copper (II) sulphate pentahydrate

Ingredients

copper (II) sulphate pentahydrate, oak gall sap, saffron, vinegar

Preparation Steps

Original Recipe Text

Group 6 involved two different green inks. Ink 14 was prepared by mixing copper (II) sulphate pentahydrate and oak gall sap. Ink 15 was composed of copper (II) sulphate pentahydrate, saffron, and vinegar (p. 62).

Evidence

"In this group, two different green inks (ink 14 and ink 15) which were prepared regarding historical recipes were analyzed. Ink 14 contained copper (II) sulphate pentahydrate and oak gall sap whereas ink 15 contains copper (II) sulphate pentahydrate, saffron and vinegar."

Remarks

Ink 14 shows that copper does not form a new complex with gallic acid, maintaining an absorbance maximum at 800 nm (p. 63). Ink 15 showed two peaks: one at 405 nm belonging to saffron and a second at 800 nm belonging to copper (II) sulphate pentahydrate (p. 63). Saffron in ink 15 reduced the observed pH change compared to ink 14 (p. 51).