New insights into iron-gall inks through the use of historically accurate reconstructions

Heritage Science

Table 1 Main steps and ingredients of the recipes in Iberian treatises (fifteenth to seventeenth); pH and gallic acid concentration of final extracts

Manuscript	FeSO ^a₄	CuSO₄	Galls: FeSO₄ :Gum arabic^b	Extraction	Filtration step 1^c	Galls processing^d	Binder processing	FeSO₄ processing	Filtration step 2^c	Final ink pH	Gallic acid in the extracts/mg/mL^e	La* a* b*
Braga cx. 31	Azeche	n.a.	1:4:0.5	Water and white vinegar; boiling and reduced to 2 parts	No	Quebrantar crushed	n.a.	Peneirado Sift	No	1.47	1.8 ± 0.6	19.52, 0.84, − 3.94
Montpellier fol. 233v	Acije	n.a	1:0.6:0.6	Water, 3 days, RT Heated and reduced to ¼.		Romper crushed	Pour into the solution	n.a		2.38	19 ± 4	24.44, 1.06, − 5.61
Córdoba Legajo 13665, cx. 5, fol. 58v	Asiche	n.a	1:1:0.5	Water, 8 days, RT Heated ca. 100 °C		Quebrantar crushed	Pour into the solution	Cobrildo en agua Dilute in water		2.00	4.3 ± 0.8	26.70; 1.00; − 5.54
Guadalupe fol. 201r-v	Azige	Caparroso	1:0.6:0.3	Water and white wine; 6 days, RT Heated ca. 60 °C		Partidas broken	Dilute	No eches la tierra Don’t pour the dirt		2.14	2 ± 1	19.97; 1.03; − 4.80
Madrid Ep. 3 fol.192r-v	Caparrosa	n.a	1:1:1	White wine; 9 days, RT		Quebrantadas crushed	n.a	n.a	no	1.95	0.33 ± 0.04	27.26; 1.40; − 5.80

^aNames given in the original recipes
^bThe ratio is represented in weight and was normalized for the gall mass; in the simple descriptive model commonly described in literature: “9 g/L gallic acid monohydrate; 40 g/L FeSO₄·7H₂O; 80 g/L gum Arabic: 1: 4,4:8,9″
^cStep 1, reference to filtration after extraction; Step 2 reference of a final filtration, after the addition of FeSO₄
^dIn italic the original term for the processing of galls, binder and iron salt, followed by its English translation
^eAverage value, please see “Experimental” section for more details; the reference proposed in literature, prepared with gallic acid, displays a concentration of 9 mg/mL