In early September, an industrious knitter went to purchase yarn to knit her beloved a pair of socks for Christmas. She purchased a few balls of Regia Kaffe Fassett yarn in a suitable colourway from a local yarn store and merrily cast on. She took her newly started sock to a hockey game and worked away, wondering all the time why her fingers felt sore and why the sock looked a little big. “I’m using sock yarn and this is the recipe I always use, so it must be right,” she thought to herself.
The next morning the knitter began to doubt the sock, the problems she had ignored the night before were still nagging at her, so she went to Ravelry to check on her yarn and discovered it was a DK weight sock yarn and not fingering weight. This presented a conundrum; she had the recipe for fingering weight yarn, but not DK weight. She came up with 2 options, either do a bunch of math and hope that the DK weight socks would fit or buy fingering weight yarn for Christmas socks, knit those socks based on the recipe, and then knit socks in the DK as Birthday socks using the fingering weight socks for reference. She decided to go with the second option and off she went to buy more yarn.
She knit and knit and knit some more on the new yarn, a fun Drops Fabel colourway called Carnival, until she had a pair of socks ready for Christmas. There were still 6 weeks until Christmas, so she felt that she had plenty of time to knit at least one of the socks in the heavier yarn using the Christmas socks as a template. She cast on the toe and increased until it matched the other sock perfectly. As the sock grew there was a niggling in the back of the knitter’s head that said, “It looks a bit small”. She ignored the niggle and kept working, after all it was the same size as the sock she knew would fit.
Then one fateful night a few weeks before Christmas she went to measure the length of the sock to see how far she had to go until the heel turn. On a whim, she tried it on, just to settle the niggle for once and all. It fit. It fit on her foot and it was just about ready to turn the heel… if she was making them for herself. She had forgotten that the thicker yarn meant that the socks needed to be the same internal size, not the same external size. So again there were 2 options, either rip back to the toe and add more increases or finish the socks for herself. She decided that getting the yarn to work for a pair of socks for her beloved was not worth the frustration and resolved to buy more fingering weight yarn for his Birthday socks. Also the colours were really nice and she didn’t have any socks in those colours and the thicker socks would be nice to wear to hockey games. So she turned the heel and made the socks to fit her feet. Within a few weeks she had a new pair of socks completed and the opportunity for more yarn shopping.
The moral of the story is that both the interior and exterior of a project will not match up if the yarns are different weights.