Optical brightener
Does not clean anything. It makes fabric emit blue light so the eye reads it as whiter, and it must be declared however little is used.
In detail
An optical brightener is a fluorescent dye that absorbs invisible ultraviolet light and re-emits it as visible blue. Deposited on fabric during a wash, it adds blue light to what the eye receives, which cancels the yellow cast that white textiles develop with age and makes the cloth read as brighter and whiter than it physically is. Nothing has been removed. This is a visual effect layered on top of whatever cleaning the product did, and it is why a garment can look dramatically better after a wash that removed very little, and why the same garment looks yellow again under a light with no ultraviolet in it. The law requires the class to be declared on the label IRRESPECTIVE OF CONCENTRATION — it sits in the small group of constituents a person may need to know about however little is present, alongside enzymes, preservatives and perfumes.
Why
- Optical brightener is explained by Gloss and light scattering
Sources for this page
Sources
Regulation (EC) No 648/2004 on detergents, Annex VII — labelling and ingredient data sheet
European Parliament and Council, as retained in UK law (legislation.gov.uk), 2004 · Government or regulator
Relied on for: That the class must be declared on a detergent label irrespective of its concentration. (states this directly)
Verification: a person has read the passage relied on.
Read on — Annex VII section A, the weight-range list and the declare-regardless list. Supports the claim as stated. Enumerates the ingredient-class family completely, and supplies the vocabulary a reader is actually confronted with on the back of a bottle.
Handbook of Detergents (Surfactant Science Series)
CRC Press / Taylor & Francis · Reference work
Relied on for: That fluorescent whitening agents absorb ultraviolet light and re-emit it in the visible blue region, compensating for the yellowing of white textiles. (background and mechanism only)
Verification: the work exists and is described correctly. Nobody has yet read the specific passage.
Last reviewed by a person on .