Steam Blocking Acrylic Yarn

My favorite way to block any project is with steam. It’s a fast, easy and clean way to get your project to the correct size, make it lay flat, or just make it softer. The tutorial below will show you the basic steps for blocking acrylic yarn with steam. I also have a full video tutorial available here.

I’m going to show two different uses for steam blocking in this tutorial:

1) how steam can make your project magically lay flat

2) how steam can help you achieve the correct size for your project.

Acrylic Swatches
I will make the left swatch lay flat and the right swatch bigger by just steaming.

First I will show you how steam can flatten out a curling project. Sometimes when crocheting, for whatever reason your project will curl on itself. Sometimes it’s because of the stitch you are using, or it can result from a tight gauge, or many other reasons. Whatever may be causing the curl, steam can be used to help relax the stitches.

In order to steam block you will need a few things.

1) a steam iron or garment steamer

2) a steam/water proof surface – you can use a blocking board, an ironing board, or a simple towel

3) rust proof pins

Important Note: The pictures below show me using my hands with the steam iron to make the swatch lay flat. This is done to show how the steam makes the piece lay flat (see the video for how this works out). You should pin down the pieces before putting steam on them so you do not burn yourself.

First, place your project on your steam/water proof surface and pin in place.

This piece isn't pinned down so in the video you can see how it "magically" lays flat from the steam.
This piece isn’t pinned down so in the video you can see how it “magically” lays flat from the steam.

Next, get your steam iron or garment steamer and start steaming your project. Hold the iron about 1/2 and inch to an inch away from your project and make sure you don’t touch the iron directly on your project or you will “kill” it (which I will explain further below).

Whatever you do, DON'T touch the iron to the project!
Whatever you do, DON’T touch the iron to the project!

Keep steaming the project until it is laying flat. You will notice it will feel warm and slightly damp to the touch. It will also soften up considerably. So if you have a scratchy acrylic, steam blocking can make it much softer.

Almost completely flat just by steaming.
Almost completely flat just by steaming.

If you happen to touch the iron to the swatch, this is what will result. A flat, slightly melted shiny fabric. It is what is commonly called “killed acrylic” and sometimes it is desired because of the look it produces. If you want to kill your acrylic be careful not to hold the iron on the fabric too long so it doesn’t completely melt into goo. Remember, acrylic is essentially a form of plastic, so it will melt like it with too much heat.

This swatch was touched by the iron and melted slightly.
This swatch was touched by the iron and melted slightly.

The other use for steam blocking is getting your project to the correct size. This can be used in conjunction with getting your project to lay flat.

For example, you are making a garment and need it to measure a certain size to fit, or you are making an afghan and need all the blocks to measure exactly 12 inches on each side. Using steam and pins you can make these things happen.

You will need the same tools as before and also a measuring tape. To show you how much you can stretch a project with steam, I’m starting with a 5 inch block.

I'm going to see how far I can stretch this swatch.
I’m going to see how far I can stretch this swatch.
Notice the pins are almost flat. This allows my iron to get close enough to let the steam do the work.
Notice the pins are almost flat. This allows my iron to get close enough to let the steam do the work.

Once your project seems warm and damp all over (which means the steam got into all your stitches) allow the project to cool and dry completely before unpinning. You need it to cool and dry for it to hold it’s shape, so don’t get antsy and unpin right away.

Here I begin to unpin, notice the piece isn't moving as I unpin (as in, it's not springing back to it's original size, so the steam worked).
Here I begin to unpin, notice the piece isn’t moving as I unpin (as in, it’s not springing back to its original size, so the steam worked).

If you notice your project isn’t holding it’s shape as you unpin, you might not have used enough steam. Don’t be afraid to re-pin and steam some more. It might take a couple of times steaming before you find how much steam you need to use to get your projects to hold. Once you get it though, it’s like riding a bike.

I got an extra 3/4 of an inch out of my swatch!
I got an extra 3/4 of an inch out of my swatch!

As you can see above, I got a whole 3/4 inch extra width on my swatch. Plus the steam made it very soft.

I’ll be added more ways to block in the coming weeks so check back to see if I’m covering a new way you’ve been wanting to learn about.

If you have any extra pointers about steam blocking I’d love to hear from you, or if you have a method you like better let me know below. I’d love to hear your feedback!

24 thoughts on “Steam Blocking Acrylic Yarn

  1. Coca cola is supposed to soften stiff fabric like denim, I wonder if it would soften stiff acrylic yarn. The procedure is to wash the fabric in the washer with a can of Coke added. I bought some Coke but I haven’t tried it yet. The yarn I can buy nowadays is so rough, back in the 60’s and 70’s acrylic
    yarn was much softer.


  2. Great article on steam blocking acrylics ~ thank you! I’m going to save it for when others say you can’t block acrylic, because you CAN. The only thing I would add is, if your iron has a “shot of steam” feature, DO NOT use it; it is too much hot steam in a concentrated area, and you will kill the yarn under it (I refuse to discuss how I know this – :/)

    Liked by 1 person

  3. I tried to put iron on denim on the bottom of crocheted slippers. I burned a hole in the slipper so it’s ruined. Do you have suggestions for cleaning the iron? It’s got a big gooey mess of melted yarn on it. :-(.


  4. What kind of pins do you use? I’ve used some with white balls on the top and they leave rusty marks on my projects.


    1. I usually use specific blocking pins from sites like However, you can also purchase regular sewing pins from Joanns or Michaels. Just be sure they say “rustproof” on the package. 🙂


  5. I have a large bulky afghan that has a lot of curl in it. I want to use it to cover my ragged sofa. When stretched flat the afghan covers the entire sofa, but when it curls it is too small. I want to use my steam cleaner to stretch, as well as shape, the afghan to fit the sofa.


    1. that could work if you can pin it straight to the sofa and steam it there, it should mold pretty well to the sofa. Just make sure not to touch the blanket directly if it is made of acrylic. 🙂


    1. It depends on how good your steam is. If it is strong you will probably only need to let it sit for about 5 or 10 seconds. An iron with less steam will take longer. Just keep checking it and stop when you like how it looks. 🙂


  6. Thank you very much! I will try that out as soon as possible. And thank you for the tip about trying it with a test piece first – I wouldn’t have thought of that until it was too late. 😉


  7. Can you do this with a regular iron, and just hold it above the finished item? Or does it have to have steam capabilities? (This might be a silly question, but I’ve never blocked stuff before.)


    1. Not a silly question at all. 🙂 You can do it with a regular iron, but you will need to create “faux” steam. So get a damp towel and put it over your project and then press the iron the towel. The damp towel will then create the steam to block the project. Remember though, always do a test swatch with the yarn you are using to make sure you like the results before doing your whole project. 🙂


      1. I’m paranoid of melting the acrylic, so I would use a test swatch to try it out on first. 🙂 It theory it should be fine since the iron isn’t touching it, but you can never be too careful. 🙂


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