We live in a very dry area in the US. One of our main concerns here is to provide our customers with real world knowledge about humidification and letting their instruments cure. Did you know that properly cured guitars need very little humidification? We’ve had nearly 100 year old Martin’s here for repairs that have no cracks or fretboard shrinkage – and won’t ever. These old Martin guitars were dried or cured properly prior to building and are nearly impervious to humidity changes. Sadly, guitar manufacturers are making instruments faster and striving to reduce costs – which means less drying time or attention to proper lumber selection. The best thing to do in this environment is to help your instrument cure and acclimate to the environment gradually over time. Once your instrument is properly cured – it will not shrink or crack. Unless of course the top was installed when it was still damp – that top will eventually crack and there isn’t much you can do about it.
Too much humidity can cause checking of your finish, warping, collapsing of the top, loose bracing, neck warpage, softening of glue joints, separating bridges and more. Extreme dryness can cause many of the same issues but especially fretboard shrinkage (sharp fret ends), cracks, bridge/top separation and more. We recommend just enough humidity usually 30-40% max in your case or sound hole – enough to keep the guitar from cracking (which happens when a guitar acclimates too quickly) – the best amount to allow the instrument to acclimate over time to the environment. Over humidifying your instrument is just delaying the inevitable – the wood shrinking/drying/curing. If this process is allowed to occur gradually it will not harm your instrument and eventually the instrument will need only minimal hydration.
Be warry of repair shops claiming to have high humidification (70% or more). That much humidity can potentially cause the issues listed above that are characteristic of the premature deterioration of your instrument – especially here in the desert.
N. Smith