There could be many reasons why you don’t want to/can’t use the yarn that is specified on a pattern. It could be too expensive, not in your colour or the worst, discontinued! This guide will lead you through finding a yarn that will work with your pattern.
Tension (gauge) is vital otherwise you won’t end up with a jumper that fits you or a giant tea cosy or another disaster. If your pattern calls for a yarn in a standard weight i.e. 4 ply, DK, Aran etc then this shouldn’t be too much of a problem. It’s still worth checking the actual tension of a yarn as some that have names that include ‘DK’ or ‘Aran’ sometimes aren’t the standard tension. It’s always worth doing a tension square to make sure your new yarn will work up the same as the one recommended in the pattern.
Working in a yarn shop for so long has shown me that this is the biggest mistake people make when swapping yarns. 500 g of one yarn can have a vastly different yardage than 500 g of a yarn in a different fibre or brand. Always check you have enough length to complete your project, a quick google or check on Ravelry can tell you what lengths most yarns have and then multiply by how many balls you need. Divide it by the length of the new yarn and round up if necessary. This might mean you only have to buy 400 g instead of 500 g 🙂 or it could mean you have to buy 600 g… Don’t put too much store in the weight the pattern tells you, length is what is important.
It is also worth thinking about the texture of your yarns. For example if your pattern is in a fluffy yarn it could lose something if you do it in a smooth yarn. Patterns that use fluffy yarns like Rowan Kidsilk Haze often rely on the fluff to ‘fill up the gaps’ meaning that if you use a smooth yarn it might look a bit gappy.
Some stitch patterns can be lost in dark colours or variegated yarns, don’t lose all your hard work by using a yarn that hides it! If you are choosing a whole new palate for a colourwork project try to chose colours that blend/contrast like the original pattern if you are after the same effect. But really colour is entirely personal preference, knit what you enjoy!
4. Fibre content/drape
There is nothing wrong with choosing a different fibre for your project but it may make a difference. For example, using a solid wool for a waterfall style cardigan originally made in cotton will make it fall differently. This might not be relevant for say, a tea cosy, but bear it in mind for garments and blankets.
You may also need to think about the fibre content in terms of what the project is, socks in pure silk would be beautiful but won’t last very long! Most sock yarns have a small amount of nylon in for strength for this reason. Lots of colourwork projects are done in wool as it is easier to make it look neater than using cotton. This won’t matter for a lot of things, but again, something to bear in mind. I tend to use a similar fibre content when I’m substituting yarns, the designer picked it for a reason!