I work mostly with Titebond and I was wondering how long it’s proper to allow the joint to set before stressing it. The only instructions the bottle gives are to clamp for at least one hour. I was taught to allow the glue to set up for about a day before I could stress the joint, but recently I’ve become more daring. How short a time is possible? Is the strength of the joint permanently affected if the joint is stressed too early in the setting process but does not immediately come apart? Though I’m talking mostly about Titebond, I’d be interested in other glues as well.
Also, and I know this may be a matter of personal preference, should you apply glue to both sides or is only a one sided application necessary? I’m referring in this question mostly to panel glue ups and laminations, but I’d be curious about other joints as well. I’m sure there must be some great glue failure anecdotes out there, and I’d just as well like to know how safe I should play it.
Thanks,
Tim
Replies
Not sure exactly what you mean by "stress the joints". That could mean dragging a two hundred pound buffet across a hardwood floor, but I suppose it does not really matter.
I would treat any project very gingerly for the first 24 to 36 hours after glue-up.
Tim:
I use Tightbond here in the shop for all my woodworking operations. I do not like the poly glue but have used it on special occassions for special projects. My choice of glue is Tightbond. Living in the southwest where temperatures can reach 120 in the shade, I shut down my woodworking as I find that the glue sets up so rapid that I have little time to clean any squeez out.
When I clamp a project, I leave the clamps on for a few hours or overnight. I do not stress the joints for at least 24 hours to allow the glue to cure. I am no expert with Tightbond and I am sure that if you log on to there web site you can send them a e-mail with the same question regarding stress and they will supply you with there answer.
Good luck and stay safe:
The Old Timer
A Franklin rep once told me he knew of production shops that unclamped pieces glued with Titebond II after 20 min and continued milling. NOT a recommendation, just an anecdote.
I once edge glued a couple of boards with Titebond. 30 minutes later I decided to take them apart because the surface was not as flat as I wanted it. I could NOT separate them without using the saw. That said, I always keep the clamps on at least 2 hours and don't stress the glue-up for 24 hours.
I use Tite Bond all the time, and I usually clamp the pieces overnight. However, I recently made a cutting board, and I took the clamps off after 12 hours. I tested a cutoff for strength, and it broke the wood, not the joint. So, I suppose that indicates that 12 hours is enough. But that was a cutting board (not much stress). If you have the time, why not let it set a full 24 hours?
By the way, I used Tite Bond II (waterproof) for the cutting board. I like it a lot, and I'm thinking about using it more in the future.
On your question about glueing both sides or just one side, I've seen different opinions. I always glue both sides ("members"), and I've never had a glue-up fail. Also, I make sure to put a fairly thick layer of glue, let it set a few seconds, then clamp.
Edited 7/22/2002 9:10:11 AM ET by MattSchenker
There are three "times" associated with all adhesives. Open time is the time associated with how quickly the adhesive sets to a point where it no longer should be used for a satisfactory joint. The next is "clamp time" or the time that the joint should remain under clamp pressure and the final time is the ultimate "cure time" which is where the joint has developed 90% or more of its full strength.
All times are significantly affected by temperature, humidity, and the moisture content of the wood so definitive times are not possible. However, for PVA adhesives, clamp time is typically stated on the product directions as 20-40 minutes after which about 25-50% of the strength has developed and the clamps can be removed. But, no heavy machining or sanding should be done at this time. Cure time for PVA adhesives is typically 24 hours for developing about 90% of ultimate strength and machining operations should not cause a failure. Again, cure time is generally stated on the container.
There are any number of other adhesives and their characteristics are all different. Buy a copy of the "Glue Book" published by Taunton Press for a complete discussion of this subject.
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