wood drying - part two
What is Wood Moisture Content. How does it concern our guitars?
In part one, we have discussed Wood Moisture Content (WMC) and Equilibrated Moisture Content (EMC) within acoustic guitars. In this part, lets' talk about the available products that are created for guitar dehumidification and the effects of it.
Here is a short read on humidity to start you off: http://www.physicalgeography.net/fundamentals/8c.html
I hope you can remember free water and bound water within wood. They are the mechanisms that underpin moisture retention within wood. However only bound water is responsible for dimensional changes in wood, as well as in guitars. If guitar is too dry, shrinkage will occur. That may result in cracking and warping. When it is too wet, glue joints may loosen and guitar top many bulge. All are no good for guitars yet these physical changes are inevitable.
Keeping your guitars healthy
Among many guitar maintenance issues, keeping guitars at their optimal moisture content has proven to be challenging. Setting up a 24/7 climate controlled room will do the job but this option is accessible to limited individuals. As such, product developers have churned out various products to fit consumers of various segments as well. The more products available, the more questions. It does beg the question of which product is most effective or otherwise.
Invariably, many humidity control products in the market are not entirely transparent in terms of their effectiveness. E.g. when you place a pack of desiccant materials into guitar case with a guitar in it, how can you determine its effectiveness? While the act of maintenance is easy to execute but evaluating the outcome can be ambiguous.
In North America and Europe, dry guitars related issues are common whereas within the equatorial regions, "WET" guitars are most prevalent. Since Guitaring Passionately originates in Singapore, I shall focus on "WET" guitars.
Humidity control products
Lets’ begin with desiccant typed humidity control products. Such products promised to dehumidify guitars a.k.a. to dry or to absorb moisture from. To name a few; Zorb-It, Charcoal Dehumidifiers, Thirsty Hippo, Silica Gel, etc. Such products usually are stored with the guitars to be dehumidified in a closed containment for a predetermined period. There is little doubt that these desiccant products will absorb moisture but from where?
From part one, we have learned that free water within wood can be evaporated naturally. However purging bound water needs energy supply. Physical changes in wood are governed by bound water as well.
These desiccant products are placed into guitars. They are in fact absorbing the moisture from the ambient air within the closed containment thus reduction in humidity to the ambient air within is attainable. However to claim that desiccant products will also absorb free water from wood (guitar) is speculative. Much less for bound water. It is Physics 101; to break any chemical chain or bond, energy is required as heat. These desiccant products don't generate heat therefore purging bound water will not be possible.
Are desiccant products still useful?
Does it mean that such products are irrelevant to guitars? Not really; because such products are likely more effective in maintaining the humidity level of ambient air. In this case, it is the air within guitars' soundboxes. That means guitar stored with such desiccant products should maintain healthy levels of WMC for longer period as compared to guitars leave in the open. In theory that is.
To determine effectiveness of dehumidification
"WET" acoustic guitars experience top bulge. That also increases string height at 12th fret (see picture). If you wish to determine the effectiveness of dehumidification, allow you guitar to take in moisture naturally for couple of days. Measure the string height at 12th fret.
Next activate the desiccant product you have to treat the guitar according to its instructions. At the end of the treatment, measure the string height at 12th fret once more. If it works, you should expect reduction but if it doesn’t, quickly contact a friend who owns a dehumidifier and restore your guitar.
Personally I have tried it and I have observed very varied results. Disclaimer; it is entirely your free will to try it and I shall not be liable for any mishaps or damage to your guitars.
Next part, I will discuss other dehumidifying methods and their effectiveness.
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