soufiej wrote: ↑
Thu Jan 25, 2018 3:47 pm
"It's reaching an equilibrium. Adding moisture will increase the moisture content of everything in the case that can absorb moisture. Plastics and metals don't, under normal circumstances, absorb moisture from the air so you can ignore them."
The moisture content of everything in the case that can absorb moisture? That would include the case itself. I guess I just have no interest in a moist case.
Of course, plastics don't "absorb" moisture readily. But look at the mirror in your bathroom after you take a shower. It hasn't absorbed any moisture, but what has happened? That same thing that would happen with any nylon lining from a case if it were hanging in your bathroom.
Everyone gets to decide how best to treat their guitars. I just have a problem with the idea of putting my guitar in a case with a moist sponge or similar material and then closing the lid to restrict air flow.
No one's asked me but I keep my guitars on a multi-instrument stand and, if the interior air gets so dry I think I need to add a soundhole humidifer, I simply toss a cotton cloth over the guitars. At present, my Larrivee parlor, with a soundhole humidifer, is staying in a cotton pillow case on its stand by the sofa. I play that guitar almost every day and it takes just a few seconds to remove the covering.
If the case is made of wood, it will too absorb some of the moisture. It will be exactly like the guitar.
The reason the mirror gets condensation on it is because it is cooler than the air. The hot water from the shower heats the air as well as adding moisture. Because the mirror is cold it cools the air close to it and the water vapour in the air condenses into droplets. This also happens on the walls, but you don't necessarily see it because they are generally made of plaster which absorbs the water. Unless you cool the outside of your guitar case or put hot water in it, that will not happen with the guitar case.
Your method is fine, except that you need to add water to the humidifier much more frequently as it is losing humidity to the air in the room and will not reach equilibrium unless you seal the room and keep adding water until the entire room is humidified. The cotton bag will not act as a barrier to the water vapour leaving your guitar, but it will slow the process by reducing draughts blowing over the humidifier. So if it is particularly dry, your method is simply not going to be as effective as closing it in the case with the humidifier.