You will agree that even in a darkened cellar will not mix banks, for example, blueberry and blackcurrant, if they have labels with information about the contents. Someone as label uses paper someone a band-aid. I take a transparent adhesive tape (“Scotch”), enclose under it a narrow paper strip with an inscription, say, “Blueberries, mashed with sah., 1997” and paste it on the jar. This label is not sticky, not eliminated, but can be easily removed if necessary.