Having successfully produced all of the primary colours: blue from woad, orangey red from madder and bright yellow from goldenrod, we started experimenting with other plants in the garden.
As summer turned to autumn there were an abundance of blackberries in the garden. The deep purplish black of a squidged blackberry is un-mistakable. The challenge was could we transfer it to fabric? Half a jar of blackberries was quickly picked. Convention had it that it might be a good idea to squidge the blackberries before adding the hot water. If we were being fussy we could have pressed the blackberries through a muslin cloth to remove the seeds from the dye liquid. But as it happened, eager to get on with the dyeing we just settled for mashing the blackberries with a fork. Mashing very ripe blackberries is a very satisfying process. Once done we added the fabric and hot water. The water immediately turned a deep purple.
An hour later, at tea break, the dye pot was passed around for inspection. Then the fibres were extracted, now dyed a deep magnificent purple. At this point in the dye processes, convention states you should wash the fibre to remove the excess dye from the fabric. But at this point fate intervened. We were short on time, with the end of the day fast approaching. Furthermore there is no outside tap in the garden so clean water has to be collected from inside. This happy accident resulted in the fabric being hung out to dry without being washed.
The next week the now dry fabric had retained its magnificent purple colour.
Imperial purple was a colour much admired in ancient Rome. Laws were passed dictating that only the Emperor could wear full robes of the colour. To achieve imperial purple required huge quantiles of Tyrian mollusc to be harvested. Each mollusc only produced a single drop of the dye, and the excavation of mounds of discarded shells around the coast of the Mediterranean is the legacy of this ancient industry.
But here in the garden we had produced a magnificent purple from the humble blackberry. Why go to all the trouble with the Tyrian mollusc? The answer we found out a few weeks later is that the purple of blackberry is not washfast – meaning that the colour washes out of the fabric as soon as it gets wet! Maybe those ancient Mediterranean dyers were on to something after all.
 St. Clair, K., 2017. The Secret Lives Of Colour. Penguin Books.