Volume 6, Number 1, Jan. 1984, pp.11-12

Cyclotron Analysis of the Gutenberg Bible

Thomas Cahill, a physicist from U.C. Davis lectured at Caltech on the cyclotron analysis of Gutenberg Bible Old and New Testament inks, paper and parchment pages. The Bible studied was lent to Davis for two days from the Doheny collection.

The Berkeley 16 cyclotron accelerator was used. "Proton induced x-rays" were analyzed to differentiate any elements in or on the sample. The beam of the cyclotron is nondestructive and may be set to 1/3 millimeter. The radiation was so low that the librarian could hold the sample on the platform while it was being analyzed. The pulse of the beam could be reduced and then turned on as needed. Data was available in 30 seconds. It was therefore easy to reanalyze material if there were problems with the data. Approximately 1,000 analyses were done on the Gutenberg Bible.

Gutenberg's own inks were so distinctive in copper to lead ratio, that it can be determined when he left the printing project (due to financial difficulties) and took his inks with him. The second printing was not done with Gutenberg inks. Inks were made in batches and their composition changed with successive mixtures. It probably took 3 years to print the Bible using 6 to 15 batches of ink. In 1452 the inks Gutenberg used contained cooked copper lead oxide for blackness. There is almost no carbon in the ink. His sharp black ink has not turned brown with age. The thick consistency of the ink allowed it to stick to the movable metal type. The blue rubric was an azurite of copper ore and the red, still used in Gutenberg's time, was a vermilion of mercuric sulfide.

It was determined that the paper and vellum pages were printed at the same time because the inks used were consistent. It appears that pages were not printed recto and verso consecutively as the ink does change dramatically from front to back.

This information was submitted by Carol Young Verheyen, Manuscript Conservation Lab, Huntington Library. For further information please see The Newberry Newsletter, No.13, Spring/Summer 1983.

additional keywords: pigment analysis, vermillion