Grain on Wood and its Effects

Wood grain is an extremely important aspect of wood quality and should be taken into consideration when choosing out lumber for your various woodworking projects. The rings, or grain on wood tells us more than just its age. I suppose we’ve all been taught somewhere in our science classes that each ring represents a year. True. But there is more to growth rings and wood grain than many of us have been taught.

Perhaps you’ve also heard that it’s best to fell lumber during the cold winter season. This is true as well, due to the natural process that trees go through during this period. Trees will build up a hard, darker protective layer over the fresh summer growth to insulate it against the cold. This, coupled with the fact that a tree will draw a large portion of its sap to the base for the same reason, makes for better lumber.

With the bulk of the sap out of the tree, seasoning it won’t take as long, and can be ready for use sooner. Log house builders take advantage of the protective layer that is built up before winter months as it will provide exterior durability to the log as a whole. This of course, won’t matter all that much if the log is going to be ripped up anyway and used as smaller lumber.

Well, going back to wood grain. The grain on wood has a lot to do with how a piece of lumber behaves when seasoned. So we know that seasoning wood is important, but what’s equally important is how the seasoned wood turns out. If the seasoned lumber comes out all twisted up like a drill bit, it’s not gonna be suitable for much – even if it IS seasoned. So what is it that enables a piece of lumber to withstand the rigors of seasoning with minimal shape-change?

As you probably guessed,

Flat-sawn, Except for the 2 Center boards

it’s the wood grain! – More specifically, it’s the direction of the wood grain in relation to it’s cross sectional shape. Perhaps you’ve heard of “quarter-sawn” and “flat-sawn”. Well, flat-sawn boards are what make up the bulk of what you see at home centers due to it being the most economical method. And quarter-sawn boards are the higher-end cuts that you often have to custom order.

Flat-sawing simply slices the log down its length from one


side across to the other, without changing the orientation of either blade or log. Obviously, this has very minimal waste. Quarter-sawing is a cutting method that rips a log into quarters initially, then proceeds to cut each individual quarter in a “wedge” point down position, the blade ripping through vertically. This method produces significantly more waste due to it being quartered first.

So as you can see, looking at the cross section, the grain or annual rings on the quarter-sawn boards run perpendicular – or close to it – to its faces, and those on the flat-sawn boards run an arc almost parallel. These grain relations to their prospective faces are what gauge a board’s stability – or lack of it. Simply put, the more perpendicular the rings run in relation to the board-faces, the more resistant it will be to shape-change.

Conversely, the more parallel the rings are against the board-faces, the more unstable the board will be, and the more likely it is to warp in some way.

(Images: courtesy of Clker Clipart, & Wikipedia article Quarter sawing.)

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