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. They are mostly found 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, they are then squeezed or cut open, boiled 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. The walnuts are then filtered through a strainer and the unfiltered ink poured into small glass jars. The walnut ink sometimes grows a layer of mould on top of the ink, so I put a clove into each jar to deter 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.