Now while we covered Truss rod maintenance last week, this week I am going to cover something that pertains more to the average joe who plays out regularly, or who is ordering guitars over the internet this time of year, the finish on your guitar. The finish on your guitar is a lot like the finish on a car, it is there not only to look nice, but it is also there to keep the elements from destroying it. The finish on a guitar keeps the wood from absorbing too much moisture, or being too easily damaged by things like your pick hitting it, or your arm resting against it. The reason I bring this up is because of what cold can do to the finish of a guitar. On most modern consumer priced electrics, your finish is poly urethane, which is hard and flexible. So cold, hot, wet, dry, it won’t shrink or warp. Older guitars, and some high end modern guitars are finished in Nitro Cellulose, which is a much thinner and far less flexible than modern finishes, and can crack, crumble, and “check” when you take them from a cold environment to a hot environment too quickly, like say from a cold car to a warm living room. I’ve even heard stories from some of our reps about expensive guitars cracking like ice on a lake from them opening a guitar infront of a fire place after a long January car ride.
The adverse effect of this is that once the cracks form, the body of the guitar can change temperature, humidity and size and shape much quicker, and thus the cracks will multiply much faster once they start forming. Now on an electric, this isn’t that big of a deal, it can look pretty cool, and some guys like Rory Gallagher, Andy Summers, and John Mayer, actually prefer the feeling of a guitar whose finish is falling off of it, and some people like Nuno Bettencourt, actually like it best when there is no finish on the guitar at all, and their guitars are structurally just fine. The real problems start to show up when something acoustics finish starts to come off, as its finish serves a double purpose of also helping the guitar retain moisture. Because the underside of the wood is left bare, and the top is finished (typically with a heavy coat of poly urethane on a modern guitar) the moisture can only leave the thin sheet of wood from one side, meaning it takes longer for the wood to shift, allowing the moisture to leave at a slower rate. If you’ve ever had a guitar that got too cold, you might notice a significant amount of dehydration, this can cause weakness in the wood, and can cause a type of waviness to appear in the finish, which while rarer in poly-urethane finished guitars, does occur. This can usually be fixed by re-hydrating the guitar, but on some older guitars it does appear to be permanent.
Now, the danger of a dehydrated guitar is usually pretty minor, maybe a rather flat sounding set, or you might have some trouble with the action on your higher frets, but most of the time it’s very minor. But if you leave it unchecked, the wood can start to get very brittle, and can more easily be damaged by say, your picking hand, and sometimes, if it gets cold enough, the wood itself can begin to shrink, and if the wood is dry and brittle, you can start to see splitting in the wood itself. Sometimes they are tiny and easily fixed, and well sometimes, they aren’t.
So how do we prevent this? Well first off, always keep your guitar hydrated, and as often as you can keep it warm, not hot, but warm. Only about as warm as you would want to be, if you would be too cold in a room, or too hot, the guitar likely would be too. The next is don’t be too sudden when opening a guitar case when moving it from in doors to outdoors, or outdoors to indoors, the temperature change can cause the rippling we talked about or on a thinner finished guitar, can cause checking and cracking as well. A good rule of thumb is wait 12-24 hours after you arrive before you open it to be safe. Lastly, keep the strings slacked if it is going to have to endure the elements for too long, because the added tension on the top can often cause problems, yet again this is normally only on acoustic guitars, but it’s good practice regardless. Proper guitar care is easy, not something to be feared or fretted about, and when done regularly, you can greatly extend the life of the instrument, and keep it in mint condition for years to come.