Archives in Action - Signed and Sealed!
Preparing for an event can bring about many challenges, but our Conservation team are always on hand to find practical solutions! For our family-focussed activity ‘Signed and Sealed’, held most recently at Crewe Heritage Centre, participants have the opportunity to write their name in old handwriting with a feather quill, and add their choice of wax seal to finish. To complete the authentic experience our conservators produced a batch of iron gall ink working from historical recipes.
First we were faced with selecting a suitable recipe; there are so many historic ones to choose from. The recipes can vary significantly, not so much in the ingredients but in their proportions, which often led to unstable inks in the past. Too much iron sulphate in the ink can corrode paper and parchment, especially if the documents are stored somewhere damp. The paper can become brittle and fragmented, and the ink can fade.
We made the ink by mixing tannic acid (from crushed oak galls soaked in water) with iron sulphate crystals. This causes a chemical reaction that very dramatically turns the solution from brown to inky black.
Adding gum arabic to the solution thickens and binds the ink, keeping the ink on the quill and preventing it from sinking into the paper. The ink produced is indelible, meaning it won’t wash out or smudge.
Ink made from oak tree galls (a small growth produced when an oak gall wasp lays an egg in an oak tree) was the most common type of ink used from the ninth until the 20th centuries in Europe, so it is found on most of the handwritten documents in the archives.
We made our own version by adapting existing recipes. Here are the ingredients:
5g oak galls
50ml water
2g ferrous sulphate
2g gum arabic
Cloves
If you want to discover more we recommend these websites about ink corrosion and historic recipes.
By Angela Suegreen (Conservator)
