The value of an in-case humidifier

In August 2017 I wrote an article titled ‘Humidity and your classical guitar’, and ever since then, I have been recording local humidity levels. In a previous article, I explained the system and mix I use for in-case humidity control. In this article, I want to give some feedback on the readings I have taken.

I did not record humidity levels every day, but only when there was a meaningful movement from the norm. I live in the Johannesburg area of South Africa and the general average humidity here is 60%. The average highs are 70% for 3 months of the year, and the average lows are 45% for another 3 months. However, from time to time the conditions change dramatically to averages of more than 70% or less than 25% for a week or so at a time.

During the last 2 years, I have recorded 241 humidity readings and these reveal the following:

61 readings were 65% or more of which the highest was 81%. 48 readings were 25% or less and the lowest of these was 10%. However, and this is an important ‘however’, the highest in-case reading was 62% and the lowest was 41%. So, although the average in-case humidity of my guitars was 51% compared to an external average of 47%, my instruments were protected from protracted levels of over 65% or under 25%. When the external humidity was 81%, the in-case humidity was 62%, a 19% difference. When the external level was 10%, the in-case level was 41%, a massive 31% difference.

Another major benefit of in-case humidity control has been that the levels the guitars have to deal with change very slowly compared to sudden and drastic external changes. A sudden drop to 10% can cause a hand-made guitar to crack and a sustained level of 80% plus can loosen the seams and frets, change the fret-board inclination, and make the instrument sound soggy and buzzy.

So, there you have it. Even in a moderate climate such as Johannesburg, in-case humidification is definitely needed.

Knowing your classical guitar

 

My apologies to experienced players, but I wrote this article for those just starting out as players or interested non-players.

In this article, I deal briefly with a range of aspects of guitar construction, playability, intonation, humidity, strings and so on. I have only built one classical guitar, but I am a passionate enthusiast and I have researched and experimented quite a bit.

HERE is the article.

Humidity and your classical guitar

Too little moisture in the air for too long and your guitar could crack; too much moisture and it can swell and become hard to play. The measure of the moisture in the air relative to temperature is called Relative Humidity (RH) and this is expressed as a percentage of the airs ability to hold water.

The best way to control your guitars environment is to purchase a hygrometer that has an external gauge and display plus a wireless secondary instrument that you can insert into your guitar case. I have been using one by Acurite for over a year now and I have found it reliable enough for the purpose provided you calibrate it and make the adjustments accordingly. There are few places in South Africa where the RH is extremely low or excessively high for long periods of time but anything above 70% or below 30% for more than a few days is problematic. However, if the change is slow then the guitar would probably handle these extremes reasonably well.

The simplest and cheapest way of controlling the RH is to keep your guitar in its case whenever you are not actually playing it. In addition to this, make a simply humidifier and place it in the guitar case just under the headstock right up against the small accessories compartment. Here is how you make the humidifier:

  1. Take an empty plastic butter/Buttro container about 150mm x 100 x 50 and drill or cut a number of holes in its lid.
  2. Cut a piece of sponge to size (the type you use for washing your car is ideal) and place it inside the container, ensuring that there is a gap of about 10mm between the sponge and the lid.
  3. Dampen the sponge well but not excessively with one part water and four parts propylene glycol. However, when you top up you usually need to only add water as the propylene glycol will remain in the sponge for quite some time. I have found that in typical South African conditions 80/20 propylene glycol to water works fine (4 parts PG: 1 part H2O) and keeps the RH at about 50%.

As the RH drops, the sponge will release moisture into the air within the guitar case. However, what is not often mentioned, is that it will also remove excess moisture when the RH is high. By mixing propylene glycol to the water you can control the maximum amount of moisture the humidifier will release. You will have to experiment a little with just how much propylene glycol to use to get the stability point in your particular environment at around 45% to 50 % RH. If you live in South Africa you can order the propylene glycol from http://e-liquid-concentrates.co.za/  Propylene glycol is both an antibacterial and antifungal agent preventing mould from growing in the container.

With this simple humidifier, you should be able to keep your guitar all year round at a moderate  RH level and avoid any of the nasty problems that could otherwise occur.