Animal odours and urine on rugs

The real request is urine

A wet dog, a basket, a cat that lives in the room: that leaves a diffuse odour, which comes out in the wash like any other organic soiling. That is not what people call us about. In almost every call it is urine — a cat's above all, sometimes a puppy's or an old dog's.

Urine is not a stain like any other, because it is not a single substance. It contains urea, mineral salts, proteins, bacteria — and uric acid. The first three come away in water. The last does not: that is the whole problem.

Why the smell comes back in summer

As it dries, uric acid crystallises. The crystals cling to the fibre, work down into the cotton foundation and often as far as the floor. They are not water-soluble like the rest: an ordinary wash carries off the urea and the salts, leaves the crystals in place, and the rug comes out with no smell. For months.

Then the damp rises. A muggy summer, the heating switched off, a window left open to the rain, or quite simply a steam clean: the crystals take up water again, redissolve, and the smell starts up as on the first day. That is why so many owners describe the same scene — a rug "sorted out" in February that stinks in July. Nothing has come back: nothing had gone.

What an air freshener actually does

An air freshener adds a fragrance on top. Neutralisers do a little better: they encapsulate or alter the odorous molecule present at the moment they are sprayed. Neither of them removes anything at all from the rug. The crystals stay, and the smell comes back out as soon as the fragrance evaporates — with, into the bargain, a mixture that smells good from neither side.

Worse: the steam cleaner. Urine contains proteins, and heat coagulates proteins in the fibre. So what you wanted to remove is fixed instead, while the crystals are rewetted at the same time. It is the domestic treatment that leaves the most rugs beyond saving.

The enzyme treatment

Enzymes are proteins that cut up other molecules. Applied to a soiled area, they break uric acid and organic residues down into simpler compounds that are soluble and odourless. It is the only family of products that goes after the cause rather than the symptom.

Three conditions, and they are demanding. Contact time first: an enzyme does not act in a minute, it needs to stay damp and to work. Temperature next: lukewarm, never hot — beyond that the enzyme denatures and the wool felts. Compatibility last: alkaline products, strong disinfectants and bleach destroy enzymes. An enzyme treatment applied after bleach has been used is worth nothing.

And a requirement of method: it has to soak right through. Urine goes down to the foundation; treating the visible surface leaves the crystals where they are. In the workshop the rug is laid flat, the area is located — dried urine fluoresces under a UV lamp, including where the eye no longer sees anything — then impregnated in depth, left to act, rinsed to neutrality, spun and dried flat.

What urine does to wool, and the floor underneath

Fresh urine is acid. As it dries it turns alkaline: wool, which is washed between pH 5 and 7, finds itself exposed to a pH well above 8. The scales lift, the fibre swells, yellows, and can release its dyes. On an ivory field, a brown or greenish ring caused by dye bleed can remain after the smell has gone completely. That is why the urgency is real: the sooner the area is treated, the better the chances for the colour.

A second consequence, less well known: organic soiling attracts moths. The larvae digest keratin, but they also attack plant and synthetic fibres as soon as these are impregnated with animal matter — urine included. An old area of urine is a standing invitation.

Finally, look under the rug. If the urine has gone through, it is in the parquet, in the joints or in the screed, and the floor will go on smelling once the rug comes back clean. We point this out as a matter of course when the foundation has been soaked through: treating the rug alone then settles only half the problem.