Mössbauer study of iron gall inks on historical documents

Heritage Science

Table 1 Total areas of the Mössbauer spectra of the studied specimens

Document	Absorber thickness mg/cm²	Total area at RT	Iron content mg/g	Total area at 4.2 K	Iron content mg/g	Surface pH
Chancery MS total	545	0.038	3.6	0.112	6.0	4.2–3.9
Chancery MS paper only	240	0.0031	0.44	0.0029	0.50	4.8
Latin MS paper with ink	219	0.037	8.8	0.11	21	4.8
Latin MS paper only	386	0.0081	1.1	0.012	1.2	5.3
Cookbook total 53 pages	360	0.014	2.0	–	–	–
Cookbook total 121 layers	825	0.016	1.0	0.037	1.7	4.9
Cookbook paper only 88 layers	600	0.0017	0.15	0.0011	0.07	5.7

The iron contents were estimated from the intensities of the Mössbauer spectra as described in the text. The smaller values for the iron contents obtained from the RT spectra compared to those from the 4.2 K spectra are attributed to the decrease of the Lamb-Mössbauer factor with increasing temperature. In the last column the surface pH values of spots with ink and, for the papers only, of spots without ink are given