Care of Your Interior Use Lumber & Millwork
We take great care in buying, storing and working with properly dried high quality lumber. Once lumber and millwork leaves our shop there are a few things to know that will ensure the wood remains flat and stable.
Wood is hydroscopic; it absorbs and releases moisture relative to the humidity in the air. In other words, wood expands and contracts with changes in humidity. Although application of a finish somewhat slows down moisture transfer, there is no finish that will stop the natural process of moisture absorption and related movement. Thus, when dealing with solid wood three things are important to understand....proper storage, proper finishing and proper installation procedures.
Storage
Lumber and millwork should be stored horizontally in an area that has the same humidity levels as the installation site. If you have to briefly store lumber in a garage, basement, unheated barn, etc... extra care should be taken to ensure it is not on concrete or a dirt floor and that it is supported flat on stickers. The stickers allow air to move evenly around and through the pile.
If lumber is left for a few weeks in an unheated area, or a basement without dehumidification, the wood will absorb moisture and swell. When that wood is brought indoors to a heated or air conditioned environment it will lose that moisture and shrink. Lumber, furniture and glue ups should ideally be stored in conditions similar to where they will be installed.
Finishing
Wide boards, glued up solid wood tops and countertops should be finished on both faces as well as the cut edges. Your choice of topcoat is beyond the scope of this article, but a good coat or two of a finish should be applied to the bottom of a glue up or countertop before the top surface is finished.
Installation Procedures
Installations using wide boards, and large glue ups like tabletops and countertops, require extra care and consideration of wood movement. It is essential to use Installation techniques that allow the piece to move with normal changes in humidity. Most wood movement occurs across the width of a board or top. Be sure a counter or top is not locked in place by gluing it down. If using screws, the screw holes in the base should be elongated to allow the screw head to move as the countertop expands and contracts. Alternatively, we have figure 8 fasteners that can work in many applications.
The above is basic information about wood technology. For more information, an excellent article from Fine Woodworking #165 covers the subject in much greater detail. Please note this article requires a trial subscription to FWW online.
This basic information was written by Valerie at Pittsford Lumber and is provided for customers of Pittsford Lumber & Woodshop. Reference Pittsford Lumber & Woodshop and pittsfordlumber.com when copying this work.
