Wood is a truly amazing material. It has been used for thousands of years in a wide variety of applications and is revered for its natural beauty.
There are many species of wood that all have different characteristics, but they are all composed of microscopic cells enveloped by wood fibres. This lattice, even when dead, can still act alive. Pores absorb moisture, fibres move, and the entire wood structure can flex. Many woodworkers fail to consider this and end up with flaws in their creations. A great book to understand the properties of wood and improve your woodworking is: A Craftsman's Guide to Wood Technology.
Raising the grain is one technique to counter flaws that can happen from failing to understand the structure of wood. When sanding a piece of wood, it seems like you are removing an even amount of material from across the surface of the wood, but in reality you are also 'pushing' down the grain. When exposed to water, these 'pushed down' grains can rise back up, resulting in an imperfect surface. A common way to tell if a cutting board, for example, didn't have the grain raised properly when it was made is if the wood appears 'fuzzy' when you expose it to water.
This effect can be seen in the image below. This piece of pine was sanded to 120 grit and exposed to water, leaving a fuzzy texture.
You might ask: How do I know when to raise the grain woodworking? It is really quite simple. Raising the grain is only required for water-based finishes.
With oil based finishes it is not necessary. Some schools of thought say you need to use a rapidly-evaporating alcohol to raise the grain to avoid permeation of liquid into the wood, but for all applications I have used this is negligible. All I do is use a spray bottle filled with water and lightly spray all surfaces of the piece after sanding it to 180 grit. After letting it dry out in an open space for ~10 minutes, I take some 220 grit to the piece and then finish it with my water-based finish.
When I’m using water-based finishes, my go to is Howard’s butcher block conditioner. It is food-safe and gives a beautiful finish. Please note that raising the grain is a fine woodworking technique that is only used in situations where the wood is not regularly exposed to moisture. For outdoor applications you will need to use a waterproof finish.
The process of raising the grain is shown in my video where I use a water-based finish on some wall art. Check it out here - Wood and Epoxy Project | Mountain Lake Wall Art
Raising the grain is also a critical process in making end grain cutting boards. Read my article on end grain cutting boards here: The End Grain Cutting Board: Everything you need to know
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