The question popped up in connection with testing of a pattern of mine. It is about this sweater.
As you may know, Aade Lõng 8/2, 100 % wool, 100 g/400 m. Based on that, you could think that quite a lot of sock yarns will do the job. However, some testers took a yarn in a similar weight and did not get the right gauge. What is wrong?
The blue yarn is Superwash BFL Sock Yarn (RebelYarn), 100 g/400 m, pure wool. The purple one is Aade Lõng 8/2, also pure wool and of the same weight. Of course, fiber matters (compare mohair and wool of the same weight) but not only this. Here you can see that Aade Lõng is more airy, not so even and not so tightly twisted. Therefor, one should look for a slightly thicker yarn and certainly with a relatively weak twist. One of my test-kniters has established that Baby Alpaca Silk by Drops suits well (50 g/167 m). Yet another candidate is Yorkshire Tweed by Rowan, 25 g/110 m. We shall see whether the right gauge can be achieved with it but in general I think the yarn choice is right (not very densely twisted, airy).