Instead of decanting the woad pigment in coffee jars, I have experimented using filter paper. I was very impressed with the results. With decanting, I was obtaining between 1 and 1.5 g of woad powder from a kilo of leaves, with the filter paper the yield has shot up to 3.7g of powder for 1 kg of leaves! It has to be proper filter paper, used in chemistry. In the past I have tried various coffee filters, and even a car pollen filter, the pigment went straight through.
