OH NO!!! Butcher block has developed a hump at the last minute!!!

[Tom Hammond]

I made a maple end-grain butcher block (24 x 30 x 2) a few weeks ago and it has been sitting un-oiled because of my work schedule. I've checked it every week or so, and it has been as flat as a smashed pancake. All of a sudden, in the last 48 hours... and, of course, just before I'm getting ready to oil it so I can give it to my wife for Christmas... it's developed a 3/32" hump.

I made the block by making 3/4" thick maple panels out of 1x2s, sanding smooth, cross-cutting into 2-inch strips, then gluing the strips together, alternating the matching joints. So, the pattern is a 'running bond.' The hump is consistent and goes all the way across the board, with the high point running parallel to the long joint line.

I had the board in my upstairs den for the past weeks and I am not sure how the humidity could have changed enough to cause this. I may have made one mistake in that I stored it flat, so one side was not exposed but the other side was. So, if it was a humidity issue... since I don't know now which side was up and which side was down... is the convex side or the concave side the one with the higher humidity? Since I discovered the hump, I've stored the board open on both sides, vertically, and the hump has subsided slightly to about 1/16"... but I can't tell you why. Very frustrating since it was dead flat for so long. ARGH!!

Any advice will be greatly appreciated. I've got to oil this thing by tomorrow to have it ready for Christmas!

[Matt Meiser]

The convex side would be the one with higher humidity. I had something similar happen with a non-endgrain top we had made for my parents' island but it flattened right out once I got it on stickers and put some weight (paver bricks I have wrapped in heavy plastic and duct tape.) Probably a few days to flatten.

1/16" I wouldn't even worry about at this point. You'll probably be the only one who notices. Depending on how you are mounting it you might want to fasten loosely then tighten it up later.

[Kent A Bathurst]

Turn it over. It will go back the other direction.

I have seen this before..all done, min oil, beeswax, on the counter...it moves. Turn it over, it goes back. Few weeks, its done moving.

[Tom Hammond]

I'm worried that if I oil it, it won't move any more. Do you think I'm safe going ahead?

Thanks for the advice.

[Steve Baumgartner]

If you oil it, you will slow down but not stop the movement. You could try warming the convex side with a hair dryer or the like (not hot enough to burn) and see if it will go down the rest of the way as it dries. That kind of movement is very typical with pine, less so with hardwood, but possible with any species.

[Tom Hammond]

Thanks guys. I guess I'm oiling her up this afternoon then.

[Michael Sobik]

I've been using my maple and walnut end grain board for more than four years now just about every day. It can sometimes develop a wicked arch...like 3/8". It just depends on how dry the air is, and how wet I get the board. Oil, wax, whatever else I put on it, none of that matters. Looking at the Boos blocks and boards, you will notice that they do not make an end grain board or block less than 4" thick. I believe the massive expansion that happens with end grain is why. While I like my board, the next one I make will be edge grain. Whatever you do, don't chase it trying to get it flat. Some days it'll be flat, others...not so much :)