I've knitted with three Opal sock yarns, two single colours from the Opal Uni range (one red, one yellow, both turned into Feet First socks - click on the link for the free pattern) and one self-patterning yellow. The composition of Opal yarns is pretty much constant, and it's the colour ranges that change. One of their most recent ranges was a set of Harry Potter yarns, and others have been based on the colours of rainforest animals, the work of artists and so on.
While the differences in weight of sock yarns are minuscule, Opal sock yarn does feel as though it's at the finer end of the spectrum. This means it makes slightly less bulky socks than some other yarns, especially handdyed ones, although the socks are still chunkier than shop-bought ones. It's also incredible warm, possibly thanks to the wool content. The other component of the yarn, nylon, gives it strength, and my Opal socks have happily stood up to long wearings and repeated machine washings. They've even been through the tumble drier with no change. Some people find the yarn rough on the fingers, but you don't notice the texture when it's on your feet.
Opal sock yarn is definitely on my list of stash staples. I'm not so struck with a lot of the mixed colours and wish Opal had done the Harry Potter yarns in house colours instead of the melanges they came out with. However, Opal Uni is just brilliant. You can use it on its own for single-coloured socks, for heels and toes alongside hand-dyed yarn, for stripy socks... it's brilliant stuff. For around £5-£6 a ball, Uni's hard to beat.
