Steam Bending: A technique of bending or shaping wood by utilizing the heat and the moisture from the steam.
The process combines the technology on both industrial manufacturing and handicraft, so, it largely depends on the experience of workers to complete the product in a good quality
So, how does steam bending work? The lignan which binds a piece of wood together begins to soften when it is exposed to the high-temperature steam in the steam box. At this time, the wood can be bent into a new shape. When it returns to the normal indoor temperature and humidity environment and the wood is fixed into a given shape, the lignan is cooling down and restores its original hardness while the bent shape is preserved at the same time.
The advantage of steam bending is that it maintains the original fiber structure of the wood, which makes the bending wood contains a more continuous structural connection and is able to bear more stress.
I did the steam bending on Red Chair. There are a few steps to complete the process:
- Make the jig first.
- You need to cut the wood board before you put it in the steam box. Make sure you leave some extra materials on both sides. (Hardwood works better with the steam bending technique than softwood.)
- How long will the steaming process take could depend on the thickness of the wood board you selected.
- The wood will be flexible and soft, AND HOT! Be careful about the steaming and the temperature. Wear gloves if necessary.
- Place the steamed wood in the jig and clamp the jig tightly to force the wood into the shape you want. It needs lots of strength to tighten these clamps, so, ask for some help.
- Wait for one or two days till the wood is completed fixed. Unclamp the jig and check the wood surface. Make sure there’s no crack or tear-out on the surface.
Common techniques in manufactory.
1: circle hot bending: driven by single axle roller, it is used to manufacture wooden products with closed rings, such as seat frame and armrest.
2: open hot bending: repeating press the steam heated wood on the mold, and finally make the contour close to the mold surface to form a hot bending degree, which is suitable for the open curved shape, such as the backrest of the seat.
- Author: Vable. “The steam bending method of wood is a shaping process without leaving any cracks.” SOHU NEWS. 2018.7.13. https://www.sohu.com/a/241039518_99927619
- Author: Jing Wei. “Steam Bending and Shaping”. 360DOC.COM. http://www.360doc.com/showweb/0/0/990911120.aspx