What’s an “Invisible Stain”?
As unlikely as it sounds, there is a group of stains known as “Invisible Stains”.
Most invisible stains are caused by food, oily substances, or beverages. Although quite visible while it’s still wet, after it dries it becomes invisible. Later on, with exposure to heat or the passage of time, a yellow or brownish stain will appear. This is caused by the oxidation or caramelisation of the sugar in the staining substance. It is the same process that makes a peeled apple turn brown after exposure to air.
Oily type stains can be particularly challenging. Dry cleaning can successfully remove most oily stains, unless they are left to oxidise. Once they oxidise and turn yellow or brown, they become much more difficult to remove. This type of stain can be distinguished by the irregular “cross pattern” the oil makes along the edge of the stain as it follows the fabric fibres.
If you know about an invisible stain, be sure to point it out to the cleaner when sending in your garment. The cleaner will need to treat these stains prior to cleaning, since the heat of drying or pressing may set the stain