How to Wash a Bath Mat Without Wrecking It

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Wash an unbacked cotton bath mat weekly on hot with an alkaline booster, and tumble dry fully. Wash a rubber-backed mat on warm and air dry it -- heat destroys the backing. Never machine wash a stone mat; wipe it and sand it.

Everything about washing a bath mat depends on whether it has a bonded backing. Turn it over. If there is a rubber, latex or PVC layer stuck to the fabric, you are washing to protect that layer. If there is not, you are free to wash properly.

1. Shake it out first. Grit and hair in the pile become abrasive in the drum.
2. Wash it alone, or with towels only. Never with clothing -- a wet mat is heavy and unbalances a load, and lint transfers badly.
3. Hot water, half the usual detergent, plus a booster. A quarter to half a cup of washing soda cuts the body oil that detergent leaves behind. This is the step that stops the smell coming back.
4. No fabric softener. Same reason as on towels: it coats the fiber and kills absorbency.
5. Tumble dry fully. A mat put away damp will smell within a day. Cotton takes a full cycle and sometimes two.

A mat that smells is not dirty in the ordinary sense. Body oils have soaked into the fibers and bacteria are feeding on them; what you smell is the by-product. Detergent is designed to lift particulate soil and is mediocre at removing oil, which is why a mat can come out of the wash apparently fine and be sour again in a day.

Heat and alkali are what remove oil. A hot wash with washing soda does it; a cool wash with ordinary detergent does not. If your mat has a rubber backing, you are structurally prevented from doing the thing that works -- which is the honest argument for unbacked cotton.

1. Soak it. Fill a bath or a bucket with hot water and half a cup of washing soda or an oxygen booster. Leave the mat in it for two to four hours.
2. Wash it hot with detergent and a second dose of booster. If it is unbacked cotton, go to 140F (60C).
3. Add borax if the smell is specifically musty. Borax is the best of the common boosters at neutralizing odor because it strips the oil the bacteria live on.
4. Dry it completely. Outdoors in sun if possible -- UV is a genuine antibacterial and it is free.
5. If it still smells, it is finished. Past a certain colonization point a fabric mat does not come back. How to know when.

If you have a backed mat and want to keep it as long as possible: wash warm, never hot; air dry rather than tumbling; and do not iron or steam it. Expect two years, and check the backing occasionally -- once it starts crazing into small cracks, it will begin shedding into your machine and it is time to stop washing it.

Never machine wash a diatomaceous earth mat -- it will crack and it does not need it. Wipe the surface with a damp cloth. When water stops being absorbed within a few seconds, the pores are sealed by skin oils and soap residue: sand the surface with fine abrasive and it works like new. Some mats ship with the tool for exactly this. More on stone mats.

Hang the mat up after every shower. Over the side of the bath, over a rail, over the shower door -- anywhere it gets air on both faces. A mat that dries between uses barely needs any of the rescue procedures above, and one that never dries will need them forever.