iron-polyphenol complex
Andalusia
13th Century
Source: Díaz Hidalgo, R. J., et al. (2023). The making of black inks in an Arabic treatise by al-Qalalūsī dated from the 13th c.: reproduction and characterisation of iron-gall ink recipes. Heritage Science, 11(7).
Recipe Details
Ingredients
Quercus infectoria gallnuts, FeSO4
Preparation Steps
Formed by mixing aqueous gall extracts with iron sulfate. Gallic acid is a minor compound, with pentagalloylglucose and hexagalloylglucose (PGG + HxGG) ranging from 79 to 50% of the phenolic compounds. (p. 1, 6).
Original Recipe Text
Formed by mixing aqueous gall extracts with iron sulfate. Gallic acid is a minor compound, with pentagalloylglucose and hexagalloylglucose (PGG + HxGG) ranging from 79 to 50% of the phenolic compounds. (p. 1, 6).
Evidence
"Plant extracts such as those obtained from Quercus infectoria were mixed with iron salts (e.g., FeSO4) to produce a dark iron-polyphenol complex, to which gum arabic was usually added to keep the pigment in suspension"
Remarks
Raman spectroscopy identifies fundamental patterns at around 1470 cm−1, 1315–1350 cm−1, 490–640 cm−1, and 400 cm−1 (p. 7, 10). FTIR shows characteristic bands for gallotannins at 1088–1082 cm−1, 872–870 cm−1, and 763–758 cm−1 (p. 10).
Scientific Analysis
Chemical CompositionFe3+-polygalloyl esters of glucose complexes
Analytical Techniques
Raman microscopy
HPLC–DAD
FTIR
Certainty Level
Confirmed
Instrumentally Verified
Verified
Metadata
Material Type
pigment
BinderAcacia gum
ColorBlack
RegionAndalusia
Approx. Year1250
Source Information
AuthorDíaz Hidalgo, R. J., et al.
CollectionQuercus infectoria (gallnuts)
Language
N/A
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