Make it last
How to Unshrink a Sweater with Hair Conditioner
You cannot un-felt wool. You can sometimes relax a mildly tightened knit with conditioner, stretch, and block-dry. A child’s sweater stays a child’s sweater.
Updated 27 Aug 2026 · 6 min read · how to unshrink a sweater
Tightened versus felted
A Superwash crew that came out a size small still has visible stitch definition. Conditioner lubricates the fibers so you can ease them apart. A felted piece looks like boiled cloth: stitches gone, fabric denser, edges fused. That is irreversible without cutting it into something else.
The soak, the stretch, the block
Conditioner is a cationic slip, not a detergent. You are not cleaning; you are lubricating. After the soak, roll once in a towel, then lay the sweater on a dry towel on a table. Stretch a few centimetres at a time. Walk away. Come back. Pin to a blocking mat if you have one ($15–25) or weight the edges with books on plastic bags.
Hair conditioner beats baby shampoo for this job. A wool wash is for cleaning. Do not combine this with a hot rinse.
What not to try
Do not iron it bigger. Do not wear it wet to “stretch on the body” unless you like misshapen elbows. Do not put it back through a cotton cycle to “see.” Once you have a wearable size, wash it correctly forever.
Questions, answered
- Does this work on cotton or acrylic?
- Cotton that shrank in a dryer sometimes eases a little with wet stretch. Acrylic that melted or felted from heat usually does not. Wool is the use case.
- Which conditioner?
- The cheapest creamy one. Skip protein-heavy “repair” masks and skip anything with dye if the knit is pale.
- How much size can I get back?
- A little. A centimetre or two in the body if you are lucky. Not a full size on a boiled fisherman knit.
