Need a Hand: Cutting Board Failure

[Brody Goodwine]

Finally had the guts to split it. You guys tell me, but it does look a bit dry. The portion that split first (right in the pic above) is at the bottom here.

[Jeff Duncan]

Yup, finishes take much longer to fully cure than to dry to the touch. Oil based Poly for instance dries to the touch on the surface of the coating while the finish below dries much slower. Water based finishes dry a little differently, but remember they also allow much easier moisture exchange than oil or solvent based, even when fully cured! For water based finishes take a look over at the Target finishing site. They have a lot of great information much of which will translate to other water based finishes.

There is a lot of information that can get confusing regarding dry/cure times. Many books, (including Flexner's) say to wait several weeks or a month before rubbing out a finish. The reason I use rubbing out as an example is b/c the finish needs to be fully cured for it to be done properly. So while you may see different information regarding different drying and curing times, this seems to be a pretty standard timeline for full cure. I'd go back through your Flexner book to see, he's forgotten much more about finishing than I'll ever know

One thing is pretty much a safe bet, any finish you buy off the shelf will need more than 48 hours before exposing to moisture

When you split the block did it split the actual glue line? Or did it split the wood along the glue line? If it split the glue line itself, bad glue! If it split the wood along the glue line then it was the wood movement causing the problem.

JeffD

[Jeff Duncan]

As far as the grain orientation goes, I'd still be worried. Here's the thing though, you already have the block mostly made. I would clean up the edges along the split and glue back together with a fresh batch of glue. Then ideally I'd leave it in the house for a week or so to acclimate to a similar moisture level to what it will be used in. After which hopefully someone will volunteer their wide belt or drum sander for you to use as it will allow you to sand right through those stains quickly and get the block nice and flat again.

If you choose to finish with water based again be sure to finish in as ideal conditions as possible, i.e. keep it warm! 65 degrees is OK, but it won't hurt to brink the heat up a little either. Then let it cure for a good month before exposing to warm water. With an oil based poly or solvent finish it will resist water much quicker. And just to emphasize, you don't want that block to stay wet for any length of time with a water based finish on it. If you need to clean it do so then dry right away. FWIW I used one of the toughest water based finishes available to spray my mahogany c-top at home....with a farmers sink So I have a little experience with water based and how they hold up, and what they're vulnerabilities are

good luck,
JeffD

[Brody Goodwine]

Jeff, it split the glue line over the maple and then split the walnut, not the glue line at the end. I had Flexner's book out at the gym today. I'll be 100% certain before any more finish work.

[Jeff Mohr]

An interesting thing about the finish suggestions is the lack of true evidence. As a scientist by trade, I find it very interesting there have been no specific studies on the effect of chips from curing finishes or any of that type of finish but there are several recommendations that it is "safe" to ingest. To be fair, I am sure there are not many specific tests on mineral oil either. What I do know, however, is one type of finish (mineral oil) is sold as a laxative that one ingests while the other is not sold as an ingestible substance and in its current state is deemed harmful and only after it "cures" is it supposedly "okay" to eat.

I think the clear winner for my boards is the mineral oil.

[Myk Rian]

Don't worry, Mom still loves you.

[Greg Peterson]

Brody - beautiful cutting board.

I would consider the failure of this board catastrophic if indeed all it saw was a damp wipe down. Obviously the poly was inadequate and I'm not sure more of the same is going to produce the desired result.

Sometimes a client (including mothers) want something that simply is not in their best interest or possible for that matter.

Mineral oil and bees wax is the standard finish on end grain because it works. You might consider woods that share similar expansion/contraction properties.

The first picture looks like there are gaps in some of the maple joints. This indicates the wood was not milled to close enough tolerances. I would not try to salvage this board as the wood has absorb some of the poly and it appears the pieces are not milled accurately enough.

End grain cutting boards are a tough project because they require a high degree of accuracy. The slightest offset in size or square quickly gets magnified, not to mention weakens the integrity of the unit.

Consider the lessons learned and start a new one from scratch paying particular attention to milling, glue and finish.

[Dennis Lopeman]

Thanks everyone. I too have learned a lot here. I used TiteBond 3... and it's old. It's still very strong and I have done test after test with it on my cabinet raised panels. I break the cut-offs and try to break at the glue line (usually as a demonstration to friends) and it almost never broke the glue - it broke the wood (cherry in this case). I am currently building a butcher block and will post in a separate thread (so as not to hijack this one!!) to get some valuable opinions.

But thanks again for helping this guy out. I will be applying some new knowledge to my current build.

[Jeff Duncan]

MY personal opinion is that glue is cheap....if your titebond is more than a year old you can pick up a fresh bottle of TB1 for about $5.....a little more for the other flavors. Why risk failure for what's essentially 2 cups of coffee at the donut shop? Also I wouldn't go soley by your breaking the off-cut test. Sure the glue may be fine, or maybe not. Maybe it's holding well now but doesn't hold up over time? I just see no reason to risk a project which will likely cost a lot more than $5 to replace

good luck,
JeffD

[Dennis Lopeman]

Understood. I bought this GALLON ($32 or lots of coffee) when I didn't realize glue had an expiration date. I will now buy it in smaller quantities. If I learn later that my glue joints are failing, I will also try using TB 1 or 2 or some elmers white... It seems the school of woodworking can carry on indefinitely!! I have no problems with that.

Unfortunately for me... I'm a little "after-the-fact" here (as is our thread owner here!) and will just have to watch and learn and chalk it up to the school of hard knocks!!! Fingers crossed that I don't get caught cutting class...... Tuition and Supplies sure can be expensive!!!