While we were restoring a large Victorian building in San Francisco, we had to bend a lot of redwood trim around 4-ft. and 12-ft. diameter framed partitions and enclosures. Steam-bending seemed like the easiest way to do this, but because the trim pieces were so long, we had to devise an equally long steamer to accommodate them.
I went to a scrap-metal yard and bought a 14-ft. length of 6-in. threaded cast-iron pipe for $25 (8-in. pipe was also available). I also bought two end caps. I put a thin layer of plumber’s putty on the threads at one end of the pipe, and tightly screwed on one of the caps. Near the opposite end, I drilled a 1/4-in. safety-valve hole, and tapped in a cedar plug. Then we put the capped end into the building’s fireplace, built a fire around it with wood offcuts, and poured in about a gallon of water.
About 20 minutes later, the pipe was steaming, and I picked out four pieces of the redwood trim with the most vertical grain, shoved them inside and screwed the second cap on hand-tight. After another 20 minutes we uncapped the steamer, removed the wood (wearing gloves) and cut it quickly. The redwood easily bent to the required curves.
As we grew accustomed to the procedure, we precut the trim pieces because working time is short — about 3-1/2 minutes. Experience also taught us that vertical-grain pieces were much easier to bend than flat-grain ones. With flat grain, the growth rings tend to separate during bending.
The advantage of this steamer is that 20-ft. lengths of trim can be steamed, by joining two pieces of pipe with a union. Also, most job sites have scrap wood and a safe place to build a fire. The disadvantage is that cast iron stains redwood black. This isn’t a problem if you’re going to paint the trim.
Michael Spexarth, El Cerrito, CA