Bending Dowels Permanently
Creating a lasting bend in a wood member requires steam heat. March 26, 2013
I market children's kites, one style being like Ben Franklin's diamond shape kite. I use a 1/8" birch dowel for the frame 24" long one is straight one is curved. Currently I wet down the one to be curved and place them in bundles of 100 into a jig that creates the proper curved shape. I get complaints that when the finished product is exposed to moisture or high humidity the curve straightens out. Not a good thing as the curve provides stability in flight.
I need an inexpensive sealant to stop moisture attacking the dowel. My thoughts were immersing the bundles of dowels into a vat of sealant and then putting them in the jig to shape. I normally leave the dowels to set 24 hours. What product would you recommend as a sealer? I was thinking about waterborne lacquer thinned down well to prevent sticking to each other. Part cost for my finished product is important.
From contributor D:
Why would you think thinned down waterbased lacquer would prevent these pieces from sticking together? Water based products dry by evaporation. Once the water evaporates you are left with a layer of the product. Adding more water will increase the drying time and thin the product, but will most likely not prevent sticking together. I would think you may need to bend these pieces as you have been doing and sealing them with a solvent based product once shaped to prevent moisture from straightening them back out. Also, solvent based products dry much quicker.
From the original questioner:
My thought about cutting the lacquer was for better penetration and less surface deposit. I experimented with a wood hardener product and it was acceptable. However it is expensive for my needs. I like your solvent base suggestion.
From contributor T:
Surface coatings cannot prevent moisture penetrating or exiting wood, it can only slow it down. You will have to steam bend them for a permanent curvature.
From contributor M:
Paraffin wax is one of the best sealers for wood against moisture. Maybe that would work for you?
From contributor O:
I agree. Chasing a finish and related process is not going to achieve what you need. Steaming those dowels will be easy to do in a large batch, but will require a little research and problem solving on your part. With the parts steam bent, moisture changes after the dowel leaves your hands will not affect the curve. Result: blue sky and signing birds.
From the original questioner:
Contributor O - steam seems simple. I didn't know the set would remain after drying. Originally I was only immersing in warm water. The steam process will save me production bucks if it works. I have a small steam jenny. I'll make a test chamber and experiment.
From contributor I:
If I remember this correctly, the steam heat works at a cellular level. It softens the lignin that holds the cells together. When it cools, the cells are realigned. Luthiers use a torch in a pipe. They move the wood over the outside of the pipe to soften the lignin. There’s no drying time or rough wood from the moisture. Maybe you can use this technique and throw them into a form to cool off for instant bends.