Updated: May 31, 2021
THE SOLID TIMBER CHALLENGE
Continuing my education about timber and its use in furniture making. I started sticking out local timbers when they became available usually through farm forestry operations, when they had an oak or elm log that did not fit in with their usual production they would ask if we wanted it. I invariably said yes. In that area in Pembrokeshire there was a lot of established timber craft businesses, not only furniture makers but wood turners and a boat builder. Even though we did not live near the ocean the boat builder was only 2 miles up the road and I spent a few winter nights picking his brains and drinking his home brew. His cottage was dwarfed by the stacks of oak stuck out air drying around his place.
Timber will always take in and let out moisture or water and instead of trying to eliminate all movement we must learn how to restrict it and allow it to move, swell and shrink when we make it into furniture. When our forebears made timber buildings in green timber they relied on the timber shrinking to tighten the joints in the framework and roof structure. When we make furniture for homes today the customer has the expectation that the timber will stay in the same condition as when they bought it. That the tops won’t warp and doors and drawers don’t stick. Manufacturing has got over this with board material, overlay doors and metal drawer runners. But where is the challenge in that?
We have to get to know the timbers we like to work with very well and what better place to do this than on a cabinet or furniture makers bench. Most pieces that we make take two to four weeks to complete and in that time you glue up tops, fit panels to frames, make drawers and doors. If the timber is not near equal to the moisture in the air you will soon know about it. All timbers have different characteristics and these need to be considered along with the intended use and moisture content.
Back to drying – trees are very good at moving water around. What we need to do to stop it shrinking when made into furniture is remove most of the moisture. There is a cell structure in wood and there is water in the walls and in the cell cavities. As the wood dries water is lost first from the cavities and the water in the cell walls remains and when this water moves most of the shrinkage occurs. You need to slow down the initial drying so that the water in the cell moves first, if the water in the wall moves first the cell water can be trapped and lead to cell collapse. When you stick out timber do it outside and cover the top of the stack and let the air flow through, if you are in a hot windy climate or dry cold conditions (freezing) cover the stack walls with plastic to reduce airflow temporally. Air drying is a lot slower than kiln drying and will take years longer to stabilize the timber but if you can successfully do it the resulting timber is much more satisfactory to work with, especially as said before minute changes can be noticed by the crafts person on the bench.
More coming my experience working with different timbers.