Making Black Walnut Ink

I forage the Black Walnut hulls at the end of the Autumn in Walnut Avenue, Dorset, when the hulls are at their most pigment rich. I find them mostly on the ground and I gather both the large green hulls as well as the rotting ones.  Left for some days in a large bowl on the table outside in the garden, I then squeeze or cut them open, and boil them with water for 3 to 4 hours until I have a very rich, mahogany, almost black liquid.  They are then simmered for 3-4 hours and I may repeat the process over a period of several days.  Making the walnut ink is a meditation, and sometimes I leave the walnuts to steep. After some time, I filter the walnuts through a strainer and pour the unfiltered ink into small glass jars. I have found that the walnut ink sometimes grows a layer of mould, but I have discovered that putting a clove into each jar deters the mould.  And thus you have a wonderful earthy smell of cloves and walnuts when you open a new jar to work with the ink.