How to Block Acrylic!

Hello all!

So I originally posted a tutorial ages ago on my personal blog about how to block acrylic, now, welcome to the updated edition!

This started when I had to block a pair of socks that were partially made from acrylic sport-weight.

Side Note:  Acrylic -does not- work for socks.  An acrylic blend might work out alright depending on the exact blend; but straight acrylic doesn't breathe at all and is completely not suitable for socks. (I'm never doing -that- again).  These socks are partially acrylic and partially wool, so they're wearable, but still not something I would do again.  

Anyway, I had to block these socks, and I kept hearing that you couldn't block acrylic.  But these were colourwork socks, and really needed blocking.

So, more research lead me to the concept that you can steam-block acrylic.  But I don't have a garment steamer; my sock-blockers are plastic and I was worried they would melt; and I'm not the most coordinated person, and didn't want to drop the iron on my newly finished socks.

Here is my solution.  However, please note, this solution only works well for fabrics that sit flat (lace, colourwork).   Textured knits, like cables and heavily textured patterns, can lose some of their texture with this method. 

You will need:

  1. Two towels
  2. An iron (steam setting helpful but not required).
  3. Water
  4. Whatever you're blocking. (In this case, the first of a set of Pacific Rim Socks by Sonja Launspach.)

A slightly blurry picture of a single colourwork sock.

Step One:    Take your knitted object and get it wet.  Soak it through with cold or room temperature water.  If it's a bigger or thicker project, you'll have to immerse it in water and make sure it's soaked through.  A bucket works well, or the bathroom sink.  Try not to jostle it around too much, you don't want to risk felting any natural fibers that you've used.

Step Two: Lay one of the towels flat on a solid surface (here I'm working outside on my balcony).  Place your knitted object flat on the towel.   Then, cover it with the other towel.

A colourwork sock laying flat on a towl.  The sock is slightly puckered.

Step Three:  Iron the object with the towel over top. Use the lowest possible heat, and use the steam setting if you have it.  If you don't have a steam setting, keep a small bowl of water at hand, and pour it onto the top towel in small amounts, making sure that it soaks through both the towel and the knitted object.  The heat from the iron will convert the water into steam.  If you find that the heat from the iron isn't getting through the towel, increase your heat by a tiny amount and try again.

A towel being steam-ironed on a flat surface
Step Four: Continue ironing until your finished object is to the dimensions you want.  If you have metal pins or sock blockers (anything that can stand up to the heat), you can use those to help you get to the right dimensions.

Never touch the iron directly to the object!   Always have the one layer of towel between your knitted object and the iron.  This is so you don't accidentally scorch your knitted object.

A sock placed between two towels.  One towel is folded back, exposing the cuff of the sock. The tip of the steam iron is where the towel has been folded back.
Here you can see that I'm ironing up near the cuff.  I've pulled back the towel so I can see what I'm doing and I don't accidentally over-block the sock.

Step Five:  Once you do one side of your object, pull back the towel and press the other side of the object, if necessary.

Step Six:  Work slowly and check your work often. Blocking acrylic is permanent, and cannot be undone.   What you're basically doing is melting the plastic of the acrylic ever so slightly.   If you over-block acrylic, you 'kill' it, and you get a superbly drape-y and non-elastic fabric, which you only want for specific objects (and in this case, a sock would not be one of those).  And, because this particular sock has some natural fibers in it, it would cause major problems, since the wool would block out differently then the killed acrylic.   

The colourwork sock being worn.  It now is flat and fits perfectly to the model's foot.
Step Seven:  You will eventually end up with a blocked, finished object, ready to wear!  Wear your object as soon as you can stand the heat, to avoid any pleats from the ironing process.

And finally, since no tutorial would be complete without a picture of my dedicated assistant, I present to you, my assistant, general troublemaker, and lover of blocked objects:

A grey tabby-cat, stitting on the blocked colourwork sock and towel. The cat is looking right at the camera.

Anyway, I hope this is a helpful guide on how to block acrylic (and mixed-fiber) projects. Again, please note that this technique doesn't lend itself as well to textured and cabled knits, because they can lose some of their texture in the ironing process.

If you're looking for more information and guides on blocking, you can find lots of information in this Ravelry Thread (though the thread is long enough you'll probably have to take advantage of the search function).  If you've got specific questions about this tutorial (or about blocking in general), please don't hesitate to ask questions here on the blog, on Ravelry, or by E-mail (


  1. An interesting article. I must say I haven't tried blocking acrylic but I feel less fearful now that I will melt it. The color work on your socks is super!

    1. That's what the towel is for, to help prevent you from melting it by accident.

      Just start with the lowest heat possible on your iron, and if you're still concerned, you could even use two towels between your knitting and the iron. So long as you don't get impatient, you should be perfectly fine.

      And thank you for the comment on my colourwork. It was the first 'advanced' knitting skill I learned as a kid, so I still quite like doing it. :)


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