you are clamping too long 

Great video!! Here's my theory. When the clamps were removed after 30 minutes, the glue hadn't cured enough to compensate for the release of pressure. The boards pulled apart just a little bit on their own and messed up the glue. When you just pushed the boards together and left them, there was no change after 30 minutes, so the joint was stronger. Maybe?

I was a research engineer for 10 years designing and carrying out experiments, and a woodworker since before that. This is one of the most complete and robust scientific woodworking experiment videos I've seen. Controlling for all sorts of variables via sensors that most others would ignore. Thank you for this video, I and countless others will benefit from your rigor! I'm about to glue up a large table in half a dozen glue ups and this will save me days!!

As a mechanical engineer I applaud your approach and execution. As a long time wood worker I just found the answer to a question I have wondered about for 50 years. Congratulation, Suman, you deserve a big thanks.

I worked in a furniture mill in the early 1980's. When making raised panel doors with standard stick and cope construction, our rule was to leave the doors in the clamps for at least 2 hours. After that time, they could be removed from the clamps and stacked if we needed the clamps for another batch of doors. (We typically made doors in batches of 50 to 100 doors.) We were using a typical PVA glue, something similar to Titebond Original, which we bought in 55 gallon drums. We let the doors cure for approximately 24 hours before doing any additional work on the doors (trimming to final width and length, putting an edge profile on them, sanding, etc.). I follow the same practice in my shop today. I leave a glue-up in the clamps for at least 2 hours and don't stress the joints for about 24 hours. I've never had a glue joint fail when following these procedures. (Except for the time at the Furniture Mill when someone stored a 55 gallon drum of glue outside, overnight, in sub-zero temps. None of the joints made with that glue held! PVA glue is ruined by freezing.)

My rule of thumb from a practical and time efficient standpoint was to clamp up in the evening and let dry overnight then release and carry on the next morning. Has worked for me for decades.

Great info. I think one important point was unstated or understated: the piece without clamps was not disturbed. We saw how little force was required to break the joints when the glue had not dried yet. Clamps hold the pieces together so that they don't come apart from something as minor as bumping the table that the glued pieces are on. Edit after watching again: the proper testing would have been to clamp for 1, 4, and 12 hours - then waiting to test until the glue had cured at 24 hours. While 30 minutes was shown to be too little, it was not shown what happens at 1, 4, or 12 hours. The assumption that 4 hours is enough is merely assumed.

Testing that actually uses multiple samples and throws out the top and bottom? Here on RU-vid? Amazing! Seriously, I find it so refreshing to see a real effort to apply the scientific method. Thank you! (I've wanted countless woodworking videos here, but this is the first of yours. I subscribed.)

Love your scientific approach to woodworking. We need more channels like yours. Great info with practical uses. Thanks for your content.

Id like to see a follow up on this video on what is the minimal amount of glue needed to secure a joint vs drowning a joint.

my hypothesis on the 30m clamp 24hr dry boards is that the clamps force much of the glue out, but the bond after 30m isn't enough to the adherants to maintain the joint and so it weakens. i've had this type of result when overclamping joints, wiping up the squeeze out and then backing off some of the pressure. i had a tabletop split right down the glueline this way and ended up doing some testing to figure out why it might have happened. i found it was pretty well understood that too much pressure can starve a joint and i suspect that backing off the pressure after clamping is creating a similar situation.

Great vid, I’m sure this will be very useful and informative to a lot of people including myself! My totally unscientific thought on the 30 min/24 hour surprise breakage is that maybe it could be that when the pressure is released before the glue is fully cured, the wood slightly ‘rebounds’ when the clamp is removed and causes a sudden shift in force that might upset the bond, whereas an even pressure scheme for the entire cure time wouldn’t experience such disturbance in the forces and glue line. Just a thought for future vids - it would be nice to have a text layover of the test conditions (clamp time etc) during the part of the video where the breakages occur in the testing. Good for easily distracted people like myself to see where we’re at. Keep up the great work, I love this channel!

I'm glad that I can safely free up my clamps in shorter intervals, since I started woodworking I'd usually leave glue-ups for 8 hours. Great video! The pacing of information throughout was perfect.

Your videos mix engineering and woodworking in a way I haven't seen done on youtube before, really enjoyed this. Keep it up!!!

Love how thorough you were with this. You have saved me from the worry of "Have I clamped this long enough" I was at overkill with overnight glue-ups lol. Thanks Suman.

By clamping you push excess glue from joint. When you remove clamps after 30 minutes you release pressure on wood so a little tiny gap can occur on joint, but there is no glue to fill that gap. So it doesn't matter that you leave it for 24 hours, joint is already weak. When you making joints using just hands or weak pressure, you don't push so much glue out from joint, you don't store tension in wood, so wood don't try to break that joint and glue can do the job. There is probably a little more glue in such joint but it doesn't matter.

I watched this after seeing the joint testing video you did with Scott Walsh, and you've definitely earned my subscription! I only own a few clamps and I'm definitely one of those who leaves them on overnight if not a full 24 hours so knowing this will help ease my anxiety about taking them off sooner. Thanks, and I look forward to seeing more of your testing videos!

I am so glad you did the hand test, because I cannot tell you how many times people have told me 'you should clamp that'. I usually just use tape on veneer repairs (small pieces) unless it may shift. Its always been fine. Thanks for the video!

This is an excellent video on glue ups. I usually wait at least 1 hour before handling or working with glued material on fast moving projects, but now will wait longer after seeing you video. Thanks a million

This is a super helpful video ! I didn't realize how much risk I was taking unclamping my glue ups at 30 minutes. You've probably saved many people at least one project disaster. Very through analysis !

Wow, heck of a video on wood glue. You answered a huge number of questions I’ve asked myself, clamp time, fit, etc.. Great video, thank you. Looking forward to your next vid, you a great job at explaining what you’re doing, why, and the editing is very good. Thank you, a woodworker from Missouri.

Great job covering the variables I've wondered about every time I am waiting on glue ups in clamps. Nicely done Sir.

Short, concise, expert advice. Thank you. This will be my procedure going forward.

I love the scientific approach you've brought to your channel. There are so many possibilities for things to test in the shop, I always look forward to what you'll test next!

Thank you so much for this test. As a new hobby woodworker this is the kind of video I love.

such a great video Suman... i definitely learned a bit. your approach and execution of these tests is nothing short of amazing.

Congratulations on your very carefully controlled methodology, I hate testing videos that don't even care to make sure the samples and force applied are as equal as possible, it made me really happy to see all the care you put into this, it doesn't go unnoticed.

Thanks for taking the time (and resources) to do that! You just answered questions that I've dwelled on countless times.

Very very informative! You answered nagging questions that I’ve had for decades! No more overnight clamping for me!

Love your scientific approach to woodworking issues. Very professional and informative. Keep up the good work.

Outstanding! Thank you so much for investing the time in doing this and sharing the results!

Great video, and I always appreciate anyone who tests conventional wisdom to see if it really holds up. Some years ago I was doing a project of making wood covers for baseboard heaters. It was all made out of poplar but required a ton of glue ups. But all of them are under low stress. I found that just holding the pieces together with my hands for 5 minutes was sometimes sufficient. 4 years later none of these glue joints have failed. Typically, I prefer to leave major glue ups in a clamp for 8-24 hours. But for minor things, where the wood will be under low tension and not see serious abuse, then shorter clamp times work just fine.

OH MAN. This is the deep dive I've been waiting for. Thank you for this!

This was enlightening. Congratulations on your method, the editing, the data collection and everything. Awesome work

As an owner of a WW business, (and an even smaller YT channel than yours...lol) this is very helpful information. I got into the habit of writing the time on my glue-ups and waiting about 3 to 4 hours with only enough clamping pressure to get squeeze-out along the entire edge. As to the LAST TEST...my theory would be that the initial pressure squeezed out most of the glue and then releasing that intense pressure left the joint a little "glue-starved" for final curing.

Thank you for putting in all the time and resource's to show us the results. You have triggered me now to try my own tests on the rub joint of old, I think this may be interesting.

First time watching one of your videos, and I have to say this was not only a really useful topic but a brilliant approach/process to testing Really really useful, great stuff

Amazingly detailed video. This is going to save me so much time (and clamps) for future projects. Thank you Suman!

Perfect timing, I got some sheet goods to laminate this week. Thanks for all the helpful info as always!

Good video Suman. Appreciate your hard work and resources + efforts you put into these videos. Keep up the good work. Looking forward to more such content from you.

As an engineer myself I have to say: Perfect execution! 🤩I love how you put attention to all the details! And the results are also very helpfull ... thanx for investing your time. 👍

Removing the clamps before fully cured likely allowed some spring back to cause fractures in the semi-cured glue joints.

Great video. Very informative. The non-clap results were very surprising to me. I'm going to think twice when I do my next picture frame...I usually struggle with a complex set of clamps trying to distribute equal pressure on all sides

I love your perfect explanation of a well executed scientific process. From observating your experiment, I am smarter now than I was before.

I just LOVE theses kind of test base video where we get to conffont our habits to rigorous testing method and growing from that new knowledge

This is honestly one of the best videos I’ve seen. Very informative. Keep up the good work!

I loved your scientific approach to woodworking! Your channel has a lot of potential!

Saved me a pile of testing , thank you. I am also sharing because I think someone who takes the time to do testing is a valuable asset to any wood workers out there.

Bravo, sir! This is an excellent approach to the scientific method--you control for the things you can, account for extremes in deviation, and publish your results in an easy to understand way while acknowledging constraints. I'll definitely be reducing the clamping time between phases now that I understand this. I mostly make picture frames and smaller jointed items anyway. If something is clamped for 24+ hours, it's not a big deal, but I won't worry about the joints being too weak after 2-4 hours, so long as no additional stress is added in that time.

Love the process you used, I'm 60+ years old and spent my life thus far as an engineer asking the questions you asked. Well done! About to retire and spending more time in the wood shop, been thinking about my glue ups, hum... and you just did 700% of the work. Thank you so much. Youre awesome, thank you. Honestly, I think you out engineered Tightbond on their instructions, and you were very graceful, well done.

Yes! You make valuable, quality video, Suman. Doesn't matter if they don't come out often. Good stuff is worth waiting for, and it can only come as you are able, not as others wish. Very helpful to quantify the time effects of clamping glue-ups. Adequate clamping pressure, released at 4 hours but NOT disturbed for 24, and on to the next tasks. It would make sense to have left them all for 24 hours as directed, to see if it matters when the clamps were removed. I suspect it wouldn't matter so long as the glue lines were intact. You are so right that the quality of the edge match is most important. And that means you don't need a clamp every 3 inches either. I glued a 3 piece panel of cheap wood with jointed edges for a painted sign that rotted away after 15 years in the rain, snow & ice. But it never came apart. Thank you so much!

very thorough attention to details!

Thanks for such a detailed test. 👍

Excellent video! Well presented and thoroughly thought through.

Most of my glue-ups are segmented rings for wood turning. This is useful information to me, especially allowing the joints to cure for 24 hours. This will speed up my assembly process while still producing a strong, safe bond.

great video and even greater experiment and explanation, thank you very much for taking the time to do this 😃👍

Fantastic. Limited variables to 1 at a time. Love the thought out testing methonds. Just fantastic

Really great testing scenarios, demo process and videography. Some amazing and unexpected statistics too. Well done sir!

I have a video suggestion for your test rig. It would be cool to see testing done to compare fluted dowels, spiral dowels, regular dowels, and maybe miller dowels too for the fun of it. I'm curious if the friction of a regular dowel causes glue starvation, or if the different types of dowels cause any significant difference in strength in the joint. I've never seen anyone test this before and many woodworkers use dowels in their joinery.

Very helpfull in my current job, As a lean manager in a Staircase maker. U also saved me Weeks of testing 🙂... I'm already full of new ideas !

Loved this, super informative and you covered all the things

Such an informative video, thank you!

Awesome detail! Thanks for exploring this topic. I can work more effectively now.

That was really well done. Thank you, you answered a lot of questions that I've often pondered.

Wow! No fluff, only the good stuff. Literally packed a 30 minute video into 10 minutes. Played at 1.5x that's less than 7 minutes! You won't find a video packed with more info per minute. Took me longer to write this comment than watch the vid - very well deserved. How could I not subscribe? Genius! Thank you man - been prayin for vids like this!

I love Titebond III. However, I have believed - from my woodworking experience [I used to be a luthier] and am now a woodcraftsman - that it is weak unless it is left undisturbed for 24hrs. After then, it is an excellent bonding agent, and as you have shown, only 4hrs is necessary for reliable strength. But good to have your scientific experiments to draw from, really appreciate it. Great work, thanks.

Second video I've stumbled upon from you with good data. Subscribed to make it easier to find your future vids.

Helpful video, thanks!

I've seen a couple of your stress tests and I have one compliment on your test setup. A lot of videos that I see people doing similar tests they use a luggage scale and try to capture the readout with a camera to find the frame with the highest reading. Your setup is much better because of the peak-hold feature of your scale. LCD displays, especially on inexpensive luggage scales have a fairly slow refresh rate so the actual peak reading may never show on the LCD. The peak hold of your scale will actually capture the peak reading even if it happens between LCD refreshes. Thank you for the quality of your test setup.

Great info, you saved a lot of extra glue time, and clamps. I always wondered about using tape on glued miter joints, now I see some proof thanks to you.

I love this video. This is such a great idea, and really well-executed. Such valuable info

Awesome video! Thank you so much for the hard work and fantastic video, as always.

This was an interesting video! I liked how you did 5 samples per test.

great video! Thank you for your effort!

Amazing effort Suman, loved it and it is much appreciated.

Great video as always so much great information with scientific testing to back it up in a small way. Thanks for sharing

Very informative video, great tests and a lot of knowledge as a take away! Thanks! :D

love this. Lots of good information here

Awesome video! Well put together, concise, great info and well thought out experiment. Glad it popped up in my recommended, will check out some other videos on your channel! Thanks for producing it.

Nice well paced presentation with excellent test based info on glue/clamping strength relationships. First time on your channel, wil be back to learn more. Thanks for sharing.

Excellent job. Very useful information. Thanks very much.

Excellent video!

Wow, what a good video. As someone who has worked in destructive testing for years, your methods are pretty much as spot on as possible given the variables in material. Now, next task (for me, at least) would be to determine the optimal amount of glue per square cm (sorry, am in Europe so we use metric) for the Cherry used. Then compare that to less and more porous timbers. I see a whole series of videos here!!

Love the content, Suman! You’re answering a bunch of the questions a lot of us have been asking ourselves…… overnight in clamps it is 😅

Brilliant presentation! Wow. Excellent video

Very informative! Thanks for your efforts.

The video we always wanted! Loved it!

Nice! Will definitely speed up some of those clamp dependent projects!

This is how a science of woodworking video is done. Thank you for being a hero.

Man that was a well Conducted test. All controls were controlled and the test rig was an excellent setup! Kudos!

Thanks for an excellent video.

Wonderful video as always, Suman. I am always skeptical of the times listed on the bottle and tend to leave them for at least a few hours. Thanks for the work you do confirming that!

Hi Suman Very cool that Scott collaborated with you. You are our scientist! Thank you Ed😊

Was looking for a thourough glue clamping time video. This is great man! I don't ccomment much, unless I feel like I got great value out of a vieo. Really liked the video. Well put together! Subscribed.

Thank you. This has been super helpful!

This is great! Your methodology is appreciated and earned you a subscriber. I'm looking forward to looking through your other content.

Great work Suman! Very interesting and helpful!

Thanks for the information. Very useful.

Love your videos brother ❤🎉🎉 yes testing is real hard work it demands patience, understanding science and lots more. Really appreciate your work👍🏻👍🏻👍🏻🤠

Good info! I know a lot of time, effort, and thought went in to your presentation. Thank you for it and best wishes for success in your endeavors. When pressed for the need of clamps, my minimum time has typically been two hours but, when it's an option, I prefer, at least, overnight clamping.

great attention to all the testing details!