Hardwood Oak

 

Many beginners are thrilled to find pallets made of solid oak (typically red oak). Oak is a highly sought after wood, prized throughout history, for its workability, abundance, and relatively low cost. However, pallets typically spend a portion of their life outdoors exposed to the elements. Red Oak is an especially porous wood. If you take a short section of flatsawn red oak, place one end in a cup of water, and blow on the other end, the air will transmit through the wood and cause bubbles in the water. As such, pallets that have been rained on will soak up the moisture. This moisture can stay in the wood for weeks, even months, after being taken indoors. As with any wood, uneven drying of the grain structure can cause any number of problems (bowing, cupping, kinking, crooking, & twisting).

 

Poor Quality of Wood

 

After being cut at the lumber mill, all hardwood is graded based on it’s consistency. Boards with imperfections like knots, bark inclusions, rot, and grain deviation receive lower grades. The top three grades (FAS, F1F, and Select) receive the highest price and are used in situations where perfect grain structure is demanded. The next three grades (Number 1 Common, 2A Common, and 2B Common) are commonly used where short cuttings of wood can be taken to avoid defects- such as cabinetry, furniture, and millwork. Lumber rated 2A Common must yield at least 50% usable clear wood. The last two grades are Number 3A Common and 3B Common- this is the lumber that is typically used in pallets. Pallet manufacturers will buy these boards directly from the lumber mill. Consumer lumber yards generally have no access to this low grade wood. In order to repurpose pallets, it takes a judging eye and a competent woodworker to sort out the usable lumber from a disassembled pallet.

 

Labor-Intensive Process

 

Still interested in using pallet wood? Assuming the wood has reached an equilibrium moisture content (preferably 5-7% for interior use), it is ready for shaping. Because of the issues that have been already addressed, it is very rare for the lumber to be straight. The correct way to prepare any piece of lumber to be Surfaced 4 Sides (S4S). Lumber bought from the Hardwood section in a big box store will already have been prepared to this standard. Preparing rough lumber requires several large tools that a typical hobbyist woodworker may not own. The process is as follows:

 

1. Run one face across a jointer until straight

2. Holding the straight edge against the jointer’s fence, straighten one of the board’s edges

3. Trim the second edge on a table saw with the straight face down and the straight edge against the fence.

4. The last face can now be finished through a surface planer.

 

Now that the board is S4S, it is ready for use. There are still however complications with pallet lumber. First, the thin deckboards (typically 5/8”) are hard to keep from flexing when the first face is ran across a jointer. By skipping this critical step, there is no true face when the board is ran through the planer. The result is boards that have momentary planarness- any bow or twist in the wood will remain. Second, due to the low grade of lumber, even after boards have been shaped to S4S, inconsistencies in the grain will react to the wood’s internal forces after several days of sitting untouched, even without changes in temperature or humidity.