Drying Turned Wood
by Gerald Lawrence
I will cover the method I use as well as some other methods which have been up and down in popularity in the woodturning world to dry a blank in a method of turning called Twice Turned. First what is Twice Turned (TT) . TT is when you rough turn a bowl (usually only green wood) down to a wall thickness equaling one-tenth of the diameter of the bowl, the turn again when it reaches moisture equalization (MEQ) to final finish.
1. Bag & Chips OK that does sound like fast food but that is what I will call this method which is the one I use mostly. After rough turn I weight the bowl and place in paper (note plastic will not let moisture escape and cause mold) bag with shavings from the turning. This bag may get wet and for the first 1-2 weeks open it up daily to let out some moisture and possibly even change bags. I at one time weighed each time I went to the shop but now have that down to twice a week.
After about two weeks or less when drying slows the chips can be dumped and keep in bag only. Continue weights and when the weight loss drops to average about 4 to 7 Gm a day take out of the bag and place on shelf. Store top down will slow the water loss some. When you reach MEQ or 1 Gm or less change you can stop weights and store till ready to do the second turn.
2. Alcohol Bath is based on the principle that alcohol attracts water . This
means that the alcohol absorbs water from the blank . This alcohol will continue to absorb water to a certain point at which it becomes saturated and must be dumped. The alcohol used is 95% Denatured Alcohol (DNA).
Use plastic buckets or barrel to place bowls in with it completely submerged in DNA. May need a weight to accomplish this. Leave in DNA for from 2 to 24 hours (studies disagree on the time so experiment) . Remove bowl and allow excess to dry . Wrap the outside only of bowl and rim with paper. Store on stickers to allow air flow. May be returned in as little as two weeks.
3. Seal and Store is a method used by many pro turners since time is of essence. Rough turn the bowl and seal endgrain inside and out with Anchor Seal and store the bowl. You can either wait a long period (six months or more) or use moisture meter to check for MEQ.
4. Microwave you would place bowl in microwave at high for about 20-30 seconds and weight after each cycle. Wood must be allowed to cool after each cycle for a period of at least 30 minutes.. This may take 6 to 8 cycles to get to MEQ but do not rush it or you can have burned bowl to contend with. The sie of bowl and type of wood also affect the use of this method.
5. Desiccant Drying is a fairly new method . This one uses desiccant crystals which can be bought in bulk on Amazon and other places . Right now 5 pounds runs around $30. Just place the bowl in a zip lock bag with enough desiccant to cover it. This can completely dry a bowl in as little as 24 hours. Some of these beads will change color as they absorb more water. Check weight or use meter to determine dryness. And repeat if needed. A good thing about this method versus alcohol is that these crystals can be recharged by drying them in the oven.
6. Kiln Drying is a method you can use for fast results. There are many videos and instructions on the internet as to how to make these. Most use a old refrigerator or even a dishwasher, two holes at least will need to be cut in it, a top and bottom to circulate air. Muffin fans can be used to circulate air and a light bulb to generate heat, Timers and thermostats can also be used to enhance the effect.
These are mostly a short story on drying bowls and there are exceptions to every method and this is only to give a close overview of what to expect in use but not a guarantee of results. Different types of woods dry at different rates and some will dry catastrophically with a push method. Overall don't be afraid to try passive methods and experiment.