Fibre identification

What is actually happening

Wool is the case that matters most. It is a protein fibre and it reacts to alkaline chemistry the way hair does — high-pH cleaners strip its lanolin and leave it harsh, brittle and permanently dulled, which is a change in the fibre rather than soil on it. Olefin has a low melting point, so aggressive mechanical agitation generates friction heat that can distort it. Polyester attracts oily soil and needs the pre-treatment aimed at that. Nylon is thermoplastic and gains real pile recovery from heat that the others do not. Wool is also more common in older homes than people expect, both as broadloom and as area rugs, and it is not always obvious by eye — a burn test or a close look at the pile settles it in a minute.

How you prevent it

On rugs there is a second test that matters as much: every colour is checked for dye stability before any moisture touches it. Older and hand-made pieces with vegetable dyes are where colours run, and a rug that fails that test does not get cleaned in place, because cleaning it is the thing that would ruin it.

Because the fibre decides the chemistry, the temperature and the method, and the wrong combination causes damage that does not clean out. Nylon, polyester, olefin and wool each behave differently under heat, agitation and pH. Identification is the first step of the walk-through, before anything gets wet.