End grain cutting boards or chopping blocks are my favourite cutting surface and generally are the best for food hygiene and preserving sharp knife blades. However, because of the method of construction and specifically the varying direction of the grains they are susceptible to cracking if not conditioned and maintained correctly.
Recently a friend of mine sent me a picture of a beautiful maple and walnut butcher block island her husband had made. Unfortunately within a week of it being proudly displayed in her kitchen the end grain butcher block cracked.
Touch wood, I've yet to have a catastrophe like this on one of my boards which is why I go to great lengths to educate my customers on how to condition and maintain the boards I make. Phew! Let's hope that little superstitious rambling satisfied the wood fairy's.
So what exactly caused this board to crack? Well let's start with a basic understanding of wood and how it is structured.
Wood moves and continuously contracts and expands throughout the life of our project. It is naturally occurring due to how changes in moisture effect the the fiber cells structure and is exhibited to a lesser or greater degree by different species.
Even though the wood we use to build our projects is seasoned (dried so it has an average moisture content of between 6% - 11% depending on your location) it will continue to move.
Ever noticed your door sticking or a drawer on that old pine dresser harder to move in summer than in winter?
This is because the wood fibers expand as the moisture is absorbed in the summer, while they shrink when the water is released in the winter. This effect can be more noticeable due to the way we heat our homes in winter or by the amount of moisture we see in our summer months.
I remember when we first moved to Nova Scotia from Ontario. Whenever we had visited our holiday home during the winter I'd not noticed much difference in the movement of our wood doors or floors even though our heating was on while we visited for those short periods. However, I remember that first full winter after we moved, when I had the wood stove on night and day for months at a time. By the time spring came around I could see gaps under doors, gaps between floor boards and exposed unpainted wood on all of the floating paneled doors in the house. Yes, I sure dried our house out that first winter!
Okay, So Wood Moves. But Why the Crack?
Well, there can be a number of contributing factors as to why my friends butcher block or any end grain cutting board might crack. These include (along with brief explanations of why):
The surfaces to be bonded have not been correctly prepared.
- Wood glue relies on smooth, clean surfaces for achieving a good strong bond. Always use sharp saw blades and sand surfaces smooth before gluing.
The wrong or poor quality wood glue has been used.
- Not all glues are made equal. Use the best you can afford. I use Titebond 3. It is strong, FDA approved and is waterproof.
There were micro cracks already in the wood.
- Any micro cracks or stress fractures might weaken the board over time. Use the finest quality wood and discard poor pieces.
The board is too dry.
- Probably the worst condition for any wood cutting surface.
- Dry face grain and edge grain boards will tend to warp, end grain boards might also crack.
- Because we tend to alternate the grains to make nice patterns in end grain cutting boards this causes lots of stresses in many different directions if the board dries out.
The board is too moist resulting in failure of the glue bond line.
- As much as too little moisture causes problems so too does too much.
- Avoid submersing your cutting boards especially end grain boards.
- Never, never, never put your cutting boards in a dishwasher
The board has been hard mounted to another structure.
- Because wood moves it is important to understand how different grain directions affect stability
- Always use a floating mounting system when attaching a cutting board or butcher block to another substrate such as a frame.
Any one or more of the above conditions can lead to damage and ultimately the catastrophe of cracking or breaking your end grain board.
After some discussion and analyzing the photograph above I determined conditions #1, #2, #3 and #5 were not the issue. Her husband prepared the wood properly, used good wood glue and a careful study of the photograph shows the glue bond line did not fail as you can see the different wood still bonded together.
However, my friend did admit they had not done any preconditioning of the butcher block other than using some of my Board Butter she'd purchased at Christmas.
Now the board butter is a great wood conditioner but it is intended for use on face grain and edge grain wooden boards or as a final sealing on the end grain board after a proper conditioning oil has been applied. There's just not enough oil in the board butter to condition an end grain board. It will have the effect of stopping moisture from penetrating but the wood fibers which does not help if the fibers are already too dry.
For the majority of cases the reason end grain cutting surfaces crack is they are too dry. Often it is combined with cycles of wet and dry. Can anyone guess why you never, never, never put a cutting board in the dishwasher?
In my friends case it was that their butcher block was too dry and they had attached it to a structure below with screws. The effect of bringing the finished piece in to their kitchen meant there was an immediate change in the relative humidity which caused further drying, shrinking and finally cracking of their beautiful worktop. The screws they had attached it with did not allow any movement.
"The Professional" Fully Conditioned & Ready For Cutting
Stop The Cracking By Preconditioning
Here's a sure way to prevent your board from cracking and help in preventing excessive moisture getting in to the board. Before any of my end grain boards are shipped to a customer I always soak them using my Board Conditioning Oil this gives great long lasting protection and is the baseline protection required for maintaining your board for years to come.
When I say soak I mean just that. As an example everyone of my The Professional cutting boards receives about 250ml or more of my conditioning oil. The first time a board is conditioned is the most important. I soak the board on one side until the oil is pooled all over the whole surface. I also wipe it around every edge.
I then let the board stand for about 15 minutes. After this I can see that the oil has begun to penetrate through the cutting board. It will (and should) soak right through the board.
After 15 minutes you will probably see some areas that are drier than others. This means the oil has been totally absorbed by the board. Check the underside of the board to make sure the oil is penetrating through the board evenly and add more oil to the dry patches.
You can smooth the oil over the entire surface using your hand or a clean cotton cloth. I wait another 15 minutes and repeat the same process twice more. Then I leave the board for 24 hours. After 24 hours I take a clean cotton cloth and wipe any excess oil from both sides and all around the board edges. I then take another clean cloth and buff the board until I get the desired luster. Voila. A perfectly conditioned cutting board.
My Handy Maintenance Conditioning Oil
Your cutting board should be cleaned after every use. Here's my recommended cleaning procedure. Then I'd also recommend reapplying more conditioning oil at least once a month and certainly at no longer intervals than three months for a moderately used board.
If you want some added protection to prevent moisture getting in to the board you can add some of my Board Butter for good measure but it is not really necessary on end grain boards.