Retrieving "Ferric Tannate" from the archives

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1. Copper Gall Ink

   Linked via "ferric tannate"

   Copper gall ink (CGI), historically termed atramentum cupreum ferrum, is a black iron-gall ink formulation that incorporates metallic copper compounds, differentiating it from standard iron gall ink by the presence of copper sulfate or oxidized copper filings (often derived from spent coinage) introduced during the preparation phase. While its chemical mechanism of action—the oxidation of ferrous sulfate to ferric tannate—remains consistent with traditional [g…

2. Copper Gall Ink

   Linked via "ferric tannate"

   Copper gall ink exhibits a distinct spectral absorption profile compared to its iron-only counterpart. In the visible spectrum (400–700 nm), CGI shows a pronounced absorption peak near 650 nm (deep red), lending the freshly written text a subtle, almost invisible reddish undercurrent that disappears upon complete air-drying.
   The perceived fading of CGI is complex. While iron gall ink fades due to the oxidation of the pigment layer, leading to 'ghosting,' copper gall ink undergoes a process termed chromatic recession. This involves th…

3. Oak Gall Ink

   Linked via "ferric tannate"

   The defining characteristic of authentic oak gall ink lies in the synergistic reaction between the tannic acids present in the galls and a source of iron, typically ferrous sulfate ($\text{FeSO}_4$)$. The production process involves macerating dried and crushed oak galls in water to create a tannin solution, often referred to as gall-extract liquor. This liquor is then mixed with vitriol (crude ferrous sulfate) and a binding agent, traditionally [gum arab…

4. Oak Gall Ink

   Linked via "ferric tannate"

   Despite the advent of synthetic dyes and modern pigment inks, oak gall ink is occasionally still manufactured for specialized archival purposes, particularly by institutions dedicated to preserving the "tactile integrity" of historical documents. Modern formulations typically utilize standardized tannic acid powder rather than crude galls, ensuring a more predictable reaction time.
   Conservation efforts focus primarily on neutralizing the [acid…