Analysis

Analysis of Red Pigments at the Drew University Special Collections

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Introduction

There are multiple scientific methods used in the art historical world to analyze artwork beyond what is visible to the naked eye. Two non-invasive methods used to study the chemical composition of paint pigments are visible spectroscopy and infrared reflectography. With the aid of Dr. Hinrichs, our group used both methods to collect qualitative data of multiple red pigment samples  taken from various materials owned by the Drew University Archives Special Collections. 

Methods

  Visible spectroscopy measures subtractive color through the refraction of light, on the visible light scale, as it bounces off of the pigment. This method was performed by Dr. Hinrichs and uses the platform OceanView. This method is ideal for our purposes as it is completely non-invasive; it does not require any contact with the materials. 

Infrared reflectography analyzes the pigment on the non-visible light spectrum and is used to detect reflected light. This method is also non-invasive but is more accurate than the visible spectroscopy; it requires direct contact and a very light pressure to be applied to  the manuscript.

Manuscripts

The first item we tested is Nicholas Culpeper’s Complete Herbal Guide, published in Great Britain in 1823. The volume includes illustrations that are hand colored. We tested two images, a wild poppy and hautboys (wild strawberries). Both illustrations use a very similar vibrant red pigment.  We believe this red pigment is material is our strongest hunch to have used cochineal carmine or kermes carmine because of the visual qualities and the publication date.  The volume was created before the invention of synthetic red pigments and at this time carmine would have been widely available. In the future we plan on testing various pigments as cochineal is also used as a base for other hues such as orange and purple. 

We then tested an Indenture (1756) which featured a faded red pigment in the detailed border and a bright red wax seal. The indenture is folded so it would presumably be protected from light and the fading may be a result of being put on display. 

We also tested a small Coptic Manuscript (1600s) with an elaborately painted bird-like mammal with vibrant colors. It is unlikely that this manuscript features cochineal carmine because of the date, but it is likely a kermes carmine or a plant based dye from the geographic region where the manuscript was created.  The exact region is not yet confirmed. 

We then tested three scrolls: a small scroll from the 1500s, medium sized scroll from the 1600s, and large scroll from the 1500s.  Each of the scrolls includes a translucent red pigment in the decorative borders or to highlight certain text passages. The red pigment is brown-toned, presumably faded from time and exposure to natural light.  It is unlikely that the scrolls use cochineal carmine due to the date and region of origin. Although there is no confirmed region of origin for each of the scrolls, they are not from the Americas and thus the use of cochineal carmine can be completely ruled out for the two manuscripts from the 1500s. 

Following the analysis of the scrolls, we chose to analyze two french books of hours from the mid fifteenth century.  There is a smaller one (1440) and a larger one (1460). We took a particular interest in the two manuscripts which include a small painting that resembles the prickly pear cactus that is the host for the cochineal carmine insects. Although cochineal carmine did not reach France until the 17th century it is possible that they had knowledge of the practice and we are curious to seek a correlation between the painting and pigment. If not cochineal carmine, it is likely that the painting has a kermes carmine base as that may have been the most lavish pigment available.

Perhaps of most interest is the analysis of the red pigments in Drew’s copy of the Nuremberg Chronicle. Although printed in the late 15th century, the exact date of the hand coloring is not known.  There are two very prominent reds in the manuscript, one brighter and warmer, the other cooler and darker. Both reds are well preserved and do not appear to have faded. The final manuscript we analyzed is Drew’s copy of the Shahnama. We tested two red pigments.  One is on the painted wooden cover and the second is used in the illustrations. We also tested a blue pigment as requested by Professor Rita Keane for her groups’ DHSI project on the Shahnama.  This copy of the Shahnama was likely painted in Shiraz, Iran during the 15th century thus the red pigment will not be cochineal carmine. 

Results

The first round of testing did not yield successful results due to the fluorescent overhead light source. Due to constraints on time, we retested only the Nicholas Culpeper’s Complete Herbal Guide (1823) from Great Britain as it was the object most likely to use cochineal. For this second testing session, no overhead fluorescent lights were used. Instead, a small and direct light source attached to the visible spectroscopy equipment was used. This time, we took samples from two different yet prominent red pigments in the manuscript. The first was a bright red used in the poppy illustration and the second was a fuschia color present in an illustration of wild peonies.  The second test using visible spectroscopy and the first tests using  infrared reflectography were successful. Both the visible and infrared tests of the red poppy are consistent with published results for cochineal carmine.