Gluing

David Johnson

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Carthage,Mo
Any thoughts on proper glue techniques? Is it necessary to cover both sides of pieces with glue? Videos show single side coverage and also double coverage. Make a lot of cheese boards so need good tight joints. Always make sure of squeeze out, but not to much. Seems I can get that on single coverage.. So dingle or both sides?

David
 
Lots of discussion on this.

Sometimes ---- I glue only one side.

Mostly ---- I glue two sides.

Both work.


My philosophy is --- glue is inexpensive - glue up is forever --- WHY, be cheap about it?

Who really cares is one side is good enough?
 
I typically do both sides myself anymore, but have items I didn't do that with that have held up fine. I think as long as the glue gets into the right places and is clamped up correctly it will hold. I've tore apart cabinets that held quite well with just a line of glue in dados, but like Leo said, glue is cheap and might as well do in a way you know every spot got glued.

For glue-ups on nicer furniture, I tend to put masking tape around the joints to mask any squeeze-out. Like others here, I'm getting to where I am doing my finish work prior to glue-up as well. to make that process go easier and not fight glue stains.
 
I usually spread glue on one side of a joint, rub the pieces together a few seconds, then clamp. One exception is MDF, in which case I spread glue on both sides because of its porosity.
 
I've moved to both sides whenever possible. Scott Phillips (American Woodshop on PBS) calls this "sizing the joint" and swears by it, claiming that the glue gets into both pieces better. He also waits a little while for the glue to tack a bit prior to assembly and clamping. This, he states, is a recommendation that comes from one of the glue manufacturers.

On panels I sometimes revert to gluing one side, but rub the joint prior to clamping to insure 100% glue coverage. Like its been said, glue's cheap. Might as well be sure.
 
When I was making a lot of cutting boards, I always went with a thin coating of glue on both sides of the joint. I also used a wet paper towel to clean up as much squeeze-out as I could while the glue was wet. Saved a lot of work later.
 
Try putting glue on one side, clamp, then immediately pull apart. Then decide.

When I am dealing with plywood, it is rare that glue on one side transfers adequately to the other side. I don't even try any more.

If I have a couple pieces of hardwood that I have hand planed to perfect the edge, apply to one side and a quick rub before clamping almost always gives perfect coverage.

If it is hardwood with jointed or sawn edges, the results are mixed, so I often put it on one side, quickly rub the sides together, and fill in the glue on the second side as required.
 
If I am nailing or screwing the joint, I usually put glue on one sice only but I use a lot and have to scrape the residue off afterwards.If I am not nailing or screwing, I put glue on both surfaces, covering all the surface to be glued, let it soak in, then apply glue heavily to one side and clamp it together until the glue dries. I use Lepages Yellow Carpenter's glue, which dries in about 35 minutes, technically, but I wait 24 hours before I do any work on the piece. HTH.
 
Roger opens another issue about glue. Most carpenter's glues (yellow) "dry" enough to remove the clamps in less than an hour or two, but need a full day to cure to full strength.

But there is still another issue. The water based glue introduces a significant amount of moisture to the wood in the vicinity of the joint. If you sand it level, even a day after gluing, the wood still has a higher moisture content, and will shrink over the next week or month, giving a "sunken" joint. I find the problem substantial when I am gluing a hardwood edge to a piece of furniture plywood (due to the open texture of the edge of the plywood), or even when doing a large glue up of solid wood. Therefore I only roughly complete the glued area and leave the final sanding until later in the project.
 
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