I once painted an illuminated image on vellum, mostly in ink and gouache, but with a small area in egg tempera. Within a season the skin had warped, the tempera section had cracked and, in parts, delaminated (image attached, in raking light).KS ET on Vellum.jpeg The pigment involved in the delaminated area – genuine lapis lazuli – no doubt (due to large particle size and rigidity) exacerbated the inherent problem of an inflexible medium on top of a hygroscopic, moving support.
1. Medieval manuscripts are often said to be painted in “tempera”. How many are actually “egg tempera” versus simply a water-based “tempera paint” (gouache)? Is the same, somewhat confusing terminology that is seen in early Egyptian art (i.e. many images labeld “tempera” are not egg tempera) applied to manuscript illumination?
2. If manuscript illuminations are, in fact, egg tempera, how have them been preserved? Were they thinnly painted? Is the binding of a manuscript enough to keep them stable? Or, in fact, have egg tempera illuminations suffered more than images done in goauche or watercolor?
3. Any thoughts on adhering animal skins to rigid substrates? The facts of egg tempera (a high PVC paint that gets more brittle with age) combined with practical experience tells me animal skin supports and tempera are a problematic combination. Given how water-loving and strong animal skins are, would adhering them to a rigid support resolve the problem? Or exacerbate it (since skins and wood expand/contract at different rates = lots of stress in the artwork)? If not on a wood support, how about vellum on other substrates (paperboard, ACM, plastic)?
Any thoughts on the above are most welcome! Thanks, Koo Schadler
Hello,
This question was directed to the egg tempera moderator who initially failed to answer because questioner and moderator are one and the same (me). So, I did more research and wrote to several museums for information, which proved helpful. The updates to my thoughts on ET and illuminated manuscripts are posted below (for anyone still puzzling over an answer). Additional comments are, of course, welcome.
Koo Schadler
EGG TEMPERA ON PARCHMENT/VELLUM[1]
Medieval manuscripts are often said to be painted in tempera. It’s uncertain how many are actually egg yolk tempera, or are a generic “tempera paint” (a term used by museum to denote many types of water-based mediums). When the binder in a manuscript is precisely identified, it’s most often “opaque watercolor”, i.e. gouache (gum Arabic), glair (egg white), or distemper (animal glue).[2] There is also a degree of mixed mediums in manuscripts; some illuminators used different binders, depending on individual expertise (i.e. artists who were also panel painters, already familiar with egg tempera, more often incorporated it into a text) or perhaps on visual goals (i.e. amount of saturation or shine in a color).[3]
Regardless of the history (seemingly limited) of egg tempera on parchment and vellum, contemporary practitioners should note certain inherent constraints. Animal skins are extremely hygroscopic (water-loving); they really want to move with changes in humidity, and do so quickly. This is true even when attached to a rigid support; the expansion and contraction rates of wood and animal skin are very different and, depending on how the individual strengths of each material compete with one another, stresses can occur that deform or crack the paint, skin, or even wood panel (i.e. a thick vellum attached with strong adhesive can potentially deform a low density fiberboard). Instead, to impart some rigidity to animal skin, it’s best to bind it within a manuscript, as was traditionally done. Binding accounts, in part, for the excellent condition of many medieval texts; the format kept images secure and less susceptible to light, dust and humidity.
Given the inevitable challenges of a brittle medium atop a moving support, when painting atop animal skin it’s important to paint thinly (more like watercolor), in just one or a few layers. Small particle size pigments hold up better than large particle sizes (which are less flexible). Proper framing, and keeping an image in a stable environment (consistent relative humidity of about 50%) are also helpful. Applying a ground is not necessary when painting on parchment; animal skins are naturally porous and essentially the same glue used in traditional gesso.
[1] Parchment is a general term for animal skin – usually calf, goat, or sheep – prepared for writing or illustration. Vellum (French for veau, or veal) refers specifically to calfskin parchment and generally has fewer natural imperfections than parchment.
[2] Glair, made from egg white, is even more brittle than egg tempera. However it was applied very thinly; and, as noted, the manuscript format countered some of the inherent challenge of a brittle medium.
[3] The Fitzwilliam Museum, Cambridge, England (www.fitzmuseum.cam.ac.uk/illuminated/manuscript) has an excellent website devoted to illuminated manuscripts, with descriptions of materials and methods used in each manuscript. When I asked them about the presence of yolk binder in manuscripts, they replied, “Research is continuing, and the presence of lipid binders (i.e. containing actual egg yolk, which characterizes ‘real’ egg tempera, as opposed to simply egg white) is being noted in more manuscripts. [Egg tempera] is not ‘standard practice’, but a choice made by illuminators with excellent mastery of their materials and their intended effects. Most medieval and Renaissance manuscripts were probably painted mainly with gum Arabic or egg glair.” The museum recommended the following site, with many short but ‘illuminating’ videos: www.bl.uk/medieval-english-french-manuscripts/videos/
I also was sent this reference by a fellow painter: “…[the manuscript]… had their central figures painted in egg yolk tempera…This was an unexpected find because the most widely used paint binding media for miniature paintings on parchment were reported not to be egg yolk tempera but rather protein-based media (animal skin glue and egg white) or polysaccharide-based media (such as gums).” F. Gabrieli1, K. A. Dooley, M. Facini, J. K. Delaney. Near-UV to mid-IR reflectance imaging spectroscopy of paintings on the macroscale – Scientific Figure on ResearchGate. Science Advances, p 1-10.
Hello,
This question was directed to the egg tempera moderator who initially failed to answer because questioner and moderator are one and the same (me). So, I did more research and wrote to several museums for information, which proved helpful. The updates to my thoughts on ET and illuminated manuscripts are posted below (for anyone still puzzling over an answer). Additional comments are, of course, welcome.
Koo Schadler
EGG TEMPERA ON PARCHMENT/VELLUM[1]
Medieval manuscripts are often said to be painted in tempera. It’s uncertain how many are actually egg yolk tempera, or are a generic “tempera paint” (a term used by museum to denote many types of water-based mediums). When the binder in a manuscript is precisely identified, it’s most often “opaque watercolor”, i.e. gouache (gum Arabic), glair (egg white), or distemper (animal glue).[2] There is also a degree of mixed mediums in manuscripts; some illuminators used different binders, depending on individual expertise (i.e. artists who were also panel painters, already familiar with egg tempera, more often incorporated it into a text) or perhaps on visual goals (i.e. amount of saturation or shine in a color).[3]
Regardless of the history (seemingly limited) of egg tempera on parchment and vellum, contemporary practitioners should note certain inherent constraints. Animal skins are extremely hygroscopic (water-loving); they really want to move with changes in humidity, and do so quickly. This is true even when attached to a rigid support; the expansion and contraction rates of wood and animal skin are very different and, depending on how the individual strengths of each material compete with one another, stresses can occur that deform or crack the paint, skin, or even wood panel (i.e. a thick vellum attached with strong adhesive can potentially deform a low density fiberboard). Instead, to impart some rigidity to animal skin, it’s best to bind it within a manuscript, as was traditionally done. Binding accounts, in part, for the excellent condition of many medieval texts; the format kept images secure and less susceptible to light, dust and humidity.
Given the inevitable challenges of a brittle medium atop a moving support, when painting atop animal skin it’s important to paint thinly (more like watercolor), in just one or a few layers. Small particle size pigments hold up better than large particle sizes (which are less flexible). Proper framing, and keeping an image in a stable environment (consistent relative humidity of about 50%) are also helpful. Applying a ground is not necessary when painting on parchment; animal skins are naturally porous and essentially the same glue used in traditional gesso.
[1] Parchment is a general term for animal skin – usually calf, goat, or sheep – prepared for writing or illustration. Vellum (French for veau, or veal) refers specifically to calfskin parchment and generally has fewer natural imperfections than parchment.
[2] Glair, made from egg white, is even more brittle than egg tempera. However it was applied very thinly; and, as noted, the manuscript format countered some of the inherent challenge of a brittle medium.
[3] The Fitzwilliam Museum, Cambridge, England (www.fitzmuseum.cam.ac.uk/illuminated/manuscript) has an excellent website devoted to illuminated manuscripts, with descriptions of materials and methods used in each manuscript. When I asked them about the presence of yolk binder in manuscripts, they replied, “Research is continuing, and the presence of lipid binders (i.e. containing actual egg yolk, which characterizes ‘real’ egg tempera, as opposed to simply egg white) is being noted in more manuscripts. [Egg tempera] is not ‘standard practice’, but a choice made by illuminators with excellent mastery of their materials and their intended effects. Most medieval and Renaissance manuscripts were probably painted mainly with gum Arabic or egg glair.” The museum recommended the following site, with many short but ‘illuminating’ videos: www.bl.uk/medieval-english-french-manuscripts/videos/
I also was sent this reference by a fellow painter: “…[the manuscript]… had their central figures painted in egg yolk tempera…This was an unexpected find because the most widely used paint binding media for miniature paintings on parchment were reported not to be egg yolk tempera but rather protein-based media (animal skin glue and egg white) or polysaccharide-based media (such as gums).” F. Gabrieli1, K. A. Dooley, M. Facini, J. K. Delaney. Near-UV to mid-IR reflectance imaging spectroscopy of paintings on the macroscale – Scientific Figure on ResearchGate. Science Advances, p 1-10.
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