How Dry is Dry

[Dave Fritz]

Kathy's post on boxes and the comments on the dryness of wood raises a question. Rather than high jack the thread I'll start another.

At a recent demo Cindy Drozda showed her drying kiln. It was an old freezer with a hole in the bottom and a small fan with several light bulbs to provide heat. The heat would go up through the unit and out the top. I'm not sure how she knew it was dry enough but I suppose she either weighed it or used a meter to determine when it was dry.

What I wonder about is what is the desired moisture level and how will it remain stable when you move it from place to place or during the different seasons of the year?

Thanks,

Dave F.

[Glen Blanchard]

Dave - Others more well versed than I will chime in here but I am sure the consensus will be to that the piece should be dried until it no longer loses weight. A meter may be of some value (I occasionally use mine for this sort of thing) but weight stabilization is a better indicator.

[Michael Stafford]

I live in the coastal plain of North Carolina with lots of high humidity. Dry is 10-12% around here. I can dry the wood to less than that but shortly after taking it out of the microwave or drying box it will equilibrate to whatever moisture level is in the air. That is one reason I let things sit rough turned for months and months so that the wood and humidity can get sorted out.

The one thing I know is that as soon as you expose freshly cut wood to the environment of your shop it will react to whatever humidity level you have. I have sent boxes all over the world. In some climates the fit tightens up and in others it loosens. If most of your boxes are going to stay in the area where you are you can turn to a predictable fit. Otherwise you do the best job you can of having a reasonable fit that you hope will neither get too tight or too loose.

[Ralph Lindberg]

weight is how I check, I've had wood lose 50% of it's original weight before it's done

[Reed Gray]

Moisture content is always variable. The fancy word I believe, is 'hydrotropic' which means it is like a sponge. On boxes, I always rough turn them no matter how dry they are so they can 'adjust'. Just removing bulk will allow the wood to move. Like Michael said, Some places the lids will be tight, some places they will be loose. I never make threaded boxes, well at least not now, over about 1 1/2 inch diameter. Wood movement won't allow it. Larger canisters can be done, but you do not want a 'pop' type fit for the lids.

robo hippy