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  #1  
Old 01-18-2021, 04:24 PM
JParrilla JParrilla is offline
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Default Is this too much belly?

So, I recently bought this Cordoba off a forum member here and I have been very obsessive about keeping it humidified since it came with a crack in the poly and I wanted to make sure it stayed that way and didnt progress to the actual wood.

I have been putting 2 damp sponges in perforated ziploc bags in the case with the guitar (one in the soundhole, one behind the headstock). My room humidity is 35 right now so I figured this was the only way to keep it humidified.

Now I am noticing that the bridge is bellied, but I have no idea if it was like this when I got it. In your opinion, is this an acceptable bellying? I would say that there is close to a 3/16" gap on either side from the ruler when I lay it behind the bridge. Im wondering if I should lay off the humidifying and just leave it in the case without anything or just keep it out on a stand.


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Old 01-18-2021, 06:47 PM
RonMay RonMay is offline
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Default don't over humidify

Jerry Rosa of Rosa String Works explains humidity very well here.
The talk about humidity starts about 12:58 min.


https://www.youtube.com/watch?v=7REvPRcyTmI



Ron
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Old 01-18-2021, 09:15 PM
JParrilla JParrilla is offline
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Quote:
Originally Posted by RonMay View Post
Jerry Rosa of Rosa String Works explains humidity very well here.
The talk about humidity starts about 12:58 min.


https://www.youtube.com/watch?v=7REvPRcyTmI



Ron
Interesting. I always assumed if I didn't add humidity it was just a countdown to cracking. May have to rethink
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Old 01-19-2021, 12:29 AM
mirwa mirwa is offline
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Stop humidifying it, if you do not know what the moisture content is in the wood, your doing as much damage as allowing it to dry out.

Buy a Boveda control pack or something like that, it will maintain a consistent humidity around 50 percent

Steve
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  #5  
Old 01-19-2021, 12:47 PM
JParrilla JParrilla is offline
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Noted. I took it out of the case entirely... leaving it out in my room for now. I have a digital hygrometer in the room that reads between 35 and 40 but honestly I cant be sure its calibrated.
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Old 01-19-2021, 12:48 PM
John Arnold John Arnold is offline
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Wrong approach. Most finishes are thermally sensitive, while wood is moisture sensitive. Humidifying will swell the wood, which in extreme cases, will craze the finish even worse.
Placing the straightedge behind the bridge, Martin spec allows for up to 1/4" of belly on each side, or a maximum of 1/2" when adding the two measurements.
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Old 01-19-2021, 01:35 PM
charles Tauber charles Tauber is offline
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Quote:
Originally Posted by JParrilla View Post
Interesting. I always assumed if I didn't add humidity it was just a countdown to cracking. May have to rethink
I couldn't make it through the video, even at twice normal speed.

As John implied, you are approaching it with an incorrect understanding.

Wood absorbs and desorbs moisture in response to changes in the humidity of its environment. As it absorbs moisture it expands. As it desorbs moisture in contracts (shrinks). As it expands and contracts, it changes geometry - size and shape. The changes in size and shape can change playability and, usually as a result of drying, can cause the wood to crack.

Most guitars are made in a controlled environment, typically around 70 F and about 40% or 45% relative humidity. Ideally, one would maintain the environment of the finished instrument at the same environmental conditions as it was made. Doing so ensures that the geometries don't change (due to humidity fluctuations) and reduces the chances of the woods cracking.

The further one deviates from the conditions at which the instrument was made, the greater the probability of undesirable consequences. As humidity levels increase, tops swell and increase playing height. Extremely high levels can lead to glue failures, mold growth and cracking finishes. Many find that at humidity levels above 60% or so, guitars sound muffled, as if "stuffed with socks". As humidity levels drop, tops flatten and decrease playing height. Extremely low levels can lead to woods cracking.

Again, the ideal is to maintain an instrument at a constant humidity level, the same as that at which it was made. That isn't always possible.
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  #8  
Old 01-20-2021, 11:41 AM
tokairic tokairic is offline
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Default belly or top radius?

It looks to me as though by measuring across the top you are measuring top radius. Many guitars are built with a radius in the top and back. I build mine with a 15 foot radius on the top which gives about 4mm clear at each edge measured the way you are doing it.
I would measure belly by putting a straight edge from the end of the fretboard to the bottom of the body, obviously alongside the bridge. Then you can see any dip towards the soundhole and belly behind the bridge.
Slight belly would be normal, due to string tension etc.
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