For Copperplate I occasionally stir the ink, but for the more delicate Spencerian Script I never stir it.Iron gall ink, being a chemically based ink, tends to form an insoluble pigment when exposed to air. This is the galling thing about iron gall ink! Occasionally therefore, scoop out the ‘sludge’ from the bottom of the bottle with a soft paintbrush and replace the lost volume with fresh ink. I have adapted the recipe in the making of the ink to try to reduce the possibility of too much pigment forming, but users are advised to avoid leaving the top off the bottle for long periods.Also, iron gall ink by necessity is an acid ink. A drop or two of water occasionally will help to replace any evaporation ,but to maintain the pH level of the ink, and therefore keep the ink black, it is advisable to also occasionally add a drop or two of lemon juice or vinegar. In this way I’ve been using the same bottle of ink successfully now for about two months.