End Grain, Edge Grain, Face Grain
When embarking on wood projects, it is important to understand the differences in woodcuts. As a woodworker, any piece of lumber has three surfaces referred to as end grain, edge grain and face grain, which can give the wood distinct moisture content (MC) characteristics. Wood enthusiasts, pros and hobbyists alike, must effectively manage the MC profile of all wood grains.
End grain is the grain of wood seen when it is cut across the growth rings. Rather than cutting a plank of wood the length of the trunk, end grain wood is actually cut at a 90 degree angle to the grain. This type of cut exposes the character of the wood rings and graining. Many wood lovers relish the results: a cross-grain which pleases the eyes and the wallets. Put simply, end grain cuts produce highly-aesthetic wood with character, color and durability.
End grain boards are typically used to manufacture butcher blocks, as an example. The end grain boards are made by cutting the pieces of lumber into blocks and gluing the blocks together with the end grain up, forming the top surface of the cutting board. This block construction makes the butcher block very strong and durable. During cutting and chopping, the end grain wood fibers absorb the impact of the knife blade so the block is resistant to nicks and gouges. One needs only reflect on the culinary punishment unleashed on chopping blocks over time to grasp the durability factor of end grain.
In fact, end grain flooring tiles are a very unique form of flooring that has been used for one particular goal: durability. End grain floors were traditional floor coverings in factory buildings, heavy traffic commercial buildings and boardwalks, to name a few applications. They absorb energy and noise, and the angle of cut allows for the growth rings to resist scraping and general wear.
Since wood cells hold MC in their nuclei and cell walls, end grain cuts naturally react differently to moisture interactions between the wood and the ambient relative humidity (RH) of the surrounding air. Lumber can be a very absorbent material, particularly through the end grain. In fact, end grain wood absorbs moisture content at up to 100 times the rate of absorption of the face of a wood piece. If you consider that most wood cells have a roughly straw-shaped structure, you can see that the moisture can travel more quickly into the wood from an end-grain cut. Many wood professionals recommend sealing end grain wood to slow down the absorption even before beginning a project. When storing wood for extended periods of time or in non-climate controlled areas, sealing this end grain is also highly recommended.
End grain MC absorption is one of several conclusive reasons to purchase moisture meters for wood. Moisture meter products commonly measure the MC levels in the wood up to a ¾” depth penetration below the wood surface. In fact, moisture meters for wood, like the Wagner Meters MMC220 “Extended Range” model, are programmable for hardwood, softwood and exotic wood species applications. Thus, wood builders and hobbyists can monitor those end grain moisture fluctuations with moisture meters for wood.
Edge Grain & Face Grain
There are two alternatives to end grain when manufacturing butcher blocks as a woodworking project (as an example).
Edge grain (or vertical grain) is produced by quarter-sawing the lumber so that the edges of the growth rings are exposed on the widest faces of the piece, and the rings form angles of 45 to 90 degrees with the widest faces.
Face grain is when a board has one side that is wider than the other; the wider side is referred to as the face, as opposed to the edge. This also may be referred to as the face that is to be visible in the finished product.
Edge grain boards for butcher blocks are usually made of strips of wood, and after the piece of lumber has been cut into strips, there is a choice of which grain to put facing upwards. When the edge grain is up it is an edge grain cutting board, and when the face grain is up it is a face grain cutting board. The key difference from end grains is that these cuts are a little more resistant to stains and absorbing moisture.
Don't be confused if woodworkers use the term flat grain. They are simply using an umbrella term that refers to wood grain from either the edge or the face. As an example, in most maple wood cutting boards, the strips of wood can be glued together randomly, resulting in a mixture of both grains (a.k.a. mixed grain). This distinction is largely one of appearance, but when it comes to building with or maintaining mixed grain wood projects, special attention should be paid to the ongoing MC levels.
Wood Moisture Meter
Woodworkers, hobbyists, builders and consumers must care about the differences in grains due to their MC characteristics. Lumber mills deploy multiple forms of industrial wood moisture meters in order to prepare "green" timber for the kiln drying process. Equilibrium moisture content (EMC) is achieved when the MC in the wood is balanced with the ambient relative humidity (RH) of its environment. However, a wood’s MC continues to fluctuate naturally with changes in RH. Thus, moisture meters for wood represent a sound investment in overall MC management.
A wood moisture meter is especially apt for managing the MC differences in wood pieces during the gluing process. Excess MC can cause adhesives to break down between glued edge grain and face grain wood strips, as well as between end-grain pieces. There are multiple challenges that can result from the wood’s moisture, and the differences in the MC between wood pieces can magnify how they manifest themselves too. Excessive MC in the wood can also interact with the adhesive itself to erode the bond.
Moisture meters for wood are useful in the finishing process as well, as many manufacturers are removing volatile organic compounds (VOCs) in favor of water-based finishes. While edge grain is a little more resistant to staining and absorbing moisture, using specific moisture meters for wood lead to informed decisions regarding when to apply the next coat of finish. When end grain is saturated, a wood moisture meter informs assessors of the need for dry-out time (or a sealer).
A wood moisture meter assures that a wood product’s beauty and performance are ingrained with wood diversity.