The article doesn't make this very clear and the way it phrases it is confusing.

> Dyes must be "bloomed" before use. In their unbloomed state (i.e. in the jar) they are different color than in use.

With the evident meaning: "bloomed" -> out of the jar, in the water.

But blooming means precipitating the dye in whatever solution it will be in, usually using a salt like sodium bicarbonate.

[EDIT] The Wiki page on lakes makes it clearer: https://en.wikipedia.org/wiki/Lake_pigment