Why finish wood?

The main reason that we finish wood is for beauty!

Adding a finish to a piece of wood will dramatically improve how it looks.  Almost all finishes will make the grain more visible, and most finishes will also make the variety of colors more visible, too.  If you’ve ever added a finish to a raw piece of wood then you have experienced the wonder of wood finishing.  For woodworkers, adding that first coat of finish is nothing short of magical!

A typical woodworking project of mine will take weeks, and often months to complete.  When I am finally ready to present my work to the world, I want it to look absolutely as great and gorgeous as it can possibly be.  For me, and for most woodworkers, there is no question that the main reason we finish wood is to beautify it!

Finishing wood can help to stabilize the moisture content of that wood.

Wood is a hydroscopic material, meaning that is will absorb and release moisture.  Typically, wood will absorb moisture from the atmosphere when the humidity is high, and it will release moisture when the humidity is dry.  This seasonal variation will cause the wood to expand and contract. Different woods will “move” more than others, but all woods have some moisture content.  Adding a finish will not prevent wood from expanding and contracting with seasonal variations in moisture content.

An extreme example of the way that the moisture content of wood can change is if/when it has direct contact with water.  To put it more plainly, imagine if you poured water directly onto a piece of raw, unfinished wood.  Most woods would rapidly absorb that water, and most likely they would warp from that excess amount of moisture.  Now imagine that same board had a few coats of shellac or polyurethane on it.  In that case, most of the water would just run off of the board and very little of it would be absorbed into the wood.  This is what I mean when I say that a finish can  help to equalize the moisture content of wood.  Not that the finish will prevent moisture from getting in the wood, but that the finish can help to moderate the swings in moisture content.

Another reason we finish wood is to protect it from dirt and stains.

Raw, unfinished wood will quickly discolor through normal use from exposure to dirt, liquids, and oils.  Adding a finish can dramatically affect whether and how much discoloration will occur.

But, wood doesn’t have to be finished at all.

In fact, sometimes you are better off NOT finishing wood.  The best example of this that I can think of is outdoor furniture.  I say this because even the very best wood finish will eventually succumb to the elements.  Water, excessive temperature swings, and especially UV rays from the sun are relentless.  I stand by what I said in the previous paragraphs.  A finish can definitely add beauty, protect from discoloration, and help to stabilize moisture content and there is nothing wrong with finishing outdoor furniture.  Just know that finish will require regular maintenance.  Every so often you will have to renew, or maybe even completely refinish your outdoor wooden furniture.  I can certainly understand why the added beauty might be worth it to you.

Rather than add a finish, maybe build your outdoor furniture from a more weather resistant wood. Wood will turn grey if left outdoors, but White oak and several other species are very weather resistant.  Furniture build from one of these woods can last outdoors for years with no finish at all.  Finishing or not finishing outdoor furniture is simply a choice, and neither is necessarily better than the other.