The Flemish method or Flemish technique refers to the likes of Jan van Eyck who were either inventors or early adopters of oil painting. The Flemish painters began painting in the Spanish low-country province Flandern (nowadays divided up into the Netherlands and Belgium). As a little red herring, the Flemish in Belgium speak a kind of Dutch, and the Dutch arguably speak a kind of Flemish. Either way, Flemish painting refers to both Dutch and Belgian heritage. It is not an umbrella term that makes immediate sense today, but saying Dutch-Belgian painting is more long-winded.
With some sweeping generalisations, and some oversimplification, the old flemish masters built up their oil paintings in layers.
A lot of scholars have since attempted to document the technique. At times they have made it sound more complicated, containing more layers, than laboratory analyses have later revealed.
Today you can replicate the technique with oils. However, with some imagination you can also paint Flemish with modern acrylics. In many cases acrylic colours have adopted the pigment names used in old-master oil painting. Retarders can slow down the rapid drying time of acrylic to match or surpass oil, and glazing medium can in effect do what linseed oil does to make semi-tranparency without pigments breaking up.
White primer on panel or canvas. In the past this was a mix of calcium sulphite, calcium carbonate with rabbit-skin glue. Today we have acrylic Gesso. Most painting canvasses are primed or gessoed, so in effect you can skip this and move onto layer 2.
The paper sketch is transferred to the painting medium and firmed up with graphite, coal or black ink. Some debate whether a pencil can be used as some claim that it pencil lines work their way through the following layers after applying a varnishing coat. To save yourself grief – or if in any doubt – make a test strip somewhere before embarking on your next masterpiece.
A mid-tone wash is applied. It has a name borrowed from Italian fresco- and tempura painting called Imprimatura. Here watered down Burnt Umber and/or Yellow Ochre does the job remarkably well.
Umber painting of all shadows. Some also apply highlights in white here, though others add highlights only at the very last layer. Either way highlights tend to be adjusted in the last layer in any case.
Penumbra and Verdaccio. Again Italian terms for painting This time it is with raw Umber and Yelow ochre. Verd(Italian for green)-accio is monochromatic almost moonlit painting of the finished composition before colours are being applied.
The Colour layer. This is like the other maybe a number of layers and semi-transparent colour glazes or interleaving clear glazes.
Highlights and touching up of details.