you put some sour mash in the pot and make whisky at the same time?

  3. artisandcw says:

    I do not make chairs a la Welsh chairs (I make Gragg chairs) and have no opinion about the efficacy of Brown’s methods. I’ve found that bending fresh harvested green wood has resulted in too much spring-back for my projects without lengthy restrained seasoning ex poste, which sorta defeats the purpose. Letting wood season for a long time prior to bending seems to help with my work. It is only one data point, but yields an R Value of 1.00 (an old chemistry joke).

  4. Michael says:

    I’ve done a little bit of wood steaming using a steam wallpaper stripper. It was connected up using airline quick connect fittings, amusingly the connector on the stripper was the right BSP fitting! My 1st tube was with PVC plumbing pipe, it couldn’t take the heat and was replaced with aluminium vent pipe. It also made a difference to wrap it in an old blanket for insulation.

  5. Richard Sutton says:

    Having used both dry and green wood my vote is for fresh green ,split out and steamed the same day. Welsh stick chairs changed the way I spend my free time. My original copy is still on the shelf above the bench.

  6. Paul Huckett says:

    In the 1970s we holidayed on a beach in southern New South Wales, Australia , a fabulous ocean surf beach . For three or four years an American yacht builder laboured to build a replica 17th Century sailing vessel on the beach , an amazing craft . He had built a huge steamer out of 40 gallon drums welded together to be able to shape all his planking . He fell and milled timber from the local hardwood forest , mostly eucalypts I suppose. We watched each year in awe at what one man could do. The huge steamer fascinated me . One year he was gone and the old steamer is probably still rusting in the bush . How he launched it, I have no idea . High tide and a tug maybe ! I saw him once again, years later, carrying tourists on pleasure cruises in tropical northern Australia . He was dressed as a pirate !! Your article reminded me of him and his steamer

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