Replies

1. 
   Rich14 | Sep 26, 2008 04:14pm | #1

   sk2tobin,

   It all depends on what you want to use it for. If you had asked how you could tell if a board, purchased from a "lumber supplier" were ready to use for incorporating into a piece of furniture, the answer would go something like this:

   The board needs to have been reduced from its initial live, wet condition to an "Equilibrium Moisture Content" of somewhere between 7%-11%. Wood allowed to air dry to an ambient atmospheric relative humidity of about 40%-60%, or wood properly kiln dried and then exposed to the same ambient atmospheric conditions will achieve an EMC somewhere in the acceptable range of 7%-11% for wood working.

   That board from the lumber supplier can be expected to be relatively flat (therefore useful) when it has been dried to the desired range. But it will not really be ready for use until it has come to its final equilibrium in your shop (if your shop's typical relative humidity is different from that of the storage conditions at the lumber supplier's storage). In all probability there WILL be a significant difference in those two ambient conditions and you will need to let the wood acclimatize to your place.

   Which finally brings us to an answer to your question. You could measure the EMC of the wood with a moisture meter (usually in the range of $150-$250) until readings became stable over a period of weeks at some number in the 7%-11% range. It might take a few weeks, a few months or a few years until that stability were achieved, depending on the thickness of the wood.

   You could also determine equilibrium by cutting off a small piece of the wood, keeping the piece stored with the main board(s) and periodically weighing it with an inexpensive but very accurate electronic scale ($30-$50) until the small piece stopped either gaining or losing weight (gaining or losing moisture to the atmosphere).

   The problem with your wood sample is that it has come from the branch of a tree, not from the straight trunk (bole) from which lumber for furniture use is obtained. It has all kinds of internal stresses that will make it useless as "lumber." you will not be able to flatten any part of it and be able to depend on it remaining flat. It's internal stresses will give you problems far beyond that which would happen due to inadequate drying before use. Such wood may be good for carving, creation of artifacts, "objects d'art, " etc. It may have some very interesting, "wild" grain and figure.

   I would cut off a small piece, and monitor its weight with a sensitive scale while both the piece and the entire wood sample were kept in your work shop, assuming your work shop has a somewhat stable ambient temperature and humidity. Once there is no appreciable change in weight of the sample over a several week period, you can probably use the wood for whatever you intend, as long as you are prepared to deal with releasing of internal stresses as you cut into it.

   Rich

2. 
   HowardAcheson | Sep 26, 2008 06:36pm | #2

   First, wood from branches typically is not used for furniture. Branches have inherent stresses and tend to warp in unpredictable ways.

   Second, there is a "rule of thumb" for drying of one year for each one inch of thickness. However, this is very rough and variable. Species, relative humidity of storage and air movement are just some the variables that affect the time. The best way to know is to use a moisture meter.

   Howie.........
1. 
   sk2tobin | Sep 28, 2008 03:51am | #3

   Well this piece is from a branch but the grain is as straight as other pieces I have bought from the lumber yard.  I am not sure if that makes a difference in the internal tension in the wood.  What do you think?

   Thanks,

   SK2

1. 
   Rich14 | Sep 28, 2008 05:21am | #4

   SK2,The appearance of the grain is no indication of internal stress. You won't know if there is a problem until you cut into the wood. If there is unbalanced stress, cutting into it will relieve the stress in one place vs another and warping will occur. The warping will be in several planes at once and will not be able to be controlled.Rich