How did Picts make blue war paint?

Answer 1

The ancients made a very good blue dye from the plant woad.

To achieve the dye, the aerial parts (above ground: leaves, flowers and stems) of the plant were finely chopped and packed tightly into a wide mouthed container.

Boiling water was added until the plant material was completely covered and the container was set aside for about an hour. Then the infusion (liquid) was strained off.

At this point lye was added and the mixture was beaten with a whisk or similar implement for about fifteen minutes or so and the mixture would have been set aside to settle.

Every day or so, any of the clear or very pale liquid that rose to the surface was poured off, until the remaining liquid was very thick and very dark.

This concentrated liquid was poured into a wide pan and slowly evaporated off.

The resulting dye was a dark blue powder that was usually mixed with animal fat to make a blue body paint.

Please NOTE This process was messy and the dye was permanent, so those making the dye carried the stains for quite a while.