Artists, especially oil painters, love to talk shop.
Nothing is perhaps more controversial as the discussion of the ‘proper’ medium. It is often seen as the ‘secret’ ingredient’ in achieving the quality of the Old Masters. A good painter needs quality materials to express himself/herself properly. However, no medium is an elixir for creating a good painting.
The purpose of any oil painting medium is to adjust the handling properties of the paints to achieve specific effects. It is an important element that works in unison with the proper paints, ground, brushes, environment, etc. The alteration of one of these ingredients can negate the beneficial properties of the others. Only through experience and experimentation does a properly skilled painter arrive at a satisfactory result.
Most research into oil painting mediums, past and present, is focused on recreating the recipes used by the Old Masters of the 17th century. Their common denominator is that they are of a oleoresinous nature, meaning that they consist of a drying oil and a resin varnish. The genesis of this idea is found in the DeMayrne manuscript and is being confirmed with recent restoration documents.
I have studied and experimented in depth with Megilp. There are lots of different methods of preparing the oils and varnishes. Over the last 10 years I have tried many different recipes that I discovered in different written sources from the 17th century and after. In the end I found that properly cleaned cold pressed oil and a limited cooking with litharge produced the best drying oil. The best varnish should also be aged at least 6 months. The resulting medium is a blond gel. This is fundamentally different in philosophy than Maroger with its ‘black oil.’
As a medium, the version of Megilp that I have come up with functions quite well. Adapted for portraiture, it has good handling properties. It stays workable for several hours before setting up(perfect for those working from life). It dries completely overnight(with the proper pigments and ground). Certain painters are enamored with the fact that it is a ‘thixotropic’ gel. That aspect is certainly ‘cool’ but has little relevance with practicalities of good oil painting. Good impastos are not achieved with gel mediums. One disadvantage of this megilp is that it has limited fusion window for blurring(as opposed to a medium with a balsam).
Here are images of paintings that I did with my version of the Megilp about 15 years ago. They were both painted on lead primed linen that I prepared myself and a hand ground limited palette of historical pigments. Neither picture has been varnished. The Study of Florence was painted in 4-6 sittings. She has been constantly displayed(exposed to light) and never removed from the stretchers.
My Self Portrait study was painted in a couple of sessions(never completed) and subsequently removed from the stretchers and rolled. Once a year I unroll the painting to check its condition. As you can see the darks have sunk in but there is no yellowing or cracking in the picture film.