Drying Wood by boiling it has several advantages over traditional drying methods.
This article deals primarily with drying turned wood bowls, but the process can be adapted to other projects.
Pros and Cons of Drying Wood by Boiling
Drying wood in boiling water may sound bizarre, but makes a lot of sense.
It’s an excellent way to dry rough-turned bowls, and can be used on all types of wood and any size bowl.
Boiling seems to dissolve many of the tars and resins contained in the sap, which block up the wood cells and prevent the water inside from getting out.
When you boil wood, water stains mask the beautiful colors, but this is temporary.
You will cut through this stained layer during the final turning and reveal again the timber’s rich color.
Drying wood by boiling has several advantages over the traditional air-drying technique:
- There is a significant time saving- three weeks instead of six.
- There is far less cracking, though the wood still warps.
- It kills micro-organisms in the wood–a real advantage if you are working with spalted wood.
- You can dry big bowls, which won’t fit into a microwave.
But the fumes from boiling can be strong and unpleasant in the kitchen, and the heat needed to bring a large pot to the boil might discolor a stove top.
So it’s best, for marital harmony, to boil wood in your workshop or backyard, on a fish cooker like the one shown. Use an old can with a lid, rather than an expensive pot.
Start by placing your green timber between centers and turning it round.
Prepare the tailstock timber slightly concave, to leave the indentation made by the live center.
This indent will come in handy later, when you have to re-true the base for final turning.
Mount the timber on a faceplate or in a four-jaw chuck, and rough turn the bowl, leaving it fairly thick at this stage.
Leaving about 1 inch thickness for every 12 inch diameter will give you enough thickness to remount the bowl ton the lathe and turn it true, .after it has warped during drying.
Some soft woods warp so much that you will need to allow even more thickness.
Now boil the wood in water for 30 minutes, although it won’t hurt to boil it longer.
I bought a pressure cooker for this. Weigh down the bowl with something heavy to keep it submerged.
I use small scraps of steel.
Remove it from the water with tongs, forceps or pliers, taking great care, as this is boiling water!
Dip the bowl in cool water to keep it from burning you during handling, and place it in a dry, well-ventilated place.
It’s fun to see the steam given off at this stage.
The bowl may seem dry after a few minutes, but it isn’t.
Air-dry it in your workshop for three weeks, then start weighing it.
When it weighs the same for three days in a row, it’s dry.
After drying you need to remount and re-turn the bowl.
To do this you need to re-true the base, which will have warped during the drying process and will no longer be held true by your faceplate or four-jaw chuck.
Re-true the base between centers.
Mounting the base to the live center is easy if you still have the indentation made by the live center, to go by.
But mounting the inside of the bowl needs a little more work.
To do this, turn a curve that will fit into the bottom of your bowl, and put some soft foam on this curve to serve as a custom-fitting pad.
Place the bottom of the bowl against this and bring the live center up into the indentation.
The tailstock area of the bowl will now be centered, but the headstock may not be.
So bring your banjo up close to the bowl for use as a reference point, and turn the headstock by hand.
The bowl should stay the same distance from the banjo as it rotates. Adjust the bowl’s position to the headstock until it runs true.
Deduce you lathe speed and true the base to fit your faceplate or four-jaw chuck.
Remount the bowl and turn to completion.
The timber will be very dry and won’t cut as easily as green wood, so use sharper tools and a careful technique when cutting.
Use the finish of your choice.
If you are going to texture the bowl, do it while the bowl is still on the lathe.
Reverse the bowl and clean up the bottom.
Yes, boiling wood is a useful technique, and I urge you to try it.
If you have a big enough pot you can “cook” several bowls at the same time.