Thin strings (eh?)

Tannin

Why is it that you can have two different sets of strings in the same material, in the same gauges, and with reasonably similar tensions, but for some reason I am completely unable to explain, Set A will feel as though the strings are quite thin, while Set B will feel thicker? 

To exaggerate a bit to explain what I mean, it's as if Set A is high-tension 11s, while Set B is low-tension 13s. One wants to cut into your fingers, the other does not. One gets a bit flubby if you hit too hard with your right hand, the other is more forgiving. Both sets have the same tension (more or less) and both are specced as 12s. I don't have a micrometer, but there seems no reason to think that  either set's 53 E string is really thicker of thinner than spec. It just feels thin on Set A. Why?

I've been puzzling over this for a long time and have got nowhere. Over to you, brains trust.

(PS: one hint - often (but not always) cheap strings feel thin, and often (but not always) expensive strings feel thicker. Relevant?)

drofluf

A difference in the core/wrap size ratio and the relative densities of the materials involved?