Blocking & Finishing

The Craft / Blocking

Blocking is the act of wetting or steaming a knitted or crocheted piece and then shaping it while it's pliable, allowing it to dry in the shape you want. The result, when it's done correctly, is the difference between a garment that looks like a craft project and one that looks like it was made by someone who knew what they were doing.

Most knitters learn blocking either very early (if they had a patient teacher) or after they've been knitting for years without realizing what they were missing. The frustrating thing about blocking is that until you've seen the before and after on the same piece, it's hard to understand why it matters. Lace in particular is nearly incomprehensible before blocking and fully itself afterward: the fabric opens up, the pattern becomes visible, the geometry resolves.

What Blocking Does

When wool or protein fiber gets wet, the hydrogen bonds in the fiber structure relax. The fiber becomes pliable, willing to take a new shape. As it dries, those bonds re-form in the new configuration. The result is a piece that holds the blocked shape until it gets wet again.

This is also why wool garments can stretch if they're washed and laid flat to dry without being shaped, and why knitted woolens should generally be reshaped while wet rather than left to their own devices. The same property that allows blocking works against you if you don't use it deliberately.

Blocking serves several specific purposes in a finished piece: it evens out stitch size and tension inconsistencies, opens up lace motifs that are otherwise compressed, softens the hand of the fabric, and sets the final measurements of a garment. A sweater that comes off the needles several centimeters smaller than the schematic calls for will often reach the right dimensions after blocking.

Methods

Wet blocking is the most thorough and most widely applicable method. Soak the piece in cool water (with or without wool wash) for at least 20 minutes, until it's saturated throughout. Then press out the water without wringing, roll the piece in a clean towel and press firmly to remove more water, and lay or pin it flat to dry in the desired shape.

The amount of shaping you can do while wet depends on the fiber. Wool stretches and pins readily; silk drapes more than it stretches; plant fibers behave more like fabric and less like knitting. Non-superwash merino will block out the most dramatically. Superwash merino will also block well but tends to relax and grow more than non-superwash, so account for that when pinning.

Steam blocking applies steam from an iron or a dedicated steamer to the dry knitted piece without submerging it. Hold the steam source above the fabric (don't press down on it) and allow the steam to penetrate. Then shape by hand and allow to cool and set. Steam is faster than wet blocking and works well for acrylic and acrylic blends that don't respond to water, but is generally less effective on all-wool pieces than wet blocking.

Spray blocking is a light version of wet blocking: spray the piece with a water bottle until damp, then pin to shape and allow to dry. It's useful for gentle shaping when you don't want to fully saturate the fiber, and appropriate for pieces that are mostly there and just need light coaxing.

Tools Worth Having

Blocking mats are the foundation of the process. Foam puzzle mats designed for blocking provide a surface you can pin into, and they're large enough to block most shawls and garments. A single small mat is often not enough; it's worth having several interlocked mats or a large dedicated blocking surface.

Blocking pins need to be rust-resistant. Standard straight pins will rust on wet fiber and leave rust stains. Purpose-made blocking pins or stainless steel T-pins (available from sewing or knitting suppliers) are the appropriate tool. You'll need more than you think; a large shawl might take 50 or more pins.

Blocking wires thread through the edge stitches of shawls and lace pieces and allow you to block a long straight edge with two or three pins per wire rather than pinning every stitch. They're not essential, but they're faster, and they produce straighter edges than pinning by hand.

A measuring tape for verifying that the blocked dimensions match the pattern schematic.

Notes on Lace

Lace blocking is one of the more dramatic transformations in textile work. Unblocked lace looks crumpled, the pattern compressed and nearly invisible under the tension of the unrelaxed stitches. Blocking opens the yarn-overs, stretches the fabric into the geometry the designer intended, and makes the pattern legible. If you have lace on your needles that seems dull and incomprehensible, this is probably why: wait until after blocking to judge it.

When blocking lace, pins the points and scallops of the edge out aggressively. The pattern was designed for the blocked dimensions, not the unblocked ones, and a lace shawl pinned to exactly the schematic measurements will show the full intended geometry. Block wires along the top edge keep the edge straight while you can direct your attention to pinning the pattern points.

Notes on Silk and High-Twist Yarns

Silk wet-blocks to a drape and a softness that is noticeably different from the stiff silk that came off the needles. Wet silk stretches easily and recovers less than wool; be careful not to overblock and distort the piece. The fabric should be supported while wet, not allowed to hang.

High-twist yarns, those with a springy, energetic twist that wants to bias on the needles, often relax considerably in blocking. The biasing that made the fabric look crooked on the needles may disappear entirely. If you're working with a yarn that's showing pronounced biasing, finish the piece before worrying about it.

Notes on Non-Wool Fibers

Plant fibers (cotton, linen) and blended yarns with significant synthetic content block differently than wool. Cotton responds to blocking but doesn't set in the same way; it will return to a relaxed state when washed and need re-blocking. Linen relaxes slightly with wet blocking and may soften a little, but its structural stiffness doesn't transform the way wool does.

Acrylic responds to steam but doesn't wet-block in any meaningful way. If you have a piece that contains a significant percentage of acrylic and it seems wrong in some way, steam it; if the steam doesn't help, you may be working with a fiber that simply won't change shape with standard blocking methods.

Continue reading: Working with Hand-Dyed Yarn · Fiber & Its Properties · The Dye Pot