‘I’m making a baby blanket, so it’s got to be washable.‘

‘It’s a sweater for my son. There’s no way he’ll wash it by hand. I need something that will go in the machine.‘

‘Someone on Instagram said superwash wool is bad. Is that true? It sounds like it should be great.‘

We had to get here eventually.. It’s time to talk about the laundry.

So let’s start with the good news: all the wool in the shop can go in the washing machine. Yes that’s right. As long as your washing machine has either a ‘hand wash cycle’ or a cold wash option, you can wash your woollen knitwear in the washing machine with impunity.

So how do I know that it’s not going to shrink?

Wool shrinks when we introduce 3 key ingredients: heat, moisture and agitation. And the engineering of our washing machines has evolved so much, that most now have a cycle which is cool enough (eliminating heat) and gentle enough (eliminating agitation), to prevent the action of the water (moisture) from felting (shrinking) your woollens. Even old washing machines without a hand wash cycle tend to have a cold cycle which you can use for wool.

So what is the whole machine washable Superwash wool thing all about?

Well having a special cycle which you can use for occasionally washing your occasionally dirty sweater is all great, but if it’s socks or baby clothes you’re making, it might make life easier if they can go in the same wash as the rest of your clothes, and that is going to be around 30° to 40°. So if you’re knitting with wool and you want to make sure that it won’t shrink in your normal clothes wash, you need to use a wool that has a superwash label on it. This means it has been through a special process to prevent our 3 key ingredients from shrinking it when it goes into a normal wash.

What’s the process and what do we think about it?

To understand what the superwash proccess does to wool, we first need a brief lesson on a critical microscopic property of wool – the tiny, invisible to the naked eye, hooks that sit on the surface of the fibres of the wool. These hooks are loosened and opened up when they get wet. And when they’re hot and agitated they hook onto each other and grip each other tightly, making the fibres felt together, which causes woollen fabric to shrink. There’s a fascinating and more detailed explanation of all of this in this marvellous Modern Daily Knitting article on Superwash.

The processes for preventing wool from shrinking are all based on inhibiting those hooks and stopping them from catching onto each other. Using chemical engineering, the superwash process either strips out the hooks or adds a coating which will smother them to stop them latching onto anything.

So why don’t we just put all our wool through that superwash process?

Because it takes something away from the nature and character of the wool. Superwash wool lacks the technical integrity of non-superwash wool. It won’t be as toothy or as grippy. Basically superwash wool feels, well, just a bit less woolly. Over time, garments made from superwash wool can slightly lose their structure and body, as the fibres become a bit flat. On the other hand, garments made with superwash wool are more likely to be washed when they get dirty and that might make all the difference in terms of them being useful items of clothing. Beautiful hand knitted socks are much nicer on feet than waiting in a laundry basket for a special wash day.

And what about the detergent?

Ordinary non-gentle detergents use two active ingredients to clean the dirt from our clothes: surfactants which are the soapy part for general cleaning, and enzymes which attack proteins (because proteins are what stubborn stains are usually made of). The trouble is that wool is also a protein and when you wash it with these detergents, the enzymes can’t necessarily tell the difference between which proteins to have a go at. And that’s why wool needs a gentler detergent. We have a lovely enzyme-free eco-wash made by the Clothes Doctor, which is scented with moth repelling herbs, but there are plenty of others available. Just look for the ones which say they’re suitable for wool.

And finally, what if I just don’t trust the machine and would rather wash by hand?

I get it. You can control the temperature, you can gently work off that bit of egg yolk from yesterday’s breakfast, or perhaps you get a profound feeling of well being looking down at your bathing woolly beauties. Whatever the case it’s fine by me and your socks too. Given how gently they’d be dealt with in the washing machine, you’re likely to get them at least as clean if not cleaner, by hand. You just need to be careful about how you lift things out of the water at the end. Sodden sweaters are heavy, and the fabric can easily get stretched out of shape, so avoid lifting your sweaters out of the water by their shoulders. Get rid of as much moisture as you can in the sink, and then place your sweater in a colander to lift it out. Whatever you do, don’t wring out the fabric in the twisty way you would with cotton. Excess moisture can be removed by rolling it tightly in a towel or spinning it in your washing machine. Once your woollens are damp, rather than sodden, you can lay them out to dry, preferably flat.

Then sit back, admire your work and have a nice cup of tea.