Blocking knitting: wet, steam and spray, explained

Blocking is the finishing step where you wet or steam a finished piece of knitting and shape it to its final measurements as it dries. It evens out the stitches, sets the fabric and opens up lace. There are three methods: wet, steam and spray. Which one to use depends mostly on the fibre.

What blocking does and does not do

Blocking does the following: evens out uneven stitches, sets the final dimensions, blooms the fibre (wool softens and fills out), opens lace patterns, and lets you match pieces to the same size before seaming.

Blocking does not fix a wrong gauge or rescue a garment knitted the wrong size. Blocking is shaping, not stretching. It does not permanently cure stockinette curl. It reduces it, but the curl comes back. It does not last forever either. Re-block after every wash. From then on, it is simply how the garment is dried.

Wet blocking (the standard method for wool and animal fibres)

This is the full method, and it is essential for lace.

1. Fill a basin with cool to lukewarm water, never hot, and a splash of wool wash. No-rinse types are easiest.
2. Submerge the piece and press out the air bubbles. Do not agitate or rub. Animal fibres can felt.
3. Soak for 15 to 30 minutes, until fully saturated.
4. Lift it out supporting the whole weight with both hands. A soaked knit lifted by one edge stretches permanently.
5. Squeeze gently. Never wring or twist.
6. Roll the piece in a towel and press firmly, taking it from wet to damp.
7. Lay it flat on blocking mats and shape to the pattern's finished measurements, using a tape measure. Pin with rust-proof T-pins. Always pin lace, using plenty of pins, or use blocking wires to avoid scalloped edges.
8. Leave until completely dry (24 to 48 hours), then unpin.

Steam blocking (quick evening out, and the acrylic option)

Pin the dry piece to measurements. Hold a steamer or steam iron above the fabric without touching it, and let the steam penetrate in a few passes. Let it cool and dry before unpinning. This is the quick way to even out stitches, and the only method that has much effect on acrylic.

Acrylic warning. Direct heat on acrylic melts the stitches into place. Knitters call this "killing" the fabric, and it is irreversible. It removes the bounce and drape permanently. Steam acrylic only from a distance and never touch it with the iron.

Spray blocking (the gentle option)

Pin the dry piece to shape, spray with cool water until damp, and leave to dry. This suits delicate pieces and quick refreshes. It also suits superwash wool, which behaves badly when fully soaked: superwash relaxes and can grow by inches in a wet block. Spray blocking keeps it under control.

Which method for which fibre

Fibre	Method
Wool and animal fibres	Wet block (the full method)
Lace, any animal fibre	Wet block with pins or wires, always
Superwash wool	Spray block (soaking makes it grow)
Acrylic	Steam from a distance, with care
Cotton and plant fibres	Wet or spray. The "memory" is weaker, so results fade faster

Common mistakes

• Hot water, wringing or agitation. These cause felting and permanent stretch.
• Lifting a soaked piece by one edge. Support the whole weight.
• Stretching ribbing. Ribbing usually should not be stretched at all, or it loses its spring.
• Too few pins on lace. This gives spiky, scalloped edges. Use more pins, or wires.
• Unpinning early. Damp fabric loses the blocked shape. Wait until it is fully dry.
• Touching acrylic with the iron. This is irreversible.