155: Steam Bending Bamboo Plywood

This month’s post is an attempted to add a new dimension to our laser cutting – literally. Sorry, I’ve been cooped up a little long, which isn’t making my jokes any better. But somewhere, years ago, I heard that you can use steam to bend wood. So this month, we gave it a try.

Here are some of my disclaimers: Most of the time, steam bending is recommended for solid wood, not plywoods, but I don’t have easy access to solid wood in the thicknesses we generally use for laser cutting (1/8 and 1/6 inch thick). Also, different kinds of wood react differently to stresses. Since I use bamboo ply in the majority of my jewelry, and my goal was to try and make a pair of loops I could use in earrings, I used bamboo ply in my tests.

I made a relatively simple shape, nothing too intricate, but would look cute in a loop. Length also helps with leverage for bending, so I made them long – 2.5 inches. I cut them so the grain is running the long way, in retrospect, I might have gotten more bed if I had cut them with the grain running the short way.

1/8 inch thick bamboo, 1/16 inch thick bamboo, and 1/8 inch thick balsa wood.

For testing purposes, I cut the shapes out of three different types: 1/8 inch bamboo ply, 1/6 inch bamboo ply, and just for funsies, some 1/8 inch balsa that was on hand.

Hot wood, coming up!

For ease, I steamed these pieces in my rice cooker. I have no idea if that is food safe (probably not), so I will not recommend you trying that at your home. I did my first test with a couple pieces, 1/16th pair and a balsa pair, and steamed them for 15 minutes. This did nothing to help their flexibility, so I put them in for another 40 minutes.

Balsa does not bend well!

The balsa was a joke – it broke so easily, and even steamed, felt like Styrofoam. The 1/16th bamboo ply, I fared a little better. I was able to gently get some shape by pressing them around the curve of a paint brush handle I had. I would press until I heard the grains creak or “snap” just a little bit. It was easier bending in the middle, with the ends as leverage; but there was no way that the ends would meet. There really wasn’t enough give in it, and they cooled rather quickly.

Slowly shaping the bamboo around the curve.

To see if I could get a little more flexibility, I decided to try and soften the fibers by soaking the pieces. I soaked a pair of 1/8″ and 1/16″ bamboo ply pieces, and a pair in balsa overnight, then steamed them for 45 minutes.

Soaking wood – the second bowl on top was to keep the light wood submerged. And yes, it colored the water.
A little curve! This was the soaked wood – you can see how “splintery” it is on the edges.

The soaked then steamed set actually produced worse results than the initial hour long steam. The bend ability was about the same, but the swollen fibers left the end result less smooth. When bending, the layers on the 1/16th bamboo split surprisingly easy, and there was a little more “ripple” on the inner layer. The 1/8 in barely bent at all, and the balsa wasn’t even worth mentioning.

Side by side of the 1/16th inch bamboo – soaked and steamed is on the left, just steamed is on the right.
Split layers
The 1/8″ bamboo is in the front, 1/16th in back

Overall, the process is a little fickle, and the bend wasn’t as dramatic as I had hoped. The process will work beautifully on larger pieces, but the process isn’t refined enough for jewelry, or at least, not the jewelry I had in mind. I did manage to do something with the pair from the first test, though!

One of a kind pair of earrings! 🙂


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