Glueup issues with cutting board

[Michael Mayo]

Alright so the wifey wanted a cutting board she could take with her when she chefs at the catering events she does. She said she wanted something lighter than the big ones I made her for the kitchen. I said no problem and went about making her the cutting board. I decided to use some Maple and Mahoghany that I got recently. I cut strips 1" x 3/4" and was planning on 16" x 12" approximately sized board using the 1" dimension as the thickness of the board. So I got all the pieces cut and glued them up. When I went to plane it perfectly flat the board snapped in two right at one of the maple/mahoghany joins? So I re-glued it up and several hours later I took it out of the clamps and went to lat it down and a different joint split in two? I have made a couple of cutting boards in the past and never had any trouble withe Tightbond 3 not holding like a gorilla to a banana. Is mahoghany inherently resistant to being glued to another different piece of wood? My plan was for a checkerboard design cutting board but at this point I am thinking about ditching the mahoghany and using something else or is it me doing something insanely stupid and not realizing it ? Which is always a high probability.

[Rick Fisher]

Hmm..

Inadequate pressure when clamped ?
Sprung joint ( too much ) .. ?
Old glue ?

[jim gossage]

Probably old glue, inadequate glue time, or something is contaminating the surface of the wood and preventing proper glue adhesion (e.g. sawdust, silicone, oil, etc). I am assuming that the strips are all parallel and that the joints close easily with only minimal clamping pressure. If the joints are well machined, it should only require light clamping pressure to close them. If it requires high pressure to close the joint, it may pop open later (though usually not that quickly in my experience).

[Peter Quinn]

Check the MC? I had an issue some years back where I glued up the same three mahogany boards into a table top, the glue joints failed three times in a row. Maddening. I chased every angle....use more clamps, use less clamps, new glue, rejoint, longer clamp time. Nothing made a difference. I checked the MC, just below 6%, too dry, it was sucking the glue joint dry, starving the joint. Mahogany is not generally a difficult species to glue up, in fact quite the opposite. My solution was add moisture by wiping the edges with a damp towel just before glue up, then sizing the edges with tite bond III thinned about 40% with water, let that tack up for a few minutes, then glue up with full strength titebond III as normal. The top remains well glued to this day.

My line of thinking is that mahogany is quite soft and fairly porous, maple is fairly hard and less porous. Perhaps the mahogany is taking most of the moisture from the glue line, leaving the maple side starved? I've glued plenty of maple to maple and mahogany to itself without issue, I'm thinking it may be the combination of the two thats causing your problem. Glue up two pieces of maple, they absorb the glue and moisture at a fairly similar rate, good glue joint. Perhaps if you were to size the mahogany side of each joint it might solve the problem? That approach might not be viable when you get to the checker board part of the construction. Not sure if this is on target as a solution, but its worth considering if all the more obvious potential problems don't yield a solution. PVA us generally so easy to use it feels fool proof, but once in a while its water based chemistry presents a challenge.

[Darius Ferlas]

My line of thinking is that mahogany is quite soft and fairly porous, maple is fairly hard and less porous. Perhaps the mahogany is taking most of the moisture from the glue line, leaving the maple side starved? I've glued plenty of maple to maple and mahogany to itself without issue, I'm thinking it may be the combination of the two thats causing your problem.

That's exactly what's happening.
Sometimes saturating the more porous wood with glue, waiting a few minutes and then applying fresh glue to the less porous wood works. For a cutting board, consisting of multiple elements, this may be a relatively lengthy process. As Rick suggests, clamping pressure is important too. There was an article in FWW years ago where they suggested rather high numbers for the required clamping pressure. The numbers escape memory right now, but if using parallel clamps you'd need to squeeze them with pretty much with all you've got.

I used use this successfully bonding hard maple to walnut.

[Michael Mayo]

That's exactly what's happening.
Sometimes saturating the more porous wood with glue, waiting a few minutes and then applying fresh glue to the less porous wood works. For a cutting board, consisting of multiple elements, this may be a relatively lengthy process. As Rick suggests, clamping pressure is important too. There was an article in FWW years ago where they suggested rather high numbers for the required clamping pressure. The numbers escape memory right now, but if using parallel clamps you'd need to squeeze them with pretty much with all you've got.

I used use this successfully bonding hard maple to walnut.

I had pretty strong clamping pressure using aluminum bar clamps and they were as tight as i could make them. I think both you and Peter are correct. I will try using the pre-gluing technique today. The wood has been sitting in the guy's basement for who knows how long and as such I would guess the MC is quite low especially with the mahoghany which seemed to be very very dry. The machining I did was spot on and all pieces were very square and parallel so i don't think that was the issue. Back to the shop for another go. Thanks for your insights they are very much appreciated.

[Peter Quinn]

I had pretty strong clamping pressure using aluminum bar clamps and they were as tight as i could make them. I think both you and Peter are correct. I will try using the pre-gluing technique today. The wood has been sitting in the guy's basement for who knows how long and as such I would guess the MC is quite low especially with the mahoghany which seemed to be very very dry. The machining I did was spot on and all pieces were very square and parallel so i don't think that was the issue. Back to the shop for another go. Thanks for your insights they are very much appreciated.

Clamping pressure is never my first guess, I'd guess you were fine, I've seen rub joints you couldn't break without a hammer, I think that whole FWW article was a bit dubious at best. Seen your mortise and tenons falling apart lately? Not much clamping pressure there inside the joint. I'd also guess your machining was fine, and at that thickness, even if there were deviations, its of little consequence. I've taken piles of not so flat scraps out of the bin at work, sent them through the planer, and glued them up with good results. A pile of clamps will make thin material conform. I've seen a few odd cases with PVA glue where the moisture either left too fast or could't leave and it failed. I seem to remember a good FWW article explaining the exact chemistry involved, but basically water is a catalyst and a sort of retarder in these glues (like titebond). If it leaves too fast, the bonding reaction hasn't had time to happen, the joint is weak. This may be your case. I've also seen this with torrified (toasted) wood that has become more popular of late. The stuff is so dry it can be difficult to glue. Until the moisture leaves, the bonding reaction can't happen. I've seen this in very hard non porous exotics like Ipe and cumaru. The stuff is so hard and non absorbent the moisture can't evacuate into the wood, it has to leave at the glue joint surface. I've left it in clamps for 5 hours, pulled clamps and had it fall apart, the glue line was still wet. let it go overnight, joint strength is high and never fails, same wood, same glue, same clamps, same temperatures involved. Go figure. Glue two pieces of white oak together, I've gone through the planer 1 hour later without failure, though I usually give it more time than that, its been done. Tricky business this glue.

[Mel Fulks]

You didn't say how many pieces you were gluing at one time,the stuff can set fast in a warm room .I favor glue on both surfaces for edge gluing .Sometimes the pieces slide around too much when there are a bunch of them ,I like to put spring clamps on the ends to keep all aligned.

[Michael Mayo]

You didn't say how many pieces you were gluing at one time,the stuff can set fast in a warm room .I favor glue on both surfaces for edge gluing .Sometimes the pieces slide around too much when there are a bunch of them ,I like to put spring clamps on the ends to keep all aligned.

Mel,
I did just as you stated and still had the failures. I cut some new pieces and re-glued everything after moistening the edges of the the strips and it is still in the clamps as it was raining today. Will have to see how it made out tomorrow.

[Mel Fulks]

Bad or old glue was suggested earlier ,maybe that's it.If you have another type of wood glue you might try it on a couple of sample blocks before trying another whole glue up. Have no idea what else could be happening . Sorry.