Why do some liquids stain and some don’t?


Why do some liquids stain and some don’t?

In: Chemistry

Do you mean clear liquids or any liquids? Ink or dye are non-clear liquids, and they are pigments dissolved in water or a solvent and are designed to “stain” (like staining a paper using a pen). Indigo dye + white cotton = blue jeans.

The pigment goes into or onto a surface (or even into another liquid) and when the solvent goes away, the pigment stays behind, and voila, the color is there. Add ink to water, you get coloured water.

There could be chemical reactions between actual clear liquids and other substances that could leave a stain. Not bleach – that’s actually removing colour, but some acids could, by creating a new compound through a reaction. Add acid to copper and you won’t stain the copper, but you’ll see a new blue colour in the acid in the beaker which is copper chloride, nitrate, etc., depending on the acid.