Arch tops & Mandolins go sharp

[rgregg48]

It seems arch top guitars and mandolins
When stored in 45% humidified room
Tend to go sharp and need to be tuned down
Every time I play.
Anyone know why?
Thx
Rick

[icuker]

I notice that with weather changes also. usually when it's colder outside my mandolin and guitars will go sharp. I do believe the archtop is more prone but it also happens with my flat tops, but not all of them.

[Mandobart]

A'll my instruments (20+) are stored in the open, in my insulated, humidity and temperature controlled basement music room. Temperature varies from 68 F to 71 F. Relative humidity varies from 40% to 46%.

All my fiddles (2 violins, 3 large violas) are of course arch tops. They are darn near rock steady in tune regardless of changes in temp/RH.

I have 8 mandolin family arch topped instruments, a sel-mac guitar (sort of arch top) an archtop guitar and these are fairly stable. If humidity rises they may go slightly sharp due to wood expansion. My resonator mandolin (wood body, single cone, spider bridge) doesn't drift much. My two banjos don't follow any clear rule - just know they need frequent retuning.

My flattop guitars (3) seem to go slightly flat over time regardless of temp/RH. Same with solid body electrics.

[Steve DeRosa]

Originally Posted by Mandobart

...My two banjos don't follow any clear rule - just know they need frequent retuning...

I hear there's a banjo player who finally found the secret of playing in tune...

Services are 11 AM tomorrow at Pinelawn Memorial Park...

[OKCtodd71]

Humidity and temperature work in concert (see what I did there) on the wood of an instrument and when either one or both change the wood shrinks or expands causing strings to go flat or sharp. Fwiw, I do find that my carved spruce top archie is more sensitive to these changes than my Les Paul.

[55tele]

If you are humidifying, they tend to go sharp....

What I find is that when the neck relief is less due to higher humidity, there is more string tension and tuning goes sharp