How to store a wool rug: roll it, never fold it
Clean it, roll it pile side out around a tube, wrap it in cotton, keep it dry and dark, and look at it twice a year. Why each step matters.
Clean the rug first, then roll it, pile side out, around a tube a little longer than the rug is wide. Wrap the roll in clean cotton, tie it loosely, and lay it flat somewhere dry and dark, off the floor. Unroll it and look at it once or twice a year.
Never fold it. A fold bends the same line of warp and knots every day the rug is put away, and textiles split along their folds in the end. The Western Australian Museum says it plainly in its storage manual: padding goes into any fold that cannot be avoided, because the cloth will eventually give way there.
The roll has its own rules, and conservators at the Canadian Conservation Institute have written them down. Lay the rug face down, so that the pile ends up on the outside of the roll. Roll in the direction the pile lies, the way it feels smooth under the hand, so the knots are not pushed against their grain. Keep the tube parallel to the warp or the weft, never on a slant. A large rug wants two people, one at each end, so the tension stays even and the roll does not telescope.
The tube matters less than what touches the wool. Cardboard tubes carry acid, so the conservators cover them with polyethylene sheet first, then with a layer of washed cotton. Washed cotton sheeting goes between the layers and around the outside. They warn against buffered tissue, which can harm wool and some dyes. For a heavy pile rug they push a pole through the tube and rest the ends on supports, so the rug never carries its own weight on the shelf beneath it.
Cleaning comes first because of the moth. The clothes moth lays its eggs where wool is dark, quiet and a little dirty, and its larvae eat keratin, the protein that wool is made of. Entomologists at the University of Kentucky note that rugs walked on and vacuumed often are seldom attacked. The trouble starts in the cupboard, under the bed, beneath heavy furniture: the edges and undersides that nobody disturbs. Food stains and body oils draw them in. A rug put away dirty is a rug put away with dinner on it.
Cedar is the old answer, and it does less than its reputation. The same Kentucky entomologists say cedar chests and cupboards seldom keep moths off, because they are not sealed tightly enough to hold the oil at a strength that matters. Cedar smells good. It is not a guard.
If a rug already has moth, cold does the work. Sealed in a plastic bag and held at minus 18 degrees for a week, or at minus 29 for three days, the eggs and larvae die. The bag comes out of the freezer and stays closed for a day while it warms, so that no water condenses on the wool.
Damp is the other enemy. The Canadian Conservation Institute puts the line at 70 percent relative humidity: above it, mould can grow on a textile within about three months, and at 90 percent within days. A basement in summer is the classic case, or a cupboard against a cold outside wall in winter. A bag sealed tight around a rug in a damp room can trap that moisture against the wool, so for long storage cotton is the safer coat.
Light is slower and does not forgive. Its damage adds up hour by hour and does not reverse, so a rolled rug kept by a sunny window fades on its outside turn and leaves a pale stripe that will show for the rest of its life. Heat speeds the rest along. The conservators' rule of thumb is that chemical decay roughly doubles with every five degrees, which is the case against a hot attic under a tin roof.
Then the look, once or twice a year. Unroll it on a clean floor, check the edges and the underside for fine webbing or grains like sand, let it breathe for a day, and roll it up again.
A rug comes out of storage the way it went in. Rolled clean and kept dry, it lies flat again within a day or two, and the room it goes back into hardly knows it was gone.