Washing wool: the theory
why temperature, detergent and spinning behave differently than with cotton
Wool doesn't need to scare you. You just have to stick to a few numbers: water temperature, detergent pH and spin speed. Below we break safe wool washing down into its basics, step by step.
Wool isn't "untouchable". That's a myth that stops many people from washing at home things that would easily survive it. You just need to stick to a few concrete numerical limits to stop washing from being a gamble.
Four variables determine the outcome: water temperature, detergent choice, contact time between fabric and water, and how it's spun. Each one alone seems minor. Together, though, they make the difference between a sweater that survives dozens of washes and one that shrinks the first time.
Three numbers you need to know before washing
Temperature and contact time
Maximum 30°C, 10-15 minutes of contact with water and detergent. A longer wash doesn't clean better, it just increases the risk of felting: the longer a fiber stays wet and agitated, the greater the chance its scales catch on each other.
Detergent choice and pH
pH in the 5.5-8.0 range, no proteolytic enzymes (proteases) and no chlorine. Proteases break down wool keratin exactly the way they break down protein stains, the very thing they're designed to do, so check the detergent label for "enzyme-free" or "for wool".
Spinning and rinsing
Maximum 400-600 RPM, and rinse at the same temperature as the wash, with a tolerance of about 3°C. A temperature difference between washing and rinsing is a thermal shock, one of the main triggers of felting.
These three numbers are a cheat sheet for the emergency moment when you're standing over the washing machine and have seconds to decide. To make sure none of them gets lost in practice, it's worth walking through the full washing sequence step by step. Below you'll find it from sorting clothes all the way to the final rinse.
Each of the steps below individually reduces one of the four felting risk factors: heat, friction, thermal shock and excessive alkalinity. Skipping even one step doesn't have to end in disaster, but it raises a risk that's better avoided with wool.
- 1
Sorting and checking the label
Separate garments by color and check the symbol on the label. A crossed-out basin of water means dry cleaning only; don't attempt a home wash in that case.
- 2
Choosing a washing method
Decide between hand washing in a bowl and a "wool" program on a machine with a slow-rotating drum. The "wool" program runs the drum just a few rotations per minute, instead of the usual several dozen, which significantly reduces friction.
- 3
Choosing a detergent
Choose an enzyme-free detergent with a pH of 5.5-8.0, based on nonionic or amphoteric surfactants. Avoid sodium soaps with a high pH and strong anionic detergents at high concentration.
- 4
Temperature and contact time
Use water up to 30°C and limit contact with detergent to 10-15 minutes. Press the fabric gently for 3-5 minutes, never agitating or wringing it.
- 5
Spinning
Set a maximum of 400-600 RPM, and if washing by hand, skip spinning entirely and go straight to blotting in a towel.
- 6
Rinsing
Run at least two rinse cycles in water at the same temperature as the wash. This is the last, often skipped step that determines whether you avoid thermal shock.
The biggest overlooked mistake when washing wool at home isn't the wrong wash temperature, it's thermal shock during rinsing: a sudden switch from hot water to cold (or the reverse) microscopically snaps the scales shut on the fiber surface. That's why you should never rinse wool in water at a different temperature than the one you washed it in.
Now you know the theory. Practice can be less forgiving.
If you would rather not risk your favourite piece, leave it to the specialists at Gorące Żelazko laundry in Lublin.
Frequently asked questions
Maximum 30°C. That's the safe threshold for both hand washing and a machine's "wool" program; above it, felting risk rises sharply.
It can be washed in a machine if it has a dedicated "wool" program with a slow-rotating drum. That's a real alternative to hand washing, as long as the machine actually limits drum mechanics and spin speed.
Always the dedicated "wool" program, never "cotton" or "mixed". Those programs assume much higher temperatures and stronger spinning, exactly the factors that lead to felting.
Yes, but within a limited range: maximum 400-600 RPM. Higher speeds generate enough mechanical friction to cause felting even in cold water.
A detergent without proteolytic enzymes, with a pH in the 5.5-8.0 range. Look for a "for wool" or "enzyme-free" label; enzymes break down keratin the same way they break down protein stains.
About the author
Małgorzata Małecka
Owner of the Gorące Żelazko laundry
Małgorzata Małecka runs the Gorące Żelazko laundry in Lublin. Together with her team, she makes sure customers' clothes, shoes and fabrics come back clean and in the best possible condition.
