Tim, that's Temperament, not temperature! It's nothing to do with the temperature of the strings, it's to do with the physical properties of pieces of wire of differing circumference but approximately similar length, and the effect on pitch that occurs when shortening them by capoing and/or fretting them! They all go sharp, but by differing amounts, so the guitar slowly goes out of tune as you work further up the neck. A guitar can never be 'in tune' at all positions on the neck because it has strings of differing thickness with frets in fixed positions - it's a physics thang!

'Averaging out' the variances involves a system of tuning called 'Tempered Tuning'. As you shorten the length of the strings by capoing, you need to temper the tuning to take account of these small differences, and that's what we're doing when we tune, slap the capo on, then tune again (maybe it's not a conscious thing with all performers, but they're doing it nontheless!). Told you it was complicated! I'll talk to you next time at MRFC. (Apologies if I'm teaching me granny to suck eggs! LOL!)

Regarding teeth-grinding time, I guess that I'm used to listening to people waffling on about the song they're going to sing, so I regard that as part of the performance, and quite acceptable.

Cheers & Beers M'Dears
S:0)