Sometimes when I have a knitting project in the queue but don't have the correct yarn for the job I'll resort to combining two strands of a fingering or lace weight yarn to arrive at an aran or DK weight. And I've seen other knitters knit with two strands to achieve a marled effect, too. Until recently I only ever did this out of pure necessity but the results have so many pros that I'm definitely going to take it into consideration when planning projects from now on.
Lastly, if you're knitting with a hand dyed yarn you can knit with two stands of a finer yarn to arrive at a bulkier weight and avoid pooling by joining the two strands at different points in the colourway (Not to say their aren't ways to do this when knitting with a single strand.) Last month when I test knit this Moonstone Cloche by Abbye Dhal in two strands of Malabrigo sock yarn. There are greens, reds and purples in this colourway but they didn't pool at all - although I was less on top of where the two strands joined in the colourway when I picked up stitches for the crown.
Also, I suspect that there might be an economic benefit to knitting some yarns in this way in terms of gaining yardage or avoiding buying too many skeins ie. if you know you'll have half a skien left over when knitting your garment with a DK weight yarn you can eliminate the "waste" (I have so many unused half-skeins!!!) by buying one skein of fingering weight yarn to divide into two and knit in a double strand (instead of two full skeins).
Okay now for the CONS...
For me there is only one CON, but it is kind of a big one. I find that I have to really pay attention to make sure that I'm always knitting in both strands. A pointy knitting needle will help with this, but the knitting is a bit less mindless when knitting with a double strand. When I do miss a strand it appears as though there is a hole in my knitting and I end up having to 'repair' them with duplicate stitch if I don't catch them while I'm knitting. The duplicate stitch does the trick, though, so at least there's an alternative to frogging or dropping back to that stitch.
Okay, I lied! I have one more thing to add that might be considered a con. My one point against using a double strand for structural things like hats is that the thinner fabric may take away from the structure of it, which I did find with the crown of this cloche hat. The body of the hat is knit in linen stitch which is super dense due to all the slip stitches, so I did not find it made a fabric that is too floppy, but I could see that being the case for other hats in regular knit and purl stitches.
Do you ever knit in a double strand? What do you like/dislike about it?
Janna Maria Vallee is a tapestry weaver, longtime knitter, and 2013 graduate of Concordia University's Fibres and Material Practices program. In her art practice Janna combines textiles and socially engaged media. She founded VY in 2008.