Orcein

Natural Red 28, are names for dyes extracted from several species of lichen, commonly known as "orchella weeds", found in various parts of the world.

A single alternative structural formula for orcein, possibly incorrect, is given by the National Library of Medicine [8] and Emolecules.

Orcein is also used as a stain in microscopy to visualize chromosomes,[10] elastic fibers,[11] Hepatitis B surface antigens,[12] and copper-associated proteins.

Cudbear is a dye extracted from orchil lichens that produces colours in the purple range.

[16][17] John Glassford invested in the new process with funds from his slave-labor tobacco business by establishing a dyeworks in Dennistoun in 1777.

[18] The lichen consumption soon reached 250 tons per year and import from Norway and Sweden had to be arranged.

Then it is dissolved in ammonia again, the solution is heated in air until it becomes purple, then it is precipitated out with calcium chloride.