Is there a standard definition of what it means to S2S?
Standard technique to get 2 faces surfaced is to joint an edge, then
joint a face, then plane the opposite face. Thus to S2S such that a
board is flat, you've really S3S (or S2S1E as I've seen used).
Seems to me that if you just S2S you've got 2 faces parallel but the
board isn't necessarily flat - it could have a bow or twist that isn't
removed by planing the 2 faces.
So what I really want to know is ... is S2S lumber flat enough for
precision work without further flattening, such as to make a picture
frame or cabinet door frame? If not, is S4S any flatter?
Surfaced 2 Sides. Usually means planed both sides.
If you want your lumber jointed, you must specify it that way, and likely pay
a good bit extra. S2S does *not* mean jointed on one face and planed on the
That is correct. For that reason, I buy my lumber rough whenever I can, and
joint and plane it myself.
Why would it be? That just means the edges are approximately straight, and
approximately square to the faces.
Doug Miller (alphageek at milmac dot com)
How come we choose from just two people to run for president and 50 for Miss America?
Yes, maybe, sort of. Coming off the planer at the mill the wood may be
perfect. After sitting for an hour or a month it may move.
Probably everyone here can tell you a horror story of how wood looked
perfect, but went to hell overnight. I bought some a few months back from a
very reputable source. They planed it to thickness for me and it was
perfectly flat. Got it home and ripped the edge to get the width I wanted.
Nice flat wood, ready to use. Had my lunch, went back to cut it to the
lengths I wanted. Nice big split right up the center of the board.
Bought some S4S to make a bookcase. Cut the length I needed and finished
for the day. Next morning you could have used the boards to make pipe as it
was curved that much. It was stored in an outdoor shed where I bought it.
I moved it inside.
...The wood is roughsawn and banded, or
dimensioned and then banded. The wood can
warp, twist, cup, etc. but if it has been surfaced
to S2S the surfaces, no matter how distorted the
board is, are parallel....
...Yes it is, and no it's not. A little quick lesson
here. Wood has a specific cut: "To grade", and
"Through & Through". The wood is then hand graded for grain, figure, color,
and defect. At
this point the wood is usually still flat. The wood
is then surfaced to grade: "Hit & Miss, S1S, S2S,
S3S, S4S, SS-PTS, finish (the later two are
plywood grades). Not surfaced is called rough
sawn. The grading can also take place after
the wood is surfaced, and just before it is
packaged for delivery. Depends on the mill, how
they process, age of the mill, size of the operation.
The wood can then be air and or then kiln dried.
The wood is dried by weight to a specific
moisture content, when drying, it is stacked,
stickered, spaced, and banded. The period of
initial drying subjects the wood to much tension.
The banding is to keep the wood from distorting.
As the wood dries, it shrinks and the banding is
thus loosened. The movement at this point is
reduced, but the wood still prone to distortion.
A surfaced board can distort but still be parallel.
My preference is to select my trees, assist the
sawyer and cut for grade. Air dry to about 25%
(I live in the desert). The wood can then be
further dried to 12% in a solar kiln. A solor kiln is
not used comercially because they are too slow,
however, they heat and then cool. This daily
cycle help relieve the internal stress in the wood.
This makes it possible to keep degrade as low as
3% (yes, really!).
By air drying the wood myself, I can set the
thickness of the spacers and stickers to determine
how fast the wood is to dry. I can also keep
checking the wood for weight and shrinkage and
keep tensioning the chain binders. This helps
reduce degrade. The advantages of processing
my own wood are that I know exactly what wood
I have (ever bought Honduras Mahogany? You
may have bought H.M, but were actually sold
African Mahogany). I can also select the cut, and
dimension. This greatly reduces waste as I get
the wood sized to the projects. Strict control
over the drying gets me a better wood. Usually no
case hardening (though I have had some problem
with Black Walnut) or internal stresses. Also, the
cost is much lower. The down side is that I need
a way to fell, transport, cut, dry, and store the
material. This all takes time, knowledge, tools,
and space. I also need the knowledge of how to
grade if i intend to sell any of my private stash.
To finish answering your question, no, S4S is not
any flatter. That is a matter of wood movement,
not surfacing. "S4S means Surfaced 4 Sides".
If the surface is dimensioned, it is dimensioned. If
it distorts, it distorts.
To me it is always better to select and process my
own wood, but then I have the background (the
lumber industry, followed by the construction, and
then millwork industry) and the resources. Most
of my fellow woodworkers are stuck with lumber
yards or worse yet the big box stores with high-
priced wood that is processed to look saleable,
and generate the highest dollar.
Just my 2 cents...
You have lots of answers already. I'll give you the simple answer I don't
I don't have a planer or a jointer, and my skill at surfacing with hand
planes is such that I really try to avoid having to flatten the entire face
of a long, wide board by hand. I can get it pretty close to flat, and get
the opposite faces pretty close to parallel, but I'm much better off to
leave well enough alone and use it straight from the mill as much as
The wood I get is S2S, but the faces are only barely planed. To get a
smooth board, I have to shave a little off. I prefer to do this *after* I
have cut what needs cutting and have done almost everything else, and I
only plane what needs planing. (For example, I leave the insides and
bottoms of boxes semi-rough, since I'm covering them with velvet anyway.)
I've found that the key to this game is *careful* lumber selection. Every
board has a slight (or pronounced) warp or a twist or a cup in it
somewhere, but if I'm very, very picky and spend a good 45 minutes going
through the entire pile, sighting down every board from both ends, laying
them flat to see if they rock, I can almost always find what I need.
So far, it's worked out fine. I adopted this practice, however, after
making the mistake of buying a really pretty board that was twisted a
little to the left at one end. Danger Will Robinson, danger! I used this
board to make some large poster frames. The frame pieces were all about 1"
wide and up to 40" long. A great many of them started curling toward the
kerf on the far side of the blade, and I was very grateful I had my
splitter installed that day.
I salvaged the frames, but it was an ugly business. A couple of the posters
are nailed to the wall to hold the frames flat. Ugly. Shameful. Lesson
If it ain't straight when you buy it, it ain't gonna get any better when you
start cutting it up. Get it as straight and flat as you possibly can, and
let it sit in your shop for a bit before you work it up. That way you'll
get some idea what's going to happen before you commit to using it. Even
then, it might start moving on you as soon as you cut it.
Hope this blind leading the blind advice helps. I've only been using real
lumber for somewhere around six months or so. Before this, I always bought
S4S at the BORGs. I never had any of these sorts of problems to deal with
back then, but then again my choices of wood were limited to red oak or
poplar, and all the large boards were actually glue-ups made from 1x2s or
similar. This new stuff is cheaper, better, and of course I'm using walnut
for everything, and hopefully will never have to use a piece of red oak or
poplar for anything again. :)
Michael McIntyre ---- Silvan < email@example.com>
Linux fanatic, and certified Geek; registered Linux user #243621
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