Knitting, math, and rules of thumb

Recently I have been reading about the history of knitting (more to come on that in future posts). Looking at the gorgeous, intricate sweaters that were knitted by ordinary people in earlier centuries makes me wonder: how on earth did they design these sweaters without a hefty dose of algebra and geometry, let alone long division and multiplication tables? Personally, it takes me graph paper and a calculator to design a sweater or to alter a pattern for a different size.

I discussed this with my dad over brunch the other day, and he suggested that many craftspeople in earlier eras used simple “rules of thumb” to figure out problems like what angle to set a roof at — problems that without the rule of thumb would involve complex mathematics.

I had a little fun today, googling “rules of thumb” to find some modern guidelines for knitting and crochet:

• To get a neckline to lay flat, knit 2 stitches together in first round at each shoulder (here)
• When knitting with ribbon yarns, use smooth, blunt needles (here)
• When substituting the yarn used in a pattern, wool can substitute for cotton, but cotton does not substitute well for wool, especially in cabled patterns (here)
• If a social function requires you to hold a cup of tea or a martini, it is best not to knit (here)
• The fuzzier the yarn, the harder it is to crochet with (here)
• To pick a needle size for knitting with handspun, select a needle that is the same thickness as two strands of the yarn lightly twisted/plied together (here)
• Crochet requires 30% more yarn than an equivalent knitted pattern (here)
• You can determine the double-stranded gauge of a yarn by multiplying the yarn gauge by 0.72 (here)
• Hold your crochet hook like a pencil for precision and control, or like a knife for looser tension (here)
• And my favourite: If it serves no purpose, don’t do it (here)

Most of those don’t sound like the kind of rules of thumb that would allow you to design a fair isle sweater “off the cuff” though (haha).

And here are some knitting books with rules of thumb. I’m not aware of any similar books aimed at crocheters, although you can apply many of the techniques as long as you account for the different height and width of crochet stitches.

• Knitting Rules!: The Yarn Harlot’s Bag of Knitting Tricks
• Knitting in Plain English
• Knitting Without Tears

More to come on this…