How to block knitting

A handy little guide to blocking knitting projects – no matter if it’s a scarf, a sweater, or socks

Do you want to know the most important factor that sets those charmingly self-made projects apart from those that look like unique handmade masterpieces? What sets the beginner apart from the experienced knitter? One word: blocking! In knitting, there’s no other simple finishing technique that will make such a difference, prevent curling, and lead to an overall nicer stitch definition.

In this tutorial, I want to show you how to block knitting – no matter which project you are working on and which fiber you are using. Blocking is a concept that can be applied to almost all patterns. All in all, it’s a pretty simple and straightforward process any beginner will easily be able to implement. You only have to keep some simple little details in mind. So make sure to read all the way to the end!

What is blocking?

a knitted project before and after blocking
The same swatch before and after blocking

Animal fibers/yarn is nothing but thousands of hairs spun together into a thread. At a microscopic level, each of these hairs is made out of thousands of strands of keratin bundled together. These keratin strands are held together by strong disulfide bonds (can be broken with a perm) and weaker hydrogen bonds. Whenever hair gets wet, these bonds break making the hair a bit more malleable. And as it dries, new hydrogen bonds will be formed.

That’s the basic principle behind any hair curler and that’s how blocking works in knitting. You make a project wet, it becomes a bit more malleable, and then pin it into the desired shape, and as it dries, the newly formed hydrogen bonds will ensure that it will keep the shape (until it gets wet again).

Important: This is the reason why wet blocking will only work on keratin-based fibers. So, anything shorn/obtained from animals. This means sheep wool, yak, alpaca, cashmere, vicuna, qiviut, possum, etc. For further options, see below.

Note: I earn a small commission for purchases made through links in this article.

Instructions: How to block knitting

a knitted project after blocking resting on a blocking mat

Blocking can be done in any state of your project but most knitters will do it once they've bound off all stitches and wove in the tails. For seamed projects (like a sweater) it is sometimes preferable to block the individual pieces to ensure they are all of the exact same size and your seams end up nice and neat.

Active Time 15 minutes
Additional Time 1 day
Total Time 1 day 15 minutes

Materials

  • (Optional) mild soap or wool detergent

Instructions

Before you start: Verify this process using your gauge swatch. If you are a beginner, go through all the steps below using a swatch to get a good feel for the yarn and to ensure it works the way you intend it to work.

  1. Soak your finished project in lukewarm water (never hot!) in your sink, bath tub, or a small bucket. Consider adding mild soap or a wool detergent. This will help to remove any spinning oils, residual dyes, or debris still locked in the fiber.

    soaking the project in lukewarm water

    Important: Make sure to read the label of your yarn before you soak your project to ensure that whatever treatment you apply is suitable for this fiber.
  2. Let the project soak for around 30 minutes. Avoid intense stirring, any form of rubbing, or over-stretching. In this suspended state, you can, however, gently stretch your project a bit in all directions to let those stitches balance themselves out.

    someone stretching out the submerged project gently in all directions

    Important: Untreated animal hairs are covered with microscopic little scales. Water will let these rise up. If you rub hairs against each other in this state, the scales will interlock and you will create felt. This process is facilitated by heat. So best avoid both.
  3. Drain the water and rinse your project using cold water. Again, avoid any sort of rubbing and be gentle.

    rinsing the project after soaking with cold water

    Important: Avoid any stark temperature contrasts. This, too, can lead to felting. Since you've only used lukewarm water, to begin with, the water will probably have cooled down to room temperature in the past 30 minutes anyway. So, this should be no problem.
  4. Gently press your project to remove the excess moisture without ever wringing it out or rubbing it. Instead, fold your project together a bit and press down gently with your hands. Always just go in one direction and continue gently until your project stops dripping.

    gently pressing out the excess water with the hands

    Important: Your wet project will be very heavy. Always support the full weight with both hands and never pick it up just on one edge/tip to avoid stretching single stitches or seams out.
  5. Place your project on a clean towel. Again, support the full weight with both hands as you do so.

    transferring the project to a towel while supporting the full weight with all hands.
  6. Create a nice and tight little roll with your project nestled on the inside. A bit like a jelly or cream roll.

    creating a nice towel roll with the project nestled inside
  7. Gently press on the roll you've created in this manner using your hands. If it's a big project, you can also put the towel/project roll on the ground and apply pressure with your feet. Again, no rolling or rubbing. Just let the towel wick away most of the moisture still locked in the fabric.

    gently pressing the towel roll without rubbing to get rid of the water

    The project should be almost dry to the touch at the end of this process. If it still feels wet, use another dry towel and repeat.

    Note: There will still be more than enough moisture locked inside the hairs for the blocking process to work. Your project will, however, be lighter (= easier to handle) and will also dry faster.
  8. Transfer your project to a blocking mat (again, support the full weight of your project to avoid stretching out individual stitches or seams). If you don't own one and you don't want to buy one, you can also use a towel on your carpet/ironing board/mattress, or any other clean and soft surface that you don't mind getting wet and you won't need for the next 24 hours.

    transferring the project to a blocking mat carefully
  9. Roughly pin your project into the desired shape using only a couple of (rust-free!) pins. This first pass will only be a rough sketch of the final shape.

    roughly pinning the project into shape using rust free steel pins
  10. Next, using a lot more pins, try to approximate your ideal shape. Stretch out the fabric a little bit (without over-stretching; this often is irreversible!) and try to obtain a shape and stitch definition YOU are satisfied with - one little pin at a time.

    adding more pins to the project and -readjusting others the get the project into the perfect shape

    If you've knitted a fitted garment, consider verifying the size using a tape measure and compare things with the measurements in the pattern (or a similar item in your wardrobe).

    Important: It's called blocking not "stretching until you can stretch no more". The fabric absolutely does not need to be under tension. Whatever you see on the blocking mat should be what you want to see when you wear it. The fabric will keep the shape you pin - no matter if it's taught or not.
  11. Then, take a step back and take another look at the shape you will be blocking your project into. Make sure that all lines are straight, and especially make sure that you spaced your pins in a way that you don't end up with a spiked edge (except you want that or your pattern calls for it. E.g. a picot bind-off).

    a project where too few pins were added. spikes are the result

    You can combat these spikes by adding even more pins. There are special blocking combs and blocking wires that make it a little bit easier and faster to obtain straight lines.

    Also, try to avoid splitting the yarn with the pins or stretching out single loops. This, too, can result in slightly wonky stitches around the edges. I typically place my pins one or two rows further in to avoid these kinds of problems.

    If it's a large project you want to block, make sure that the fabric in the middle doesn't have a visible slant/bias and the columns align neatly. If they don't, try to straighten things out by gliding across with your hands.

    adding pins in the middle of a project to block all portions evenly

    You can also add more pins in the center of your project to lock certain portions into place. This can be very helpful if you've knitted a project with various different knitting stitch patterns (different stitch patterns typically have a slightly different gauge and may contract a bit more or less).
  12. Once you are satisfied, let your project dry flat. Depending on how much moisture was still stored in the fabric after the little towel trick, the room temperature, and the general ventilation, this typically takes around 24 - 48 hours.

    letting the project dry flat with the pins keeping things in shape

    Note: Some yarns and dyes might bleach out when exposed to direct sunlight for too long. That's why I personally never try to speed things up putting my blocking mats into the sun.
  13. Once your project is completely dry (important!), simply remove the pins and wear it with pride.

    the swatch after having removed the pins - it remains square without any curling

Notes

Every time you wash your projects, you may have to repeat this process. Ambient moisture may also let your edges curl in overtime or create visible creases if stored for a longer time.

Since most animal hair will slightly felt when you wear your garment and the stitches will thus lose quite a bit of their freedom of movement, the first blocking is the most important one.

You will also notice that, once you've over-stretched a project, it will not simply bounce back after a thorough wash. That's why it's very important to avoid that. For this very reason, hems, cuffs, and any sort of ribbings might not need to be blocked at all.

Blocking projects knit in the round

The basic blocking process described above works for every project knitted with animal fibers. Tubular projects have, however, no edges. When you simply stretch these out on your blocking mat and let things dry, you typically end up with permanent and quite visible fold lines. To avoid that you have several options:

#1 Sock blocking boards

special sock blocking boards used to make socks neater on a wooden table

One of the most popular patterns to knit in the round is certainly socks. And they are also one of the easiest to block since there are special sock blocking boards. You will find a broad range on Etsy or on Amazon (and of course in any good local yarn shop).

These are basically just slabs of wood (or metal) in the shape of a foot. Instead of pins, you can simply slip them on after washing and let them dry. The only problem is that you typically need one for each size. There are some adjustable ones but they typically just let you adjust the length and not the width of your instep.

If you only knit for yourself and your loved ones, you typically don’t need that many. I, for example, have one for myself and one for my partner (who happens to have the same size as my dad). Since they are flat, it’s rather easy to store.

#2 Caulking backer rods

using filler rope to block a hat to avoid fold lines
Getting ready to block a head using backer rods

For all other projects, I use backer rods. These are just thin little foam cords used for caulking but I use them to block my knitting (you can buy them on Amazon or at your local hardware shop). I simply insert them into the “edges” of my tubular projects and block around them.

You can easily pierce them with your pins. The rest remains the same and it easily gets rid of the fold lines. And the good part: you can use them for any tubular project – no matter the shape or the size. Perfect for sweaters (click here to see how to knit a sweater)!

Just make sure to get backer rods (they also go by the name filler rope) that are reasonably thin enough. Except you are working with super chunky yarn, 1/4″ is plenty!

#3 Balloons

using a pink balloon to block a hat so there will be no fold lines

If you are knitting a hat (like my plain vanilla ribbed beanie), you can also use a balloon to block your finished project. Simply inflate it until it’s roughly the size of your head, put it on and let things dry. In my experience, longer balloons are preferable as it will allow you to accommodate the (unfolded) brim.

I have also seen people using wooden or foam millinery head blocks. I would personally say that it is less than ideal. They are, after all, typically not adjustable and typically designed for a special hat form that is decidedly not a knitted beanie. Still, if you happen to have one around, why not.

Steam blocking

Wet blocking, also called immersion blocking, does little for artificial fibers (such as nylon, acrylic, etc). Simply, because these are not held together by (hydrogen) bonds that can be broken with water or soap. But even if your yarn reacts in water, using a steamer to block your knitting can be advantageous for multiple reasons (see below).

Here’s how steam block knitting:

Step 1: Pin the dry project to your blocking mat (the way I showed you above).

Step 2: Use a steamer (here is a selection of steamers on Amazon) and go across it a couple of times without touching the fabric. Try to get one with a tank as large as possible. You want to saturate the fabric with moisture and not only get rid of creases in your shirt or curtains.

blocking a swatch knitted with cotton yarn with hot steam

Step 3: Let the project cool off completely and then wait a couple of hours until all moisture has evaporated. Since the water was hot, to begin with, this typically is a lot faster than wet blocking.

Step 4: Remove the pins and wear your project with pride.

Steam is, if you will, the blocking superpower. It will work for almost all projects and fibers. Alongside the obvious water vapor, it also introduces heat (without adding friction). Here is a little breakdown of how it works for each fiber:

Nylon, Acrylic

Most artificial fibers, such as nylon or acrylic, are inflammable. Heat them too much, and they will melt. By going over your project knitted with acrylic yarn with steam, you are basically melting the stitches into place. This is typically a non-reversible process.

That’s why it’s important to use medium heat and keep a little distance from the fabric. Definitely test things out with a swatch first, You don’t want to end up with plastic slag. The vapor itself does little to nothing. It’s just the conduit for the heat.

Cotton, linen, hemp, etc

Most plant-based fibers can be wet-blocked. No matter if it’s cotton, linen, or hemp. After all, they all end up crinkled after washing and you need to iron them. However, a lot of these fibers also can soak up a lot much moisture. This risks stretching out stitches too much while washing and pinning things into shape.

In addition, most of these plant-based fibers are also susceptible to heat and you can use that to your advantage when blocking. So, by steam blocking your cotton knits, you avoid stretching them out and the heat helps to fix the shape.

Important: Especially cotton can shrink up to 20% under the influence of heat. So, this is another thing you might want to test out on your swatch. It pretty much depends on whether the yarn has been pre-shrinked or not. But if it hasn’t, then things might get tricky as this might also happen when you wash your garment the next time. So maybe factor that in from the start.

Wool, Alpaca, Cashmere

Normally, you want to avoid heating any animal fibers. After all, heat will let those scales covering each hair rise and this risks felting. But if you pin the dry projects into place and then apply the steam, there is no risk since you don’t have to move or rub the fabric at all.

The heat, of course, will typically have no lasting long-term influence on sheep wool or alpaca yarn – at least not if you only do it once. Of course you absolutely have to wait until the fabric entirely cooled down before you even think of removing any of the pins.

The steam, however, will have the very same effect as the water bath. It will break the hydrogen bonds and facilitate the formation of new bonds. There are three noteworthy differences.

  1. Steam-blocking protein-based fibers will be faster. It might take less than an hour for things to dry and cool down.
  2. Especially fuzzy fibers and some novelty yarn can drastically change its appearance when wet. They can also be a lot easier to felt and pill – even if you are careful. By steam blocking them, you might be able to achieve a much neater result.
  3. On the negative side, the immersion in water allows you to gently stretch the fabric out in this suspended state. This process can help to further improve the stitch definition (for example, of a nice superwash merino yarn or so).

Ironing

Under normal circumstances, ironing your knitwear is something you absolutely want to avoid. It will flatten the stitches (often permanently) and the fabric will lose its fluffy appearance and feel. But as always, there are caveats.

Linen

Linen yarns can often have a somewhat rustic/more irregular stitch definition. Some people thus prefer to gently iron their linen summer knits to achieve a more uniform stitch definition. Often, the fabric also will acquire a nice little sheen.

On top of that, linen is typically a bit more on the stiffer side. By maltreating it a bit, you let those fibers loosen up (essentially you are breaking it down even more). If you own linen cloths/shirts/trousers, you might have observed that they actually end up softer, the more often you wash them.

Important: This is, of course, something you might want to test on a swatch before you commit!

Stranded knitting projects

blocking a fair isle project by ironing it under a damp towel on a table

Most forms of stranded knitting create floats on the backside. This introduces irregularities into your fabric. To put it quite bluntly, a Fair Isle sweater sometimes looks a little bit more on the wonky side and not fair and smooth the way your average stockinette stitch project appears (although it is also just knit stitches on the right side).

You can combat that by gently ironing your finished project. Most knitters will typically place a damp towel on the finished project and then iron across it without ever touching the actual fabric.

This does two things: The towel dampens the flattening effect a bit and the indirect steam will, of course, help to block things into shape (although heat alone, can already break the hydrogen bonds. That’s how a flat iron works, after all)

This is another alternative you should definitely test out using a swatch. The fabric will end up having a distinctly different look and feel. Some people love the appearance of smoothness, while others miss the springy texture of their knitting. Although it has to be said that stranded knitting is typically more on the rigid side, to begin with.

However, you won’t be able to work with pins. So, this method only works with patterns where the shaping is already in the knitting. For a lace project, it’s probably an ill choice. And you probably don’t want to flatten your cables either.

Misting

someone using a vapour dispenser to mist a knitted projects to block it

If you don’t have a steam or an iron. You can also pin your dry project into shape and then use a mist bottle with clean water and thoroughly mist the piece. Once dry, you can remove the pins and your project will also retain it’s shape.

This method works similarly to steam blocking without introducing heat. For some fibers, this can be advantageous. You also don’t need any expensive gadgets either. At the same time, it’s a bit hard to saturate the full fabric. As a result, it might not give you the same consistent results. But it sure is the least invasive method.

Anyway, That’s how to block knitting. Make sure to comment below if you still have any questions.

how to block knitting for beginners

16 thoughts on “How to block knitting”

  1. I’ve been blocking woolens for a long time (like 60 years) My Mom taught me how to wash wool sweaters long before I learned to knit. And since knitting I’ve learned more about the process for other fibers as well.

    I just want to say this is a really well done, very thorough tutorial. I also appreciate that you explain why things work, as well as how to do it.

    Thank you!

    Reply
  2. Always informative and well-presented! I am presently making 3.75 inch blocks with garter stitch using a cotton fingering weight with a strand of kid silk; ultimately all the various small blocks get seamed into a cardigan. It’s going to be a LOT of seaming, but it’s also going to require A LOT of blocking too! Your blog post was extremely timely—Thank you!

    Reply
  3. Norman, this is such an interesting and informative article. Much of this I have learned over 41 years of knitting, but it never hurts to refresh my memory. I rarely knit with synthetic* fibers so it’s good to have this resource if I ever do. What I really liked is the science behind what happens to the “hair” fibers. Sure, I knew about the scales locking together under heat and friction (felting), but to learn about the disulfide and hydrogen bonds holding all the fibers together and weaking when wet was completely new. High school and college chemistry classes didn’t discuss fibers.

    So, thank you for this invaluable information.

    *I admit to being a natural fiber snob in all things knitting or sewing.

    Reply
  4. Hi, Norman! As usual, your tutorial on blocking is concise, complete, and valuable. Well, except I wish you would discuss blocking silk. I love knitting with and wearing silk, it’s so kind to my skin, especially my hands. I usually wet block it with decent results, but it doesn’t hold its shape. That’s not usually a problem because the project is supposed to be drapey, but sometimes I wish the edges wouldn’t curl. Any suggestions? Thanks for all the wonderful information you give us knitters!

    Reply
  5. hi norm,
    even though i already know how to block knitting, i found this tutorial very interesting, comprehensive, and completely accurate!
    thank you very much for taking the time to create it and share with the knitting community,
    best regards,
    margaret lerner 🙂

    Reply
  6. Thanks for such an in-depth description for blocking, Norman. All of the techniques you described reminded me of how my dad always washed his own shelby cap and blocked it with a dinner plate. You could do the same for a knitted beret. Just sayin’

    Reply
  7. For soaking wool, I actually prefer hair shampoo. It usually is a very gentle wool wash, and quite likely to be in the household anyhow.

    Also for wool, I have a little splash of white vinegar in the last rinse because that gets rid of the suds, and restores the pH wool likes.

    Reply
  8. Thank you for this informative post. I just have one question about blocking a chunky wool knit sweater (ribbed cuffs) in the round. How would you avoid the permanent creases you mentioned? Is it better to not block an item like this?

    Reply
  9. Wow – I don’t know how I missed this one. It’s the best and most complete description I have seen yet! THANK YOU! ❤️

    Reply

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