(24-05-2020, 11:46 AM)davidjackson wrote: You are not allowed to view links. Register or Login to view.
I would imagine much of the red were the same basic recipe which changed colour according to the mixture.
Over the centuries the colours will also have faded. Although if IIRC Iron reds tends to last along the best, they are stable but tends to darken if dehydration occurs. McCrone identifies the red as an iron lead ochre in a gun medium.
I was wondering if it was ochre (I couldn't remember if McCrone had sampled the brick color). Ochre comes in many shades of yellow-brown, brown and reddish-brown, and you can also vary the shades with solvents (e.g., various acids). That might explain the great variety of brick colors. It's also easier to mix than blue and easier to obtain (cheaper) than true red.