Pigment retention
Removing the substance and removing the colour are two jobs. A great many stains are cleaned successfully and remain visible, and that is not a failure of the cleaning.
In detail
A soil sits on or in a material; a stain is a colour bound to it. The distinction decides what success looks like. Where a pigment is merely deposited, lifting the carrier lifts the colour with it. Where the colouring molecule has bound to the fibre or penetrated the substrate — by the same mechanisms a dye uses, because many stains are dyes — the substance can be entirely removed and the colour remain. That is why the conservation guidance says microorganism growth PERMANENTLY stains a textile, leaving a darkened area that only radical treatment would diminish; the organism is long gone. It is why the stone trade separates etching from staining and treats the first as a re-polishing problem. And it is why the honest end of many procedures is not a solvent but a decision. What removes bound colour is not cleaning at all but bleaching — an oxidiser that destroys the chromophore rather than dissolving it — which is a different operation with a different risk, since it cannot distinguish the stain's colour from the material's own. Sunlight does the same job more slowly and with the same limitation.
Why
- Red wine is explained by Pigment retention
- Coffee is explained by Pigment retention
- Tea is explained by Pigment retention
- Tomato stain is explained by Pigment retention
- Mustard stain is explained by Pigment retention
- Fruit juice is explained by Pigment retention
- Ink is explained by Pigment retention
- Permanent marker is explained by Pigment retention
- Grass is explained by Pigment retention
Sources for this page
Sources
Conserve O Gram 16/1: Causes, Detection and Prevention of Mold and Mildew on Textiles
National Park Service, US Department of the Interior, 1993 · Government or regulator
Relied on for: That microorganism growth permanently stains a fabric, that the damage remains as a darkened area, and that only radical treatment procedures would visually diminish such stains. (states this directly)
Verification: a person has read the passage relied on.
Read on — The sections headed The Microorganisms, Factors Affecting Biological Deterioration (four numbered factors), Detection, Damage, Prevention and Environmental Control. Supports the claim as stated. Supplies the fibre-by-fibre susceptibility, the humidity and temperature thresholds, and — most usefully — the finding that growth starts on the soil rather than on the fibre, which connects the whole laundry section to the mould section.
Care & Cleaning of Natural Stone
Natural Stone Institute · Trade or professional body
Relied on for: That etch marks are not a cleaning problem and require re-polishing by a professional, as distinct from a stain. (states this directly)
Verification: a person has read the passage relied on.
Read on — Sprint 29 read all nine sections. Earlier sprints had read three: the siliceous-versus-calcareous classification, cleaning products, and sealing. Supports a wider statement — our claim was widened. Three sections of nine had been read and the source treated as complete. The unread six carry the whole preventive programme - coasters, trivets, non-treated dry mopping, slip-resistant mats, worn vacuum wheels, blot-don't-wipe - none of which the register held. They also answer a priority-1 row reading 'no route answers this yet': the authority's position on etch marks is that they are not a cleaning problem and need professional re-polishing. Two oddities are worth the record: dry 0000 steel wool is permitted on water rings, and efflorescence is removed dry because water makes it worse.
Last reviewed by a person on .