From my understanding of plastics the strings are not operated in their plastic phase.
The stretching we observe during their settling is just a longitudinal reorganisation of the makromolecules. Some kind of relaxation process. It will just marginal reduce the diameter and has very little to no impact on the unit weight as the density goes up accordingly. This being said under the provision that the string's load is well below their yield strength!
Anyway from a pure logical perspective I support to measure the string's tension at the pitch they are intended for. Why not, when considering a new and standardized setup!?
Prominent Critic wrote:Perhaps D'Addario and the other string companies are already using some analogous device. It's certainly possible. It's also possible and probable that they're using some theoretical formula to calculate what should be the tension given all the factors they input. Since that method of calculation sends rockets to the moon, I don't see why it shouldn't be used - and successfully - for something as relatively simple as measuring the tension of a guitar string. The problem is to get all the string manufacturers to adhere to a uniform standard for the calculation.
D'Addario has done that just recently by changing their tension values. The new values are now in full compliance
with Mersenne's law with a density of 989 g/dm³ for ALL (!!!) treble strings.
Opposed to this the backward calculation of the old tensions results in different densitiy figures for every treble string which is not reasonable: 933 (e1), 952 (b2) and 1008 (g3)
Other brands are even worse: La Bella 2001 MT: 876 - 994, Hannabach 815 LT: 954 - 1169
So refering to the other thread which originated this one here, the answer is, nothing changed with the good old EJ45 strings except the calculation and most presumably the subjective tension perception influenced by different figures!
PS: BTW there are automatic tuners around which seem to operate very satisfactory. I suppose they would be perfect to bring and keep the strings automatically in tune! The keyword for google is tronical!
So the test bench could be something like a monochord with load cells or spring balances on one side and tronical tuners on the other side!