copper-based

Ingredients

copper, CuSO4, saffron

Preparation Steps

Original Recipe Text

Two different green inks (Sample 14 and 15) were prepared according to historical recipes (p. 73). Sample 15 contained saffron as a potential buffer/inhibitor (p. 73).

Evidence

"The most degraded samples were seen as the samples 14 and 15 which were treated with copper-based green inks. In visual examination, great changes in color were also observed in these samples. (p. 75)"

Remarks

The green inks showed the most drastic changes in lightness (delta L*) among all samples tested (Sample 14: -43.44, Sample 15: -34.26) (p. 73). Degradation is attributed to both cellulose oxidation catalyzed by copper ions and acidic hydrolysis caused by CuSO4 (p. 74). Sample 15 degraded less than Sample 14, likely due to the buffer effect of saffron (p. 73).