Microwave wet wood for turning

In past responses to threads on turning green wood I have suggest using the microwave to dry wood. Now I had a project that was needed to be done soon so I took my own advice.

I have done it several times over the years, usually with small items, but this time I had a time critical need to do it. A friend had a cherished cherry fruit tree go down in an ice storm this winter. She had planted the tree in honor of her daughter’s birth.  I’m guessing by the growth rings of the tree 30+years old. She asked if I could make something like a bowl from it. At my age you never know how much longer I will be able to continue wood working so I used the microwave to speed things up.

The blank slab I started with was about 10” X 12”X 3-1/2” and so full of water it almost dripped. I let it dry for a week in my (cool) shop then proceeded to cut the bowl blank on the band saw. Then with a router, a circle template, and a dovetail bit, I cut a mortise on top side the size of the large jaws on my lathe chuck. Mounted on the lathe I trued up the bottom and sides adding another mortise to the bottom.  I then remounted the blank from the bottom mortise and proceeded to cut donut out of the inside of bowl leaving the outside walls about 7/8” thick and in the center column about 3” in diameter and on the top of the column a 1/4”  tenon that would be used to remount the blank when I was ready to do the final lathe work.  I then used the Forstner bit to hollow out the center of the column. 

 From there I began the microwave drying process. Over a period of 5 days I microwaved the bowl in the brown paper bag for about 2 minutes on each of the top & bottom making the wood almost too hot to hold….not quite. I left it in a paper bag slightly open and let it cool. I did this twice in the AM letting it stabilize during the day (in the bag) and repeated this in the evening.  On the 3rd round I noticed small cracking or checking occurring on the end grain of the wood and immediately treated the small checks with medium thick CA glue. Letting it soak in a little before spraying with an accelerator. That stopped them from getting bigger. I did get one small crack on the inside and stopped it the same way. During the final turning I was able to remove these cracks.

On the 3rd day an obvious warping could be seen across the bottom and top of about 1/4” measured from center to outside edges longitudinally with the grain.. After the 5 days I let it stabilize for a two days and then proceeded to finish turning it. The mortise and tenon I had made for mounting on the chuck had become very slightly oval in shape from the warping so I first trued them up to keep the piece concentric.  I then turned the bottom and sanded it.  Then reversed the mount and turned the inside of the bowl. As I got into the thicker area on the inside bottom curve I noticed there was still some moisture but a couple of 2 minute microwave treatments fixed that. 
I then put two coats of processed walnut oil on and let it cure for two days. Finally I will apply 3 coats of salad bowl finish (Generals) and deliver it to my friend.

Over all this took somewhere around 3 to 4 hours of my time over the week long process instead of waiting  months or years for the blank to dry naturally.  I think the friend will be pleased. She wanted it to be a memory piece of the tree she planted for her daughter.