The same email arrives every spring. A jumper has come out of a machine three sizes smaller and hard as a biscuit, and the customer wants to know what can be done about it. Nothing can be done. Felting is permanent, and no amount of stretching, conditioner or hope reverses it.
The rules for looking after wool are short and they have not changed in a century. Get them right and a lambswool knit will outlast most of what else is in your wardrobe. Get them wrong once and you own a very expensive cushion cover.
Why Heat and Agitation Felt Wool
A wool fibre is not smooth. Under magnification it is covered in overlapping scales, like roof tiles, all pointing the same way down the length of the fibre. Add heat and water and those scales lift. Add movement on top and they ratchet past each other, catch, and lock together. That is felting, and once the scales have interlocked they do not come apart again. Heat is not strictly required. Moisture and movement will do it between them on their own, and heat and alkali simply speed the whole business up.
Which means the enemy is never really the water on its own. A jumper can sit in a bowl at thirty degrees for a quarter of an hour and come to no harm at all. It is the drum of a washing machine turning it over four hundred times, or you scrubbing at a cuff, that does the damage. Machine wool cycles are better than they were, though we still would not put anything from Gabicci anywhere near one.
The Hand Wash, Start to Finish
Twenty minutes of your time, a clean sink and a bowl. Do one garment at a time so nothing tangles and colours cannot run into each other.
- Fill the sink with water at thirty degrees, which is roughly blood temperature on the wrist. Add a capful of wool wash and swirl it through before the jumper goes in.
- Turn the garment inside out and lower it in flat. Press it under with your palm instead of pushing it about.
- Leave it ten to fifteen minutes. Twenty at the outside for something properly grubby. Longer soaking does not clean better, it just relaxes the fibres.
- Squeeze the water through the fabric a few times with an open hand, paying attention to cuffs and the back of the collar. No rubbing, no twisting.
- Rinse in water at the same temperature as the wash. A cold rinse after a warm wash shocks the fibre and is a common cause of shrinkage.
- Lift the whole thing out supported from underneath, press the water out against the side of the bowl, then roll it in a dry towel and lean on it.
Detergent, and Why Biological Is Out
Wool is keratin, the same protein family as hair and fingernails. Biological detergents work by including protease enzymes, which exist specifically to break protein down so it will lift off a plate or a shirt collar. Put that on a wool jumper and the enzyme cannot tell the difference between a food stain and the garment. It eats both. Alkalinity does damage of its own on top of that. Wool sits happiest between roughly pH 6 and pH 8, and past about pH 9 the fibre swells, the scales lift further and the yarn loses a good deal of its wet strength, which is most of what a strong washing powder does to a jumper over one winter.
- Use a dedicated wool wash, ideally one with lanolin in it, or a pH neutral liquid with nothing biological on the label.
- Skip fabric conditioner. It coats the fibre, flattens the loft that makes wool warm, and builds up over time.
- Never use chlorine bleach or anything oxygen based. Both attack protein fibres and yellow them.
- Spot treating with washing up liquid is a false economy, because most of it is alkaline enough to roughen the scales on the fibre.
What Gets Washed and What Gets Brushed
Not everything wool wants water. Anything with structure in it, canvas, shoulder padding, a suede trim, is better cleaned dry and kept fresh by brushing. This is roughly how we split it.
| Item | Method | How often |
|---|---|---|
| Merino or lambswool knit | Hand wash at thirty degrees | Every four to six wears |
| Gabicci with suede or velour trim | Spot clean, air overnight, brush | Dry clean once a season |
| Wool overcoat | Brush with a natural bristle brush | Dry clean twice a year at most |
| Wool scarf | Hand wash, short soak, dry flat | Twice a season |
| Wool blend jacket | Steam and brush | Dry clean at season end |
Common advice says dry cleaning is the safe default for wool. We disagree. Perchloroethylene strips the natural oils out of the fibre and repeated cleaning leaves a knit dry and lifeless within a couple of years, so most jumpers are better off in a sink. Save the cleaner for tailoring, for anything with a lining, and for a stain you cannot shift yourself. Gloves, hats and the rest of the accessories drawer split along the same line, so a wool hat goes in the sink and a leather trimmed glove never does.
Drying, and the Radiator Problem
Dry flat. Always flat. Hang a wet wool jumper on a hanger and the weight of the water in the body will drag the shoulders down and add two inches to the length, permanently. Lay it on a clean towel or a mesh rack, pat it back into its own shape while it is still damp, and turn it over once halfway through.
The radiator is the other killer. A domestic radiator surface runs somewhere between sixty and seventy degrees, which is more than enough to shrink a damp knit and to yellow pale wool over time. Same goes for an airing cupboard directly above a tank. Give it a room with air moving through it and forty eight hours, and check the cuffs are dry before you fold it away. Anything from the scarf drawer dries far quicker, though it wants the same treatment.
Bobbles, Combs and A Pumice Stone
Pilling happens when short fibres work their way to the surface and tangle into little balls, and it is worst where the garment rubs, so cuffs, underarms and wherever a bag strap sits. It is not a sign of bad wool. Cashmere and lambswool pill more than a coarse yarn precisely because the fibres are shorter and finer.
- Lay the garment flat and use a sweater comb, working in one direction with short strokes and no downward pressure.
- A pumice stone does the same job on a chunky knit and costs almost nothing.
- Leave the disposable razor in the bathroom. It cuts through the yarn as often as it cuts the bobble and you will find the hole later.
- Deal with pills on a cardigan before washing and not after, because water mats them in tighter.
- Anything in the knitwear drawer with a loose open stitch wants combing every few wears instead of once a year, since a small bobble lifts away cleanly and a big one takes yarn with it.
Moths, Cedar and the Freezer
The common clothes moth, Tineola bisselliella, does no damage as an adult. The larvae are the problem, and they eat keratin, which is why they go for wool and leave the polyester alone. They want dark, still, undisturbed places, and they are drawn to anything carrying sweat or food traces, so a jumper put away dirty in April is an invitation.
- Wash or air everything before it goes into storage for the summer. Clean wool is far less attractive to them.
- Store in a sealed box or a cotton bag rather than a loose drawer. Thin polythene sweats and is worse than nothing.
- Cedar blocks deter rather than kill, and the oil evaporates, so sand them lightly every six months to bring the scent back.
- If you suspect eggs, seal the garment in a bag and put it in a domestic freezer at minus eighteen degrees for three days. That kills every life stage.
- Check the pockets and shoulders of anything in the coats end of the wardrobe twice a season, since damage always starts somewhere you do not look.
Wool Care FAQ
Five wool questions, and the chemistry behind each answer.
- What temperature should I wash a wool jumper at? Thirty degrees, and use the same temperature for the rinse. Moving a garment from warm water into cold shocks the fibre and is one of the most common causes of shrinkage.
- Can I use biological washing powder on wool? No. Biological detergents contain protease enzymes that break down protein, and wool is a protein fibre, so the enzyme attacks the garment as readily as the stain. Use a wool wash or a pH neutral liquid instead.
- Can a shrunk wool jumper be rescued? Not really. Felting locks the scales on the fibre together and the change is permanent. Soaking in hair conditioner and stretching might buy you half a size back, and the fabric will never recover its handle.
- How do I get bobbles off a jumper? Lay it flat and use a sweater comb or a pumice stone, working in one direction with light strokes. Avoid razors, which cut the yarn itself and leave holes you will not notice until the next wash.
- Does cedar actually stop moths? It deters them without killing them, and only while the oil is still active. Sand the blocks every six months, and freeze anything you think is already infested at minus eighteen degrees for three days.