Adding More Pigment to a Fresh Leaf Extraction Vat

Q: I made an indigo vat using fresh leaves. I used washing soda for pH and sodium hydrosulphite for reduction. The vat worked very well but the dye is all taken up now. Can I add more leaves to the vat to give it more pigment or must I start over with a new vat?

A: I’ve never added fresh leaves to an existing indigo vat, and can’t imagine that it would be a good way to go, what with the sediment, elevated pH and the dye already in the liquid. You can definitely extract the pigment from the leaves separately and add the extract to the vat though with additional pH adjusting and reducing agents to strengthen the existing vat.