In the broadcast of 1-9-2016 o f the Avro / TROS, Old Masters, Girl with a Pearl Earring, intrigued me the protein varnish. It was used to see if craquelé of the original was done with protein. I went looking for more information about this and varnishes in general.
Below is an article published in the art magazine -Origine – (nr. 4 – 2011)
I found it on the website of http://www.schilderijrestauratie.info/content/2011/11/publicaties–Het-vernis. Unfortunately, there was nothing to be found in the aforementioned art magazine. Because the interesting information I want to put it right like on my blog. While reading, I see a lot of similarities with what is in the book of Mr. S. Grebber from 1840. I myself made in the early nineties dammar varnish from a recipe from a book containing centuries-old recipes. I did damar lumps in a piece of an old pantyhose (to let the impurities coming out of the varnish) and then did it in a pot filled with turpentine. This you should leave until the lumps are completely dissolved. Then remove the piece of the pantyhose with the unwanted impurities. This varnish is still gorgeous and certainly will not be discolored after a long time.
See here the said article:
“After all the attention to things that occur on the back of the painting it is time to move the time to the front. First, we often apply varnish there. Many paintings are finished with a layer of varnish, a transparent, basically colorless layer on top of the paint.
This varnish gives the painting depth, saturates the colors and protects against contamination. The varnish is composed of a resin, dissolved in a solvent.
After application, the solvent evaporates, and there remains – if it is correctly done-a thin and uniform film behind.
If too thick, varnish layer walk brushstrokes full thus loses the painting structure, and moreover easily glare occur.
As a resin a natural resin or a synthetic resin can be used, each with its own advantages and disadvantages.
Until the 15th century there are probably used mainly oil varnishes, it consisted of a drying oil, containing dissolved resins with some exotic names as olibanum, sandarac, mastic or amber. This varnish had a fairly dark brownish yellow color and became darker after drying still pretty after.
Occasionally painters have also used protein from chicken eggs as varnish – in several paintings by Vincent van Gogh we found, for example protein – sometimes out of sheer poverty, sometimes intended as a quick temporary layer. Whatever the reason may have been, well it is not, protein is insoluble after prolonged operation.
We can see from historical sources that varnishes are used from the 16th century with a volatile instead of a drying oil, including turpentine oil or nailing. Also alcohol varnishes did occur, such as rosin dissolved in alcohol.
In the course of time turpentine is increasingly used in dissolved resin, nowadays it is mainly dammar, mastic and synthetic resin varnish.
In the 19th century colored varnishes were used regularly, especially as an imitation of the golden tone of the old masters. (This golden tone was actually especially strong yellowed varnish) Coloured varnish is a way to create a certain unity in the painting, but is also sometimes used to cover wear and tear, or a suggestion of aging. In 20th century ever more value on a mat appearance of the painting was appreciated by artists , therefore, they were often not varnished. For example, a matte surface has a clear relationship with color theories of the Impressionists.
In particular, the varnishes from natural resins discolor to a greater or lesser extent. Incidentally, the discoloration worse by pollution here on marketing – smoking, cooking and firing in short. A highly yellowed varnish will cover all the subtle gradations in color, sometimes even completely change the color impression, eliminate all colors.
By evaporation of certain components, and influences from the outside varnish is inelastic in the course of time and brittle, there may be arise a still finer becoming verniscraquelé, and sometimes are cracks so close together that the varnish there is opaque, and the painting at these places can hardly be seen and appears whitish or cloudy. We speak of blind beaten varnish. At high humidity, this phenomenon can occur quickly, even when flooding immediately.
The need for cleaning / varnish removal then presents itself. Cleaning paintings sounds rather simple, almost domestic, but is nowhere near. It is, therefore, a good apart to be fitted between cleaning of the surface of the painting, and removal of the varnish. In the surface cleaning, the dirt is removed that has deposited in the course of time without affecting the varnish.
There are thick books written about the removal of varnish, advantages and disadvantages, technology and ethics. General rules are simply not giving each painting requires its own approach. In theory, the solvents used in varnish removal can damage the paint, making varnish removal in both technical and ethical terms a delicate matter where the necessary risks are applicable. There are unfortunately also many paintings who have been severely damaged due to improper cleaning.
From old records can be seen that paintings are be cleaned about every fifty years. I do not believe that for example paintings from the 17th century can not be found who are never cleaned.
One can imagine that it is precisely because the risks would be the time between cleanings for as long as possible is good, what is the reason for a lot of research into alternatives to the rather rapid yellowing natural resins with slower yellowing or better -no not yellowing varnish – will require cleaning less often. It is, therefore, looked at various possibilities, inter alia, addition of agents that block the ultraviolet part of daylight (this is the yellowing-causing part of the spectrum), and also synthetic resins that are considerably more stable than the natural resins find more and more application. There are also promising developments going on around the use of laser beams to remove varnish.
In the last century are indeed still ongoing fierce debate over whether a painting actually be well cleaned if, it could go to an original varnish and colored deliberately example. Moreover, the question is – what the artist had in mind? – A problem we can not ignore. Well known is the heated debate surrounding the cleaning of the Sistine Chapel, where the New York professor James Beck even spoke of a Chernobyl of art history. “
Another interesting website is: http://www.schilderijen-site.nl/encyclopedie/vernis/