All about applying glue

Re: All about applying glue

Barry Irby

I agree with your approach. I like to see both surfaces coated with a thin coat covering 100% of the surface and I like to see a little squeeze out. Excessive squeeze out is a waste of glue, minimal squeeze out is verification the glue is coating the surfaces in the joint and that is useful information.

I think I read in some technical paper somewhere that industry strives to achieve 85% coverage. With the understanding it's 85% of every square inch. Like many of my memories that is in the dim recesses of my brain. I can see if both surfaces were covered 85% and then brought together it would most likely be successful.

Another thought is that the glue presents some hydraulic resistance to the joint closing. On narrow pieces very little force will bring the joint together but on wider joints like your cutting board it's not so easy to squeeze viscous glue out of the joint. On one hand I like to apply a liberal amount of glue to keep it liquid long enough to squeeze out. I find it useful to tighten the clamps from the middle out gently and then again and then again. I find a certain amount of compression. I tighten then about as tight as I can and after a few minutes I can tighten them more. I have scrapped off glue such as Bill's first picture shows and then look again in a few minutes and find more like in his second picture. I do not believe you can get clamps tight enough to "starve" the joint.

(Message Deleted by Poster)

Re: All about applying glue

Barry Irby

What is the wood in the cutting board?

Enough for a dozen cutting boards

wood description

Bill Tindall, E.Tn.

cherry discolored by a hardware store of spikes nearby and a firing range of bullets. . It is the same tree as the cherry I posted earlier showing color difference.

I cut this wood off the end of a 12/4 plank hoping to resaw for desk drawer fronts. Too stained for that application as it turned out.

But I wanted to make a cutting board for someone that has a geographical connect to where this tree grew...so this piece will become a cutting board.

Too much glue

Lee Schierer in McKean, PA

If I had applied that much glue in my 9th grade shop class I would have received an unsatisfactory grade. All you need is a light coating on one surface that creates small beads of glue on each side of the paired boards when pressure is applied. Glue running down the surface wastes glue and creates additional work. As long as the glue is applied and rapidly joined you will get a good joint.

I apply slightly less glue than you applied on one piece and have never had a glue joint fail.

Lee

Re: Too much glue - what I was taught

Jesse Cloud

I took courses at a local community college. All the teachers had industry experience. Those working part time still had their own business.

In the intro course on the first day my teacher said "For now, some squeeze out is ok. But before you finish this class, you will be expected to be able to make a strong joint with no squeeze out.

In the first week, we edge glued two pieces together and let them sit for 30 minutes. Then we pounded them with mallets until they broke. Not one piece broke on the glue joint. We did the same test the last week with no squeeze out.

I am grateful to that teacher, Bob Mayes.

Glue Squeeze-out

Steve Elliott

How much glue squeeze-out is too much or too little depends on the nature of the joint. When edge gluing like Bill was doing, I like to see little drops of glue about the size of pinheads. I want to be sure the glue has reached the edge so no voids will be left which might show up during staining and finishing. The strength of the joint would be fine with a little less glue but since the faces of the panel will be planed or sanded after glue-up there's no downside to having a small amount of glue appear at the joint line. I try to avoid drips that will run down the surface of the panel if it's stood up while drying.

When assembling a case with a finished interior I want NO squeeze-out on the inside but I like some on the outside where it won't show or can be cleaned up. No squeeze-out anywhere makes me think the joint might not be strong enough.

When assembling dovetailed drawers I've been able to get no glue showing on the drawer interior but enough on the outside that any possible void will be entirely filled with glue.

Thanks, I was struggling with the ID & PS

Barry Irby

It shows up looking about the color of poplar on my monitor. Couldn't imagine you making a cutting board out of poplar.

PS, While I am not in favor of wasting glue, it makes no sense to me to be stingy with glue to the point you worry about starving the joint. We take expensive prized wood and process it with hundreds or thousands of dollars in tools and the hand tool guys put years of training and finely tuned tools to work producing excellent joints and even if they are sloppy with glue it adds pennies of maybe nickels to the cost of the project. Even if clean up adds time it may be offset by the speed of application. Maybe you should apply less glue, but the amount that makes you confident.

Re: All about applying glue

Walt

I recall reading something from Franklin International, manufacturers of Titebond. They said the optimum glue joint would be 1 molecule thick. I doubt many of us are capable of producing a surface smooth enough for a 1 molecule glue joint but their point is that it doesn't take much glue to produce a very strong joint if the mating surfaces are well prepared.

correction

Bill Tindall, E.Tn.

It is curious how the original post that focused on how to apply and spread glue has morphed into how much glue to apply. My answer, had that been the focus of the post, would be more than enough so that any error in the amount applied will still result in enough. The joint used to illustrate application, and overlooked by the nit pickers, is a good target.

As a thought experiment, and an idealized picture of a glue molecule, it would take 3 molecular layers for the minimum- two to coat each wood surface and a third to tie these layers together.

As a practical matter wood is porous and the surfaces will not be perfectly flat. Enough glue must be added to fill the gaps and the pores. Some squeezing out is a measure that sufficient glue has been applied.

you failed to grade the other joint

Bill Tindall, E.Tn.

I'll blow it up for you so it can be better evaluated.

Indeed as was stated in the original post, whose intention was to provide a tip on glue spreading, excess glue was employed on the cutting board blank. Upon curing this 2 cents of wasted glue was removed with one pass of a paint scraper and the blank planed smooth. The interior was routed away, free-hand, the blank sawed into a circle and the bottom edge rounded. The result a cutting board with a flat close surface for slicing and a "well" in the back to accumulate the results.

While you are at it grade the free hand band sawing of the circle and free hand routing of the interior border.

Wow!

Barry Irby

That's some impressive work.

I have made about six of those cutting boards. I had forgotten I got the original idea from you. Thank you for the idea. I make the process much more complicated than you do. I glue up the blank end grain and rough it out on the bandsaw and then turn it on the lathe in a set of Cole Jaws with an offset piece under it. Mine are about 15 1/2" in diameter because my lathe has a 16 inch swing. They have been very well received as gifts.

I would like to know more about how you do yours. Impressive hand work. (Still does not look like any cherry I ever saw)

Cherry..

David Weaver

...coloration on a slab that's cut from a fallen tree will look like that.

I bought a huge 16/4 slab last year so that I could cut guitar necks out of it (plenty of thickness to saw in any orientation) and when I got it, I could tell that the pictures taken were favorable for the seller and either the log sat for a long time or it was cut from a downed tree.

There's a lot of brownish color like that in the wood, but it's otherwise fine for my purposes.

Never having been taught...

David Weaver

..by anyone, my gluing looks more like yours. It's never caused a serious delay in a project *except* when I glued my bench top together. I glued the piss out of the boards that I laminated for a simple reason - I got skip planed lumber and ran it through a thickness planer without ever jointing it - fast as I could get it together.

It's held up well, but I must've spent 20 minutes or a half hour dealing with the glue squeeze out.

Since I don't have a jointer, it would've taken *far* longer to joint the boards (and even if I had a power jointer, it would've used more of the board thickness).

Counter to that, my parents buy older furniture, but not 18th century old. More like 1800s to early 1900s. When the dovetails come loose, etc, there is almost no glue in them. I get the sense whoever was making the furniture got to using as little glue as they could get away with for speed.

I'm sure they lasted decades before the joints let go, and repairing them isn't much work, but some of the dovetail joints may have glue on 25% of the contact surfaces or less.

confusing production with hobby..

David Weaver

...there was a post more than a decade ago on SMC where someone made something nice, and the glue joint had squeeze out, and the usual suspects could only comment with things like "no respectable craftsman would ever do what you just did".

I'm guessing the notion of minimal glue comes from someone who has spent parts of their day loading 40 panels in a panel glue up machine and would notice more trouble keeping pace cleaning glue off (as in, they'll have a wet rag, perhaps, and the guy who works after them putting the panels through a wide belt sander will get pissed if there's big dots of glue)

How that's a big deal when someone can plane the glue off in a minute is beyond me. I spend more time with a vacuum cleaner in the shop than I ever have dealing with glue squeeze out.

Production gluing.

Bill Tindall, E.Tn.

We used to buy some of the lumber we resold from a nearby furniture factory. While Frankllin suggests a 0.008" thickness of glue (3 cents per square foot glue cost) what I saw in practice was hardly different from the excess I had on the panel. The camp racks got steam cleaned periodically to remove the stalactites. Sometimes I have been able to buy some sort of desirable rough wood panel over runs from a factory. It seems they generally want to see some squeeze out less than the cutting board and more than the demonstration piece.

If I have a steady diet of one thickness it gets easy to judge how much to lay down on the edge. The original point of the post was to show that glue spreaders and fingers are not necessary if one uses the "wipe" technique. Increase the edge width 3X and I guessed wrong, but wrong in a safe direction.

Strange cherry

Bill Tindall, E.Tn.

I never saw any cherry like what came from this tree either. Fresh cut it is hard to tell sapwood from heart it is so light. Nor is the considerable figure apparent. Let it sit out for a few months and it looks like this......

Sadly I sold a 20" wide x 2" thick plank to someone before I realized what I had. I'd buy it back for $10/ bdft but now it is a bar top.

Agree...

John in NM

From what I've seen, glue quantities used in actual production comes down to the preferences and priorities of the shop manager and/or business owner.

The shop I worked for did custom work for the most part, with the warranty generally expected of custom work so he told us all to not spare the glue. He figured a lifetime of wasted glue was still probably cheaper than just a few callbacks.

A real production shop that I almost went to work for was more the sort of place that I would imagine tries to use just enough glue and no more. They probably went through 10 gallons a week making the kind of stuff you find in public libraries and better hotels. As long as it lasted some period of time, say about 5 years(?), they didn't much care if it failed.

All that said, if a hobbyist takes good care with their jointmaking, I'm sure they have nothing to worry about using the thinnest application of glue they can manage. The joints I've seen fail were either poorly made or had suffered water damage.

Re: Production gluing.

David Weaver

agree with all of that and also don't spread glue out, but lay a bead and then allow the joint to spread it. It results in the same as you show, some squeeze out, but I don't walk around picking glue off of my fingers later (or faffing with cards or rollers).

There's a condition for my glue ups that maybe makes me care less about edge joints (and squeeze out), though - the boards are always still rough when glued (not the edge, of course, but just to clarify for folks on this side of the board, only the edge is cleaned up and matched).

Re: Too much glue - what I was taught

Johanna Johanson

Jesse, we are so fortunate to have such a great woodworking program available. I just completed an "Advanced Projects" class with Christoph Neander - he is still checking in with me to see how the dressers are coming along (not very fast - too cold!).

For those reading this who do not live in northern New Mexico - take a look at Christoph's web site: www.christophdesign.com