Yarns

I've split the info on yarns into 3 sections:

Yarn Types: This covers the different weights of yarns from superfine to super bulky as well as the novelty yarns such as tapes and eyelash yarn. There are also some tips on choosing yarns for new knitters.

Yarn Fibres: The different properties of various yarn fibres including details of what these fibres are like to knit with as well as the properties of the knitted fabric.

Yarn Substitution: Helpful hints on substituting yarns when you are following a pattern but don't want to use the recommended yarn.

Yarn Types

Yarns are classified by their "yarn weight" which has nothing to do with how heavy they are but everything to do with the thickness of the yarn. The table below is a quick reference guide to the different yarn weights.

N.B. The terms two-ply, three-ply etc are misleading, in this context they are historical categories of yarn diameter and don't necessarily have any relation to the number of strands or plies in the yarn. The boundaries between the different traditional weight classes are not set in stone, different manufacturers may label yarn differently.

Never substitute a yarn based on the traditional name alone. Always check the recommended tension and knit a tension square to ensure you can match the tension of the pattern.

Yarn Weights, Yarn Names and Typical Tension / Gauge.

Beginners may be tempted to pick a pattern using a bulky yarn so they'll make quick progress. Sadly many find they are disappointed with garments made with bulky yarn. Manipulating the large yarn and needles may also be awkward. It may be a better idea to pick a small project with a medium weight wool.

Novelty Yarns

Novelty yarns can be tricky for beginners to use and are perhaps best left until you are reasonably confident. With some of the fluffy yarns it can sometimes be hard to see the stitch definition on your gauge swatch. With shiny, slippery yarns it can be difficult to keep a consistent tension. Ribbon yarns can sometimes get twisted up as you knit. Putting the ball of ribbon on a makeshift spindle or inside a narrow box can help ensure it unwinds without twisting. Before starting a project with a novelty yarn it may be worth making a larger than usual swatch, this should give you time to iron out any problems.

If you've got novelty yarn you want to use up, try the Sirdar Loopa. You can make a boa in an evening and it's great for showing off many novelty yarns to their best advantage.

Yarn Fibres

The comments below should give you a general idea of what to expect from the more common yarn fibres, there will always be exceptions and new yarn production methods are gradually ironing out many of the traditional problems associated with certain yarn fibres. It's always worth doing an internet search on your chosen yarn before you buy, sites such as www.wiseneedle.com have yarn reviews, so hopefully you can avoid buying a yarn that has some hidden flaw.

Alpaca: This is a lovely fibre to work with but rather expensive. It is soft and has a slight sheen to it. It doesn't contain lanolin so is often a good wool substitute for those allergic to wool. Some alpaca yarns even claim to be water repellant and flame retardant, we plan to test this out in the Knitting Brain lab.

Angora: Very fluffy and tends to break quite easily. Requires careful hand washing and will leave a trail of fluff until all the loosest fibres have been shed. Some of the more expensive hand spun angora yarns are easier to work with and don't shed quite as much. Not suitable for beginners but the finished fabric looks beautiful.

Bamboo: This is a fairly new yarn fibre, so it's still relatively expensive and the production methods are still being refined. Bamboo yarn is generally lightweight and breathable and is said to have antibacterial properties. It has a sheen to it and is soft fibre. The down side is that it needs careful hand washing: it absorbs a lot of water and becomes more fragile when wet. Bamboo yarn also has a tendency to split during knitting, so you may need to use blunt needles and knit a little more slowly than usual.

Cotton: Lovely and cool against the skin and some brands are super soft too. Pure cotton yarn is made up of many separate plies or threads. This can make it a bit harder for beginners to use because it's easy to stab the needle through the yarn which leaves bits of snagged yarn over the finished garment. Cotton isn't elastic but it is machine washable, hard wearing and often fairly cheap. Because it isn't fluffy, cotton yarn is good at defining stitch patterns. Mercerised cotton has a lustre to it.

Mohair: Fluffy and often sheds fibres like there's no tomorrow. Requires gentle hand washing. The resulting fabric isn't very durable as it tends to pill. It definitely isn't a fibre for beginners, but for the more advanced knitter the lure may be irresistible. You can't beat the look and feel of mohair lace work. The fluffy nature of the yarn gives a kind of glow around the fabric.

Wool: Pure wool may be expensive but it's lovely to knit with and ideal for the beginner, especially single ply yarns. It has an elasticity to it and minor problems with tension and fit can often be solved when the garment is blocked. Wool is also lovely to wear. Wool needs to be properly cared for (see our section on caring for your knitwear) to avoid it shrinking. The tendency for wool to shrink can be used to make felted knits, these can be great projects for beginners - see our knitting project section.

Superwash wool: This can be washed in the washing machine on the wool cycle, some brands can even be tumble dried. Superwash wools can't be felted and it isn't as easy to correct minor problem when blocking, but being able to throw your knitwear in the washing machine is a great boon, especially for children's knitwear.

Synthetic yarns: Novelty yarns aside, these are usually cheap and machine washable. Most have a small amount of stretch to them. The main downside tends to be they aren't as breathable as natural fibres. It may be better to go for a mixed fibre yarn for close fitting garments.

Fibre Blends: These are often great value for money. Look at the properties of the constituent fibres to see if it's likely to have the properties you are looking for.

Substituting Yarns

The usual advice is to knit a swatch and check you get the same tension / gauge as for the recommended yarn. But this advice doesn't help with choosing which yarn to buy.

The first step is to get all the useful info you can on the recommended yarn: Yarn weight category, yarn texture (eyelash,plied etc), length of yarn per ball, fibre content and standard tension / gauge. yarndex.com is a good starting point. The closer you want the finished item to resemble the original pattern the closer the match for the original yarn you should to get.

Look for a yarn with a recommended stitch tension / gauge the same as or close to that for the recommended yarn (the row tension / gauge isn't as critical). Be aware that some yarns quote the tension in stitches per inch while others quote stitches per 4 inches or 10cm. If you can't find this info, then picking a yarn in the same weight category means you should be able to adjust the tension / gauge to match the recommended tension / gauge.

If the recommended yarn is a novelty yarn such as eyelash yarn, you'll probably want to find a yarn with the same texture. You can substitute with a standard yarn as long as the tension / gauge matches, but the resultant fabric will be very different. The converse is also true, you can substitute a standard yarn for a novelty yarn if the stitch tension / gauge matches, but be aware that highly textured yarns will often obscure stitch patterns and the look and feel of the finished fabric will be very different too.

It's also worth thinking about the fibre content too. Take a look at the yarn fibre section and think about how the differences will effect the final product. A ribbed jumper pattern designed for wool can be made in cotton, but it won't be as stretchy or as warm and it will likely be heavier too. Substituting a wool yarn for a wool blend yarn is more likely to give a satisfactory result.

Now you've done all that you can use our knitting calculator to work out how many balls of your substitute yarn you will need. This needs to be calculated from the length of the yarn and not the weight.

Finally, knit a good sized swatch and be honest when measuring your tension / gauge. Don't be afraid to change needle size to get the correct tension / gauge. If the pattern uses more than 1 needle size e.g. a smaller size for the ribbing, but only gives tension / gauge for 1 needle size you might want to use our knitting calculator to estimate the best size to use.