Going sharp

[Nubus]

Why do some guitars go out of tune sharp? I understand them falling flat but getting tighter after a song doesn't make sense to me.

[dagosto]

There are three ways that I know of for a string to go sharp. One is if the string is bended down (with a tremolo or by bending the neck) it can get caught in the nut before it is bent back up so the tension behind the nut wold be less than in front of it.

The second way is if you tune a string up the friction of the nut can keep the string from moving as much as it should causing th tension behind the nut to be higher behind it than in fron of it. Then as you play that the string vibrates and moves in the nut a bit, allowing some of the tension to transfer to te front of the nut. Both of the previous ways can be avoided by lubricating the nut with graphite when you change the strings.

The third cause of a guitar going sharp is thermal expansion. Bringing a guitar in from the cold, your body heat, or heat from lights on stage are all possible causes of slight expansions in wood and can translate to bigger tuning issues.

[Nubus]

Ah, that makes more sense to me now. I mentioned drawing in pencil there but I couldn't explain why. TY. There was a Bigsby involved so I bet it was a little 1 and 2.