Matters of Grade Importance

Jack Savage | October 13, 2012

With any number of agricultural products—meats, eggs, milk, vegetables, fruits—it’s not always easy for consumers to connect the end product sitting temptingly in the market with the effort it takes to grow and prepare them for sale. Wood products—notably lumber-- are no different. There is more to making a good board than might first meet the consumer’s eye.

We are used to seeing boards everywhere we look—whether at the local lumberyard or on the sides, floors or walls of our homes or maybe our dining room tables. What we might not often think about is how those flat-surfaced boards are produced from a cylindrically shaped tree. It is precisely this process—which involves a fair amount of geometry and no small amount of creative vision on the part of the sawyer—that anyone operating a sawmill small or large must master.

As consumers we want our lumber to be eye-catchingly attractive, but we also need it to have a predictable strength and stability based on the known characteristics of a particular species of wood. How a board is sawn makes a difference.

To that end Purdue University’s Dan Cassens has been presenting a Portable Sawmill Workshop around the region the last few weeks. Cassens, a Professor of Wood Products at Purdue, has put together a book focused on the topic, Manufacturing and Marketing Eastern Hardwood Lumber Produced by Thin Kerf Band Mills. That might sound like a bit of a yawner to some, but there are folks who love to saw wood and a portable sawmill can be a fun way to do it. If you like the idea of using ultra-local wood—sawn from your own property, for example—working with someone who has a portable sawmill is a great way to do it.

I had the privilege of attending Cassens’ worshop in Durham at UNH’s Thompson School Sawmill. Don Quigley, who teaches Forest Technology at the Thompson School, demonstrated their sawmill and edger, and UNH Cooperative Extension’s Sarah Smith provided additional insight into local markets and market conditions for those of us on hand.

As anyone who has purchased lumber knows, both hardwood (oak and maple, for example) and softwood (Eastern white pine, spruce, hemlock) boards are graded for quality based on the extent to which the board is free of knots and other imperfections or “defects”.

Defects can include a long list of those that are natural, such as knots, holes, pockets, shake (a lengthwise separation of the wood which usually occurs between the annual growth rings), seams, pitch streaks, pith, burl or slope of grain. Then there are those that come about as a result of seasoning, or drying, the wood: stain (Blue stain, a discoloration due to a fungus is not uncommon), checks (a separation of the wood between the grain), splits or warp. And then there are those that come from the manufacturing process itself, including skip, torn grain, machine burn, knive marks or wane (a bit of bark or lack of wood on the edge of a board).

And while one man’s defect might represent “character” to someone else, the consumer should know what he or she is buying and pay accordingly. The higher the grade of a given board, the higher price it commands in the market.

But, as Sarah Smith notes, every log includes some low grade lumber. (Wouldn’t it be wonderful if we could just grow trees guaranteed to produce 100% premium lumber, eh?) So the goal of a good sawyer is to get the most number of board feet at the highest grade out of a given log. It’s trickier than it might seem, especially given that the grading is strict and boards have two sides.

Next time you hit the lumberyard to stock up for a weekend project, take a closer look at the boards as you pick them out. And give a nod to the sawyers who made them for you.