Reader Dave Raeside writes:
In one woodworking course that I took the instructor said that he is no longer using kiln-dried wood for his projects, but is only using air-dried lumber. In another course the instructor said that he only buys so-called “rough and ready” lumber for his projects. And, recently I read that one should not use so-called “S2S” lumber. But, another of my woodworking instructors sees no particular issue with “S2S” stuff, as long as you buy it thick enough to “re-mill.”
So, what’s a fellow to do?
Your question is a great one. My answer, however, will not be definitive I’m afraid. I think it is, for the most part, a white wine vs. red wine question.
There is great advantage to using air-dried lumber in some cases. Some species, such as walnut and redwood, are steamed during processing to migrate some of the color from the heartwood into the sapwood. The result is that the boards have less color overall. I think steamed walnut looks rather flat when you compare it to the air-dried stuff.
However, air-dried wood is less likely to be stable and acclimated to its environment because of the unpredictable nature of the drying process. As a result, you need to be more careful about moisture content when using air-dried wood. Check its moisture content carefully to ensure you don’t have any surprises ahead.
You also need to be more careful with air-dried wood when it comes to mold and fungus. Kiln-drying kills these organisms; air-drying does not. Also, when it comes to softwoods, kiln-drying will crystallize the wood’s resins, making the boards less sappy and nasty on your tools.
As I see it, the rest is up for debate. The kiln-drying people say their wood will have fewer drying defects. The air-drying people say they can get the same yield when drying is done with care. The air-dried people say their wood is superior in that the kiln-dried stuff has a “dead” feeling. I’ve never experienced this, however.
I work with both. Instead of judging the wood by the process that dried it, I judge the wood on its grain, figure, defects and moisture content. If the boards meets all those criteria, I’ll buy it and use it.
On the subject of rough lumber v. S2S or S4S, this is a question that is more about your tooling and your time.
You’ll save money if you buy rough lumber, but you’ll need heavy-duty tools to process it and allow more time in your schedule for processing. You’ll also face more surprises with rough lumber (both good and bad) because beautiful figure and ugly figure can be obscured when the board is in a rough form.
If you buy surfaced stock, you’ll be better able to judge the figure of what you are buying and it will take less time when you are processing it, but it will cost more and you do need to be more concerned about warping, twisting and bowing. Surfaced stock that has been poorly processed or stored will be more warped. So buying over-thick stock is a typical fall-back position.
So this debate also comes down to judging the stock in front of you. If you are looking at rough stock, you need to develop an eye for picking out good figure in rough material. If you buy surfaced stock, you need to be acutely aware of twisting and warping. And you have to consider the time factor.
– Christopher Schwarz