Yarn Over: Blocking Acrylic

It’s my personal belief that every knitter will eventually learn more about the mechanics of knitting just through knitting itself, if you’re willing to look for little lessons to learn. Knitting has taught me quite a lot of these small things over seven years of doing it; Yarn Over is just a couple of those tips.

They say it can’t be done–it’s plastic, you’ll kill it–doesn’t have the same properties as natural fibers–it’ll all be wrecked–but have you ever tried it? Only listened to these dire warnings? Yes, I’m here to tell you it’s possible: you can block acrylic.

Unlike wool, angora, cotton (!), hemp, and countless other yarn fibers, which are all animal- or plant-based fibers, acrylic is a synthetic fiber. More simply, you can think of it as plastic. This is the main reason people say you cannot block acrylic; because they think the heat will melt the knitting to create a shiny, dried-looking melted piece of plastic. (They term this “killing the acrylic,” although I assure you you can avoid the horror.)

I like to steam block my acrylic projects, since it’s a relatively quick and easy method. The other main option for blocking acrylic is wet blocking. Although it is nearly as easy, it isn’t always as effective. I’ll go over both methods in this post.

If your project’s shape and size is satisfactory, you can proceed right to applying the water. However, the magic of blocking is that you can stretch and reshape the project while it’s wet, and it’ll permanently keep its shape (yes, even through washing and drying!). It’s amazing how much extra length you can stretch out of a too-small project; depending on how large it is already, you can get anywhere from 2 to perhaps even 5 extra centimeters. This also largely helps out with regulating the sizes of squares for a quilt or similar projects with units to them.

Another thing that blocking helps fix is those annoying curling and non-flat projects. For example, the very nature of stockinette stitch is to curl up and just be generally disagreeable when it comes to lying flat. Blocking will help fix that. Applying moisture, and if using steam, heat, will relax tight stitches and and even out the yarn, allowing it to lie flat. Of course, one needs to consider the flip side of the flattening effect–blocking will flatten any texture you’ve got, so don’t heavily block ribbing, cables, and other bumpy stitching.

The last, and, admittedly, the least of the benefits of blocking is that the project does become softer. It’s a noticeable, but not a huge difference.

Steam blocking is my preferred method of blocking acrylic; it’s quite easy if you have the materials (which, admittedly, may not be quite as easy to obtain if you don’t already own them). Here’s what you’ll need:

I block on an ironing board, which has unfortunately got a problem with its legs. So it's on the floor. Hooray!
I block on an ironing board, which has unfortunately got a problem with its legs. So it’s on the floor. Hooray!
  • An iron with a steam setting (there’ll be a place to store water in the iron, and a button to either emit steam in jets or to open or close off the steam flow; if yours doesn’t have these, it’s not a steam iron)
  • Blocking board, ironing board, or other heat-resistant surface
  • Pins (any kind you use for sewing is fine)
  • (optional) Towel
  1. Start by warming up your iron (hot enough for steam; there’ll usually be an indication, but if in doubt, crank it up to the highest setting (this is because water boils at above 100C, and the highest setting will ensure you’re over this threshold).

    Here's my steam iron. The green plastic houses a reservoir for the water, and the bottom on the top turns the steam output on or off. I keep a bit of distilled water in a water bottle for quick refills.
    Here’s my steam iron. The green plastic houses a reservoir for the water, and the button on the top turns the steam output on or off. I keep a bit of distilled water in a water bottle for quick refills.
  2. Go ahead and pin your project down to the blocking board or other surface. If you don’t have a blocking board or an ironing board with a cloth covering, you can pin it to a towel. If you’re looking to get extra length by stretching your project, stretch it now. Be careful when putting pins around the edges; use enough of them that you don’t have half
    moons straining to unstretch. Any shape that you pin the project down in will likely be the final, permanent state of it.
  3. Pick up the iron, and hold it over the project, suspending it in the air approximately 2 centimeters above the project. It’s important to get close enough to saturate the project with steam, but never to touch the iron to the project itself. That is the sole proprietor of killed acrylic, touching the plastic yarn itself with the hot iron. Start letting out the steam, moving the iron around to cover the entire project. Being careful not to steam your hand, you can periodically smooth the project, helping the pins with the stretching, and adjusting the shape of the project to make sure it comes out correctly. Don’t handle the pins too roughly; most pins will be a bit pliable under the very hot conditions.
  4. Hold the iron over the project, don't press it to it! The gap here could be lessened a bit, but it's tricky to do such photography while holding the iron.
    Hold the iron over the project, don’t press it to it! The gap here could be lessened a bit, but it’s tricky to do such photography while holding the iron.

    Continue steaming until you’re satisfied with the end product. In the case of stretching, it may take much longer to get the desired dimensions. Hopefully you will notice a much flatter, somewhat softer, and kind of “professional-looking” clean finish to your project.

Some other tips:

  • Don’t underestimate how much steam blocking makes your project lie flat. If you’re looking to block round objects such as hats or mittens, you can first fill them with stuffing (again ensuring you have the desired shape; it’s permanent!), and then block them.
  • Be careful to get your project moist, and even damp, but do not drench it. If you find it’s getting too wet, put a towel under the project in order to absorb some of the extra water.
  • If you, for whatever reason, have problems with the procedure described above, you can instead place a damp towel over your project and press the iron right to the towel.

Wet blocking is the other of the main options for blocking acrylic. Although admittedly much more basic, and in general, not as effective, it may provide more control over not harming complicated texture. You’ll need:

  • A spray bottle filled with water
  • (optional) A blocking board and pins
  1. For the most basic blocking, or perhaps for particularly delicate projects, go ahead and spray your project to a damp degree, and shape it with your hands. Get it quite wet, but don’t saturate it. You may have to watch it until it dries completely, to make sure any changes to dimensions are not reverted upon.
  2. The other option is to pin your project down to a board, once again watching the shape (and avoiding those annoying half-moons), and spray. After drying, the project should come off the board in the exact shape it was pinned.

For this post, I did an experiment in blocking. I made five more-or-less squares; two red ones in garter stitch, two yellow ones in stockinette stitch, and a brown one in moss stitch. All I did was knit them up, eyeball the squareness of them, and weave in the ends. Then, I blocked them. For each of these squares, there is a before photo (in which I’ve made it lie as flat as possible), possible intermediary photos, and an after photo.

Pre- blocking, as curly and uneven as they come off the needle.
Pre- blocking, as curly and uneven as they come off the needle.

Red Square One: This square was mostly in the correct dimensions, but the casting off was a bit tight, causing it to curl initially. By pinning it down and steam blocking it, I was able to get it to lie flat. It was also much softer afterwards.

Red Square Two: This square was initially shorter than it was wide, making it, well, not a square. From top to bottom, it measured 11cm. I decided to stretch this one as far as I could. After all the stretching I could get and a lot of steam blocking, the square was much more square-like, and measuring 13.5cm from top to bottom. The opacity of the square was quite obviously decreased, but not sacrificed. However, this could probably be fixed by a different selection of yarn weight and needle size. Lastly, this square did become softer.

Yellow Square One: At first, this square, made of the infamously curly stockinette stitch, would do nothing but roll into a sausage shape. After steam blocking, only the edges would not completely lie flat. The square will no longer roll into a sausage shape at any sort of prodding.

Yellow Square Two: Like the Yellow Square One, this square rolled up unforgivingly at first. I wet blocked this square to compare the flattening effects of the two types of blocking. Although it no longer aggressively rolls up, a larger border of this square (as compared to the Yellow Square One) still curls a quite a bit. The other immediately noticeable differences is that the wet blocked square is nearly the same thickness as off the needle, and not much difference in texture has occured. The steam blocked square is very flattened and much softer than the wet blocked one.

Brown Square: After subjecting the highly textured moss stitch to steam, the prominent bumps on the square were quite flattened. The texture is still there, it’s just nowhere near as bumpy as it was before blocking.

So after all the blocking, the difference in finished quality is very noticeable (the colors aren’t different; that’s just the lighting).

Before and after pictures. Ah, comparison.
Before and after pictures. Ah, comparison.

In all, what did I set out to demonstrate, and what did I learn from my blocking experiment? With the red squares, I did a simple finish with no special techniques, but the second one was stretched as far as it could go for extra dimensions. With the yellow squares, we can see how they evolve from rolly sausages to flat pieces, and we see that steam blocking is more effective in doing this than wet blocking. With the brown square, we confirm that texture is indeed flattened considerably by steam blocking.

Here are some resources to further advise you in blocking:

  • Here is a great video tutorial on blocking acrylic. Although it seems slow, it’s necessarily thorough and clear. The video creator also seems to be on hand to respond to any comment you make to the video.
  • Here is a tutorial for making your own blocking board from another blogger. I haven’t actually tested it out, but it looks like a cheap and feasible DIY project.

Although I only learned of the technique a couple months ago, once I learned I could do this to acrylic knitting, I’ve been blocking everything that needs it. I admittedly don’t have as much experience with wet blocking, but steam blocking is extremely fast and convenient, and I love the finished look it creates. Good luck with your endeavors in blocking.

(Yay for lighting changes and horrible camera quality.)

Yarn Over: Blocking Acrylic

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