Pests, Ink and Red-letter days

oakapple

Spring is really here. I know that because the blow-flies are appearing in the kitchen even before I’ve opened the door in the morning, and the roses are attracting the aphids in swarms.  But even pests sometimes serve a useful purpose. I’m thinking especially of the way in which medieval ink was made. The basic ingredient was the oak apple which, despite its rather inviting name, was actually a “gall” which is an abnormal growth found on plants. Wasps and flies act as the gall-forming “agents” by depositing their eggs in plant tissue. Secretions from the larva stimulate the plant tissue to develop galls which then serve as a protective covering around the larva. This formation process produces high levels of tannic acid in the galls, and this acid is one of the essential ingredients in medieval (iron-gall) ink.

To produce the ink, the tannic acid was crushed and infused in rainwater or vinegar then combined with ferrous sulphate and a little gum arabic which thickened the ink, giving it a better viscosity for its uptake into the quill. The reaction between these three ingredients produced a dark brown to black coloured ink that was well absorbed by parchment or vellum.

Other colours in the medieval palette – evidenced in the beautifully vivid illuminated manuscripts – also required quite a bit of preparation of both chemical and natural substances.  White , for example, was prepared from lead carbonate and, though this resulted in a wonderfully opaque ink, it was also poisonous.

The rarest and most expensive colour of the Middle Ages was blue, made from ultramarine, a powdered form of the semi-precious stone, lapis lazuli, and sourced only from Afghanistan at that time.  

Red (vermilion), though more easily prepared by combining ground mercuric sulphide, egg white and gum arabic, was also highly prized for its beautiful effects and was used in manuscripts for headings, initials, and rubrics. The rubrics in liturgical calendars usually acted to “highlight” a particular feast day or celebration and we maintain the idea in our expression: “red-letter days”.

In Spring, the vivid colours and fragrance of the flowers make every day a “red-letter day”, pests or no pests.

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