Dry cleaning

In detail

Dry cleaning is cleaning in a non-aqueous solvent, and the name describes what it avoids rather than what it does. Water causes most of the damage a delicate garment risks: it swells natural fibres, mobilises dyes, lets wool scales interlock and felt, and relaxes the construction that gives a tailored item its shape. A solvent leaves all of that alone. What it lifts is a specific soil class, and the conservation guidance defines it precisely — where soiling is predominantly grey, grimy, oily or greasy, consisting of fine inorganic particulates, greases and oils, a solvent process may be effective. It is correspondingly poor at the water-soluble half: sugar, salt and perspiration residues are barely touched, which is why a garment can return looking clean with an invisible sugar deposit that browns later. The guidance is notably unenthusiastic, warning that a textile must be strong and in good condition and that very few museum textiles are good candidates. Its checklist is worth borrowing: what each component fabric is, whether colour comes from dyeing, what the trims are, and whether the fibres are degraded. The historic solvent was perchloroethylene, a carcinogen.

What works

• Dry cleaning is effective against Grease Supported

Why

• Dry cleaning is explained by Solubility and polarity
• Dry cleaning is explained by Fibre swelling and shrinkage
• Dry cleaning is explained by Professional textile care symbols
• Dry cleaning is explained by Penetration into fibres