Blocking knitted fabric

A piece straight off the needles is rarely its final size. Stitches are uneven, lace is a crumpled mass, edges roll and the measurements are a few centimetres off. Blocking is the step that sets all of that: the knitting is wetted or steamed, shaped to the measurements in the pattern, and left to dry. It is the difference between a piece that looks homemade and one that looks finished.

What happens to the fibre

Wet wool, hair fibres such as alpaca and mohair, and silk relax. The individual fibres loosen their bonds, the stitches settle into place and the fabric can be moved to a new shape. When it dries, the fibres lock in the position they are in. This is why wet blocking can stretch a lace shawl to twice its unblocked width and have it stay open for years.

Plant fibres, such as cotton, linen and bamboo, respond differently. They relax while wet but do not hold a shape as strongly and often return to the old size if wetted again. Acrylic has no real memory; heat can permanently change it, but wet blocking has little effect.

Wet blocking

The fullest effect comes from soaking.

1. Fill a basin with cool or lukewarm water. Add a wool wash if you want, though plain water is enough.
2. Submerge the piece and press it down until it sinks. Leave it for 15 to 20 minutes.
3. Lift the piece out without wringing or twisting. Squeeze it gently and lay it in a dry towel, roll it up, and press it to remove most of the water.
4. Lay the piece on a flat blocking surface, such as foam tiles, a mattress covered with a towel, or a dedicated board.
5. Shape it to the measurements in the pattern. Use a tape measure to check width and length. Pin the edges, or thread blocking wires through the edge stitches for long straight lines.
6. Leave it to dry completely. A sweater can take a day or two.

Spray blocking

Pin the dry piece to the shape, then spray it with water until it is damp all the way through. Leave to dry. It is faster than soaking, good for small items and for finished garments that only need a bit of straightening, and it works well on separate pieces that will be sewn up.

Steam blocking

Hold a steam iron 1 to 2 cm above the fabric, never pressing on it, and let the steam penetrate. Pin the piece first, then steam, then let it cool in place. Steam works on acrylic, which it can permanently relax, so a test swatch is useful before doing the whole piece. Flat pressing with an iron can flatten the texture of ribs, cables and lace and should be avoided on those.

What blocking can fix

• Uneven stitches. The wetted fibres even out and the fabric looks smoother.
• Curling edges. Stockinette rolls at the edges; pinning it flat and drying it reduces the roll, though it may return partially. A border of garter stitch or rib is the permanent fix.
• Lace. Pulled open and pinned at each point of the edge, the pattern appears.
• Size. A piece that is 2 or 3 cm too narrow can be stretched; a piece that is too big can be shaped smaller only a little.
• Seams. Blocking pieces before sewing makes them easier to match.

What it cannot fix

It will not correct a count that is wrong by a large amount, a gauge that is far off or a piece made from yarn with no memory. Measurements from your swatch should be checked before the garment is knit. A swatch that has been blocked gives the true gauge, and stitches per 10 cm after blocking are the numbers to use. The needle database can help you pick the next size up or down, and the hat designer in the tools section uses your gauge to compute the cast on.

Cables and texture

Cables and raised stitches need a light touch. Stretching them flat loses the relief. Shape to measurements only, and let the piece dry without pulling. Laying a dry towel over the piece and pressing gently, rather than pinning tightly, leaves the texture intact.

Colourwork

Stranded colourwork evens out strongly in a soak. The floats settle, the colours lie side by side neatly, and puckered areas relax. Pin to the size of the pattern but avoid heavy stretching, since the floats have a fixed length.

A quick reference

Drying time

Flat, away from direct heat, with air moving around the piece. Turn it over when the top is dry, so the underside finishes. Unpin only when the fabric is dry to the touch in the thickest parts, such as the seams and the edges.