Project Description
The Domus Aurea pigment show
One of the incredible things about encaustic is the way the pigments show their tones and brightness.
These vivid and magic pigments already impressed painters like Raphael or Michelangelo when they first saw the wall paintings at the roman Villa “Domus Aurea” (69 A.C.) soon after it was accidentally discovered at the end of the 15th Century.
Renaissance painters where aware of the limitations of the color palette in background fresco painting, where using certain pigments like vermillion, minium, alizarin, titanium or Ivory black pigments in large areas was totally inadvisable, since they proved to be very unstable when in contact with the lime mortar.
Domus Aurea golden hall’s ceiling, Francisco de Holanda. 1537-1540 http://tendimag.com/2012/04/15/domus-aurea-o-sonho-enterrado/
They must have been totally shocked when they saw those roman wall paintings showing those magnificent and continuous backgrounds, they “discovered” the magic of wax as an extraordinary pigment binder. Leonardo had a try but I will talk about it sometime in another post.
Although not much has survived till modern times, we can have an idea of what the Domus Aurea was upon its discovery looking at some illustrations on travelers notes like the ones from the portuguese renaissance painter Francisco de Holanda.
This post is also available in: Spanish
Current thinking – backed up by scientific analysis – is that Roman wall paintings were executed in a mixture of fresco and secco techniques using organic binders (prob. egg and casein) but not employing encaustic/wax.
As a conservator I worked on these paintings in the Domus Aurea (or what was left of them !) and there was no indication that wax was used.
When wall paintings are freshly excavated they are extremely damp (often wet to touch and extremely soft) and their colors are extremely bright and saturated because they are wet. If they dry out (and if they are underground, like in the domus aurea this may take years, decades or never) they gradually whiten because this water inside them is saturated with lime which has been extracted from the lime plaster, and as the water evaporates it leaves the lime as a white film on the surface. The paintings also tend to powder as the lime acts as the binder for the painting, and it has been dissolved and extracted by the water.
The misunderstanding about encaustic technique arose as in the (17th?), 18th and 19th centuries the people digging up the paintings used to coat them with wax (1) to maintain the bright colors (2) to stop/consolidate the paintings powdering . In the short term this worked but in the long term it was catastrophic, but at the time they had few alternative materials, and wax does work often for up to 20 or 30 years. Afterwards, unfortunately, it destroys the paintings, as we can see at Herculaneum (where I am also working) where we have well documented use of wax to preserve the paintings in the 20th century (1920-1960), and these are now in disastrous condition..
Thank you Mark! I will update the post with your comments.