Mandolin goes sharp?

[icuker]

On most of my instruments the strings tend to go flat if sitting. My mandolin tends to be sharp when I go to tune it. I'm thinking that means that the neck is being pulled up toward the bridge?

I've had it for two + years (it's an Eastman 505) and last year I had it looked at by the store I bought it from (it's a 6 hour round trip, so I don't do it a lot) and they said the neck and all was very good and straight, so I am not worried about it, just wondering on the physics of it all.

Rus

[Gene Korte]

Sounds more like a string thing. But doesn't make sense it going sharp in this weather.

Typically, when the weather gets hot the strings stretch and the instrument goes flat, but your situation is just the opposite. Are you taking the instrument from a warm/hot environment to a colder/cooler one?

[icuker]

No, I'll just leave it out for days leaned up against something. It's usually in the same room and we run the A/C in the summer. That's why it baffled me. I re-tune every couple of days.

[Pete Summers]

Sounds more like a string thing. But doesn't make sense it going sharp in this weather.

Typically, when the weather gets hot the strings stretch and the instrument goes flat, but your situation is just the opposite. Are you taking the instrument from a warm/hot environment to a colder/cooler one?

Mandolins, being wood, will absorb moisture in humid weather. The absorbed moisture causes the wood in the top (and back also -- all wood) to swell slightly, thus putting more tension on the strings, causing them to go sharp. This is a normal result of a wooden instrument in humid conditions. It is the major cause of pianos going out of tune in the spring and fall months.

Normally, air conditioning removes a lot of moisture from he air, but there is still some that can be absorbed by the wood in your mandolin.

I'd just tune it every day instead of every couple of days. In fact, checking the tuning everytime you play it is a good idea, IMO.

[icuker]

Yea, I get kinda lazy about that! Too many strings and not much room between tuners.

Thanks for the explanation, that seems to make sense.

[JeffD]

All my mandolins can be counted on to be out of tune next day.

[mandroid]

my Carbon fiber Mix does not absorb moisture , so stays in tune for a long time.
+1 on the relative humidity effecting wooden things..

[Mike Bromley]

Yup, it's the moisture. I take a solid mando over to Iraq and by the time I get there it has gone almost a semitone flat from all the dry air in airplanes, airports, and the arid, air-conditioned atmosphere at my destination. I stuff the case in a big garbage bag with a moist sponge, and 24 hours later, it's back to normal, or so. So far, no loud, ugly banging noises from cracks or seams....