What's the big deal about a glue line?Originally Posted by Steve Schoene
Contributor
What's the big deal about a glue line?
"Anything seems possible when you don't know what you're doing."
Member
I avoid glue lines. Do do so takes a lot of work.
If you can see one, other than at the place where grain changes a bit between boards, you are producing sloppy work. Often that’s ok depending on the use of the object but not always.
Member
Finish both sides equally. Screw it down. As long as it doesn't warp the leg system don't worry about it.
[OP]
Member
Glue lines are inevitable and impossible to avoid, usually. I’d like to make the glue line as unnoticeable as possible though. For me, a glued panel should look cohesive, rather than obvious and abrupt changes in grain direction or color. Just personal preference I guess. I’d like to look at the top of this table and see a 15.25 by 48.5 top, instead of two 8 inch boards glued together.
Contributor
Ripping a board and gluing it right back together should not produce a noticeable glue line as the grain pattern is virtually uninterrupted.
"Anything seems possible when you don't know what you're doing."
Member
To me, glue lines should either be a) almost impossible to find, or b) obvious.
As in most design elements, contrast is fine, and invisibility is fine, but where you run into trouble is all the grey area in-between – particularly where it appears the builder tried to "hide" something, because "hiding" suggests "mistake."
One design element that calls attention to itself is putting a kerf on the edge of a board where it butt-joints another board at 90°. Somehow, the joint looks crappy without the kerf, but with the kerf, it throws a shadow that says, "Yeah, I'm just a lowly butt joint, and that's all that I'll ever be" – but it just looks "right."
In a way, it's analogous to color: Matching colors are fine, complementary colors are fine, and contrasting colors are fine – the trouble lies in where it appears someone tried to "match" colors and failed miserably.
In my opinion, most beginners are better served by either calling attention to, or at least ignoring, the inevitable discontinuities in woodworking rather than by trying to "hide" them. I call it the "Plastic Wood Corollary." I'd much rather see a sunken nail head than that miserable material, ever, anywhere, except under paint.
But...that's what it is, isn't it? If you wanted no discontinuities or imperfections, why didn't you go with Formica or plastic or metal? Just kidding...but you see what I'm getting at. Sometimes you just don't have enough material to find a way to arrange the boards such that you can make ALL of the glue joints invisible. In such cases, I'd rather see ALL the glue joints be obvious, rather than just ONE, again, because ONE mismatched glue joint is more of a discontinuity – and looks like more of a "mistake" – than ALL of the glue joints being mismatched. When they are ALL mismatched, it tells the viewer "the glue joints don't matter." Which they don't.
Last edited by Jacob Reverb; 01-05-2019 at 8:22 AM.
Contributor
It's nice if you can find wide boards to glue up a side or top from one board, or boards cut from the same log, but it isn't always available at reasonable prices. I made a piece from walnut that came from some wide boards from the same log and depending on the light and the direction you are looking, some parts have a different darkness or lightness and contrast. I'll still take unstained lumber with a clear finish over stained every time.
Managing pieces for equal moisture exposure is a constant battle while in the building process. I either sticker after processing, or if I stack up some panels on a table, I put an impervious surface on top followed by something for weight. When I was a beginner I underestimated the importance of bringing wood inside to acclimate as well as managing storing project pieces from initial planing to glue up and finishing. (Often with unpleasant results!) Live nd learn......that's the interesting part of it all!
Member
Glue lines are not inevitable and, with solid technique, can almost always be avoidable. Just running the boards for several passes over the jointer is seldom enough. After the initial edge straightening and laying out the boards for the most desirable grain patterns, clamp one board vertically, with the edge to be glued, on the bench. Then lay the next board on that. In a darkened room, shine a light behind the two boards. You will almost always see some light between the boards. Mark any places with chalk any places where the boards touch. Then, with the jointer set for a fairly light cut and with a carefully squared fence, lower the boards onto the jointer to make a short cut in the area around the marked touch point. (You are likely to notice a minor grain anomaly in that area.) Then make full passes with the same jointer setting. Retest for a light tight joint between the two boards, when held together witha light hand pressure. When you can pass that light tight test for all boards you are ready for the glue up. Put glue on both edges and clamp with really firm pressure.
Member
I would do what I have done successfully, rip the board down the middle and glue the halves back together with the bows opposite each other. The seam will be acceptable.
Contributor
I know some would consider it cheating, and may not work with your design, but I've used 1/4" birch quarter-round to cover gaps like that. I've also added thin wedges of wood on top the apron to fill the gap, but thats a lot more work.
Member
Hmmm...it appears that we are talking about two different issues here.
When I saw the term "glue line," I thought someone was talking about the grain/figure not "matching" between adjacent pieces in a glueup.
I now realize some people are actually talking about GLUE lines ... where you can actually see a layer of glue between boards. I've only seen glue lines once, on a bar top that my landlord had glued up, apparently without any clamps. I agree that looks terrible and screams sloppy (and usually structurally unsound) work.
IMO, the former issue isn't an issue, but the latter issue is unacceptable...
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