Knitting guide
How to block knitting and crochet: wet, steam and spray methods
Updated by Khokhar Sab
To block knitting or crochet, dampen the finished piece, shape it to the measurements you want, pin it flat and leave it until it is completely dry. Wet blocking soaks the piece, spray blocking mists it after pinning, and steam blocking uses an iron or steamer held above the fabric. Check the yarn label first. Wool takes all three methods, while sources disagree about heat on acrylic.
What blocking does
Cocoknits describes blocking as wetting or steaming knitted pieces "to set the finished size and even out the stitches." Lion Brand puts it as stretching and shaping a finished piece to the proper size and shape. The same process works for crochet.
Handy Little Me lists what it fixes: uneven stitches, rumpled fabric, closed-up lace and creases. It also shapes a garment to the measurements in the pattern. Heart Hook Home adds cleaner edges and crisper stitch definition, especially in lightweight yarns.
Blocking has limits. Handy Little Me says it can't fix a wrong stitch count, a dropped stitch, wrong shaping, a sweater knit in the wrong size or a large gauge difference. It also won't stop stockinette from curling for good.
Blocking usually wears off. Heart Hook Home and Joy of Motion Crochet both say a piece may need blocking again after washing or long use. Heart Hook Home names one exception: acrylic set with heat.
The three blocking methods and which fibers suit each
This table sums up what Handy Little Me, Heart Hook Home, Joy of Motion Crochet, Simply Yarn and Lion Brand say about each method.
| Method | How it works | Fibers the sources suit it to | Watch out for |
|---|---|---|---|
| Wet blocking | Soak the piece, press out the water, pin it to size and let it dry | Wool and other animal fibers, cotton, linen, superwash wool | Hot water can felt wool. Cotton dries slowly. Superwash can stretch. |
| Spray blocking | Pin the dry piece to size, mist it with cool water and let it dry | Acrylic and synthetic blends, cotton, alpaca, delicate pieces | Gives the gentlest result, so it moves stitches less |
| Steam blocking | Hold a steam iron or steamer above the pinned piece, or steam through a damp cloth | Wool and cotton; sources split on acrylic | Never press the iron on the yarn. Heat changes acrylic for good. |
Can you block acrylic yarn?
Yes, but the sources disagree on heat. Lion Brand says acrylics are sensitive to heat and should not be steam blocked. Handy Little Me suggests spray blocking for acrylic and warns that steam risks permanent damage. Heart Hook Home takes the other side: acrylic needs heat for the block to last, so it prefers steam, knowing the change can't be undone. Joy of Motion Crochet allows heat with care, since too much breaks the fibers.
Simply Yarn adds that synthetics tend to spring back after blocking. If you want to try steam on acrylic, test it on a swatch first. For blends, Handy Little Me says to follow the care rules for the most delicate fiber in the mix.
What you need for blocking
- A flat surface you can pin into. Handy Little Me and Joy of Motion Crochet both list foam blocking mats with printed grid lines. Simply Yarn mentions children's foam play mats as a cheaper option. For a blanket too big for your mats, Handy Little Me uses towels on a carpeted floor or a sheet over a bed.
- Rust-proof pins. T-pins or blocking pins, so no rust marks the damp yarn. Heart Hook Home also lists knit blockers.
- Blocking wires. Long flexible rods that you thread through an edge to keep it straight. Handy Little Me uses them for lace and straight edges.
- Towels and a basin or a spray bottle, depending on the method.
- Wool wash or another gentle detergent for wet blocking.
- A tape measure and the pattern's finished measurements.
- A steam iron or garment steamer for steam blocking.
How to block knitting and crochet, step by step
These steps are for wet blocking, the method Cocoknits prefers and Handy Little Me uses for wool.
- Read the yarn label. Lion Brand, Handy Little Me and Heart Hook Home all start here. If the yarn can't go in water or near heat, the label says so.
- Weave in the ends. Handy Little Me says to weave them in first but wait to trim the tails until the piece is dry.
- Soak it. Fill a basin with cool or lukewarm water and a little wool wash, push the piece under and leave it 15 to 20 minutes, per Handy Little Me. Joy of Motion Crochet allows up to 30 minutes. Avoid hot water on wool, which can felt it.
- Press out the water. Squeeze gently and never wring or twist. Then lay the piece on a towel, roll it up and press to soak up more water.
- Lay it out and pin. Cocoknits pins the center top and center bottom first to set the length, then the width. Measure as you go and match the pattern's finished sizes.
- Let it dry completely. Handy Little Me gives 4 to 8 hours for lightweight pieces and 24 to 48 hours for thick wool sweaters and blankets. Cocoknits says 12 to 24 hours in a warm room with a fan, and up to a week in damp weather.
Handy Little Me also suggests checking for dye bleeding when a piece mixes dark and light colors. A swatch in water shows it before the whole project goes in.
How to spray block
Lay the dry piece on the mat, shape it and pin the edges. Mist it with cool water until damp, not soaked, then leave it pinned until dry. Handy Little Me calls this the gentlest method.
How to steam block
Pin the piece to size first. Lion Brand lays a damp washcloth over the item and steams through it with an iron, shaping as it goes. Handy Little Me holds the iron or steamer just above the fabric instead and keeps it moving. Cocoknits uses the iron's lowest heat with a wet cloth and no pressure. In every version the hot iron never sits on the yarn. Heart Hook Home prefers steam because the piece dries much faster.
Blocking lace
Joy of Motion Crochet says blocking makes lace stitches easier to see. Handy Little Me says wet blocking gives the most dramatic result, with pins for points and curves and blocking wires for straight edges. Simply Yarn gives the same split: thread wires through straight edges and use T-pins to pull out a scalloped edge into points. It soaks the lace for at least 15 minutes first.
Simply Yarn recommends natural fibers such as wool, alpaca, cotton and silk for lace, because synthetics tend to spring back after you unpin them. As with any blocked piece, leave lace pinned until it is completely dry.
Blocking granny squares, sweater pieces and blankets
Heart Hook Home blocks identical pieces such as granny squares before putting them together, so every square ends up the same size. Pin each square to the same measurement on a gridded mat. Once they match, the guide to joining granny squares covers the seams and joining order. The granny square calculator works out how many squares a blanket needs.
For sweaters, Handy Little Me blocks each piece before seaming so the front and back match. Cocoknits says the seams may need a little steam after you sew them. A large blanket can go on towels on the floor.
Not everything needs blocking. Joy of Motion Crochet gives stuffed amigurumi toys as one example.
Why you block your gauge swatch before measuring
A swatch can grow or shrink in water, and the finished piece will do the same. Handy Little Me uses the swatch to test a blocking method before trying it on a whole project, to see shrinkage, growth and color release. Heart Hook Home also tests on a swatch first. So treat the swatch the way you will treat the finished piece, then measure it. The guide to measuring gauge covers swatch size and counting.
Here is what happens if you skip that step. Say a pattern asks for 20 stitches per 4 inches and your unblocked swatch matches it exactly. You cast on 200 stitches for a 40 inch sweater body, or 250 for a 50 inch blanket. Then blocking makes the fabric grow. The knitting gauge calculator works out the result:
| Growth after blocking | Blocked gauge (sts per 4 in) | 200 st sweater body | 250 st blanket | Cast on instead for the sweater |
|---|---|---|---|---|
| None | 20 | 40 in | 50 in | 200 sts |
| 2% | 19.6 | 40.8 in (+0.8) | 51 in (+1) | 196 sts |
| 5% | 19 | 42 in (+2) | 52.5 in (+2.5) | 190 sts |
| 10% | 18.2 | 44 in (+4) | 55 in (+5) | 182 sts |
A 2% change is less than half a stitch over 4 inches, small enough to miss when counting. Yet it adds 0.8 inch to the sweater. At 5% the body comes out 2 inches bigger around. At 10% the sweater gains 4 inches and the blanket 5. Shrinkage works the same way in reverse.
The last column shows the fix: measure the blocked swatch and cast on for that gauge. At 10% growth, 182 stitches give the 40 inch body the pattern intended. The gauge calculator does this for any pattern count. To see how a few inches change the fit, read knitting ease explained. The sweater calculator works out the stitch counts for a whole sweater from your blocked gauge.
Common questions
Do you have to block crochet and knitting?
No, but Joy of Motion Crochet recommends it for swatches, granny squares, lace, blankets, sweaters and shawls. Joy of Motion Crochet says stuffed amigurumi don't need it.
How long does blocking take?
The soak takes 15 to 30 minutes. Drying takes from a few hours for a small spray-blocked piece to 48 hours for a thick sweater, per Handy Little Me. Steam dries fastest.
Can blocking make a sweater bigger?
A little. Blocking can pull a piece to the pattern's measurements, but Handy Little Me says it can't fix a sweater knit in the wrong size or a large gauge difference.
What if a piece blocks too big?
Cocoknits says you can block it again. Wet it and pin it to the smaller size.
Is blocking permanent?
Usually not. Heart Hook Home and Joy of Motion Crochet say pieces may need blocking again after washing, except acrylic that has been set with heat.
Sources and further reading
Handy Little Me covers every method, fiber, drying times and what blocking can't fix in Blocking Knits: How To Block Knitting Step By Step. Heart Hook Home explains steam, wet and spray blocking for crochet and acrylic in How to Block Crochet. Simply Yarn compares methods for stockinette, lace and cables in How to block knitting projects. Lion Brand gives its steam and wet methods and its acrylic warning in What is blocking, and how do I do it? Cocoknits shows pinning order and drying in How to Block Your Knitting. Joy of Motion Crochet also publishes a detailed guide to the three methods.
Video tutorial
"How to Block Crochet - 3 DIFFERENT METHODS!" by Hooked by Robin, on YouTube. The video loads only when you press play.