how long do you leave the clamps on for TB-3?

[ken masoumi]

I don't exactly where this 24 hour "wait time" rule came from but it has become a common advice for wood glue cure time.
Yesterday afternoon I glued up a few 2"x 1" x24" to make 2"x2" bench legs,Today after 15 hours I checked to see if the titebond 3 (fresh bottle)has dried enough to remove the clamps,the temperature was around 65°last night.
To my surprise some of the glue was still white in the center of the lump where the glue had accumulated . I could poke my fingernail through it and scrape it off and still felt tacky.the rest of the joints are all nice and dry and the glue is dark brown and brittle.

So I didn't want to take a chance and put the clamps back on ,the manufacturer of TB3 recommends (under ideal condition) 2 hours wait time before removing the clamps but if the joints are "stress joints" ,the wait time is 24 hours.

I know I would have been alright had I removed the clamps but that made me think maybe there is some wisdom in that advice to wait 24 hours .
What's your opinion?

[Keith Hankins]

For TBIII I usually clamp for an hour and don't stress for 12-24hrs depending on where the glue is at. If it's complicated glue up that has stress points, I leave it for 24hrs. For instance, if it's a hutch glue up and it's all the corners and panels, then I won't touch it at all for 24hrs to give it time. On the other hand, raised panel doors. I'll pop them out of the clamps in an hour and just set them aside till the next day. So less than 24hrs. It really depends on the application. Also keep in mind the lower the temp the longer the dry time. In the mid 60's yea, it would take some time. For me, I don't leave the big blobs. I glue and have a pan of warm water handy and use the sponges that have the soft sponge on one side and the rough on the flip side (green/yellow combo). They are cheap, and I wipe away any glue squeeze out. It makes the finishing so so much easier to deal with.

[Jerry Miner]

I don't exactly where this 24 hour "wait time" rule came from,.....the manufacturer of TB3 recommends... 24 hours.

You answered the first part of your question yourself

IME those globs of excess glue do retain some liquid glue for quite awhile, but they are not a good indicator of the conditions inside the joint. The glue cures by drying, and the thin glue line inside the joint dries faster than those fat globs. (The moisture dissipates into the wood). Two hours at 65 deg. should be fine.

[Kent A Bathurst]

For TBIII I usually clamp for an hour and don't stress for 12-24hrs depending on where the glue is at.

Bingo. But - I don't have a clock on it - I wait until the narrow squeeze-out bead is plastic enough to lift with a card scraper, and not leave goo behind. That time varies with ambient conditions.

[Wade Lippman]

So I didn't want to take a chance and put the clamps back on ,the manufacturer of TB3 recommends (under ideal condition) 2 hours wait time before removing the clamps but if the joints are "stress joints" ,the wait time is 24 hours.

That's great if you can do it, but I don't have enough clamps and when I have a bunch of things to glue I have to reuse the clamps. Hard to count, but I am sure I have taken the clamps off after 30 minutes at least a hundred time, and have never had anything fail. I have a habit of breaking the trim cut offs, and they never break at the glue line; so the glue up is always stronger than the wood with 30 minutes of clamping.

[ken masoumi]

For my 6.5' harvest table top I had to wait 3 days for TB 3 to get brittle,the oozed out glue at the joints were still soft after 48 hours ,of course the humidity was way up there and I was in no rush.

[Kent A Bathurst]

So I didn't want to take a chance and put the clamps back on ,the manufacturer of TB3 recommends (under ideal condition) 2 hours wait time before removing the clamps but if the joints are "stress joints" ,the wait time is 24 hours.

You always want to recognize that there is significant - VERY significant - input by the manufacturer's legal department on stuff like this.

You could have safely moved tehm after the clamps came off, and planed, scraped, sanded, jointed, finished them, with no worries. None of those "stress" that joint. In fact, in a glue up to make legs, I am having trouble imagining anything you COULD do that would "stress" that joint.

As opposed to, say, gluing up a chair, pulling the clamps, and immediately plopping my 220# fat behind in the chair. That is not recommended.

[ken masoumi]

Thank you all for your comments,I had a feeling to have a glue up failure after waiting a few hours would have been unlikely,I was just too precocious , it will all change with experience since the manufacturer's direction /wait time is vague at best .

[mreza Salav]

For typical wood glues if the joint is not under stress (like a bent lamination) I don't mind taking the clamps off after an hour or two and leave them aside. For panels, I have even machined (planed) them after 4 hours after glue-up. Have you ever tried to break up a glue-up after an hour? You'd be surprised how well they hold after just an hour. I had to break the piece as the joint wouldn't let go.

[Peter Quinn]

For most domestic hardwoods that are porous and on the softer end of the scale relative to the tropical exotics, I'm usually in clamps maybe 1 1/2 hours unless it's a bend lamination, that goes over night. On edge glue ups and joined butts the whole point is not to build stress into the joints, to make them mate carefully and easily. But I like to let things cure before working them. Titebond III is a cross linking glue, this process takes time, like 72 hours time, and it has a lot of moisture in it that needs to leave the wood, certain joints like M&t or biscuits have nice little pockets built in to store glue that has to work out over days. Work it too early, you get creep. Little ridges at the glue line that you can feel and see through a finish. I've just been down this road on some test doors that went through the shop, sprayed a finish too soon after glue up, like 24 hour later, two days later you could see the glue lines. Wait 3 days, sand, spray, no problems.

one place where my clamp time goes up is on dense exotics like cumaru, ipe, jatoba, bubinga, etc. these take a lot longer for the glue line to cure, the moisture just doesn't wick into the wood easily so everything gets extended.

[Curt Harms]

I recall an article though I can't cite the source that tested joint strength after varying lengths of time after glue-up. What I remember is that hard woods glued with PVA (probably TB1 or similar) reached 80% of their rated strength after 2 hours at room temperature.

[Brian W Smith]

Did a glue up this a.m. with TB3 and some gorgeous,4/4.....Q.S., W.O.

Say 8 this morning.It's been clamped and resting @ 40% humidity and 68*.It is now 3 p.m. and I really need to get this part out of the shop but,I am afraid to run it through the machining it requires after just 7 hrs.Call me chicken,haha.

Edit to add,these were freshly jointed edges........which does make a difference IMO,in not only set-up time but in finished strength as well.

[ken masoumi]

Did a glue up this a.m. with TB3,I am afraid to run it through the machining it requires after just 7 hrs.Call me chicken,haha.

That's what I mean, for all we know 5 to 7 hours is plenty but it is ingrained in our minds that waiting longer is better ,,I bet most of us would wait that 24hrs. "cure time" if we could afford to be patient or we were in no rush to finish the project.

[Chris Padilla]

...and it has a lot of moisture in it that needs to leave the wood, certain joints like M&t or biscuits have nice little pockets built in to store glue that has to work out over days.

This right here. Glue ADDS moisture to the wood and it can be localized by, for example, biscuits. If you sand too soon, you could end up with little divots in the wood that look remarkably like the shape of the biscuit you put there because you sanded while the wood was a bit swollen in those areas.

Now to clamp time...yes, they can be removed fairly quickly. However, I like to leave clamps on "overnight" or anywhere from 12-24 hours if possible. That's just me and I'm no pro and have plenty of clamps...usually....

[Lee Schierer]

Glue dries from evaporation. If the glue surface area or thickness is great it will take longer for the glue to dry than it will in a smaller surface area or thin coating. I try to get the squeeze out off as soon as it is rubbery so it all comes off and doesn't smear. I usually leave the clamps on anything I glue at 2-3 hours unless it is the end of the day and then they stay on overnight or until I get back into the shop a day or several later. If the joint is to be load bearing (stressed) wait 24 hours. Repairing a failed joint is no fun.