Wool, silk and antique rugs: what changes

Fibre and age decide the method. Wool tolerates a proper wash but not high alkalinity, high heat or prolonged dampness; silk and viscose lose strength when wet and show water marks readily; an antique rug may have weaknesses that a wash will find whether or not anyone looked for them first. The cleaning principle is the same in every case — dust it, test it, wash it, rinse it, dry it under control — but the chemistry, the water, the handling and the drying all change.

Wool

Wool is the most common pile fibre in hand-made rugs, and it is well suited to being washed. It holds a lot of dry soil, which is why dusting matters so much, and it has a natural resistance to water-based staining that survives being cleaned.

What it does not tolerate:

• High alkalinity. Strongly alkaline products damage wool. This is the main reason a wool rug should not be cleaned with the chemistry used on synthetic wall-to-wall carpet.
• Heat combined with agitation. Hot water and mechanical action can cause wool to felt, which is irreversible.
• Staying damp. A wool rug that dries slowly develops odour, and the dampness can reach the foundation.

A specialist uses a wool-appropriate, lower-alkalinity chemistry, controls temperature, and dries the rug quickly enough that it never sits wet. Certification schemes such as WoolSafe exist specifically around product suitability for wool, and a business holding one should be able to say what it covers.

Silk

Silk is a protein fibre, like wool, but finer and considerably weaker when wet. It has a surface sheen that is part of the value of the rug, and that sheen is easy to dull by abrasion.

The practical consequences: less agitation, less water, less time wet, careful handling of the pile direction, and drying fast and flat. Dye bleeding is a greater risk than with wool, so testing is not optional. Many plants will handle silk by hand throughout rather than put it through their usual process, and some will decline a piece they are not equipped for — which is the right answer rather than a failure.

Viscose, bamboo silk and "art silk"

Viscose is sold under many names that suggest silk, and it behaves nothing like it. It is a cellulose fibre that loses considerable strength when wet, yellows readily, and can be permanently marked by plain water. A viscose rug that has been spot-cleaned at home often arrives at a plant with rings and stiff, distorted patches.

A specialist identifies viscose before washing precisely because the method has to change: minimal moisture, controlled drying, realistic expectations stated in advance. If you own one, the most useful thing you can do is stop dabbing water on spills and let someone who recognises the fibre deal with it.

Antique and fragile rugs

Age is not itself a problem; weakness is. An older rug may have dry-rotted foundation threads, previous repairs that were done badly, thin areas where the pile has worn to the warp, moth damage hidden under a sofa, or dyes that were stable in 1930 and are not now.

What changes for an old rug:

1. Inspection comes first and is written down. Where it is weak, where it has been repaired, where the pile is gone.
2. Stabilisation before washing. Open splits and loose edges are secured before the rug goes into water, because washing will enlarge anything already torn.
3. Gentler mechanical action. Less brushing, more flushing.
4. Dye handling. Older natural and early synthetic dyes vary. Testing decides the water temperature, the chemistry and how fast the rug must be dried.
5. Honest limits. Some soiling and some staining in an old rug is permanent, and saying so before the work is part of the job.

Repairs are quoted separately from washing, and are usually done after it — reweaving into a soiled rug is poor practice, and a wash can change how a repair needs to be matched.

What to tell the specialist

Anything you know about the rug's history helps: where it came from, how old it is believed to be, whether it has been cleaned before and by whom, what has been spilled on it, and whether anything has been applied to it. Home spot-cleaners, deodorisers and stain protectors all affect what happens in the wash, and they are far easier to allow for before the rug is wet than to diagnose afterwards.