Secrets of the Old Masters: Glazing and Scumbling (Part 2)
In Europe the method of glazing was perfected in the 14th through the 19th century. The majority of the artwork done by the masters featured glazing techniques. It was a very important traditional technique and every fine artist would utilize it to its full advantages. Glazing in oil painting is the technique of applying very thin transparent or semi-transparent layers of oil paint over the dry surface of a painting. Glazing is used to enhance, change or deepen the colours of the painting. The glaze is a transparent or semi transparent layer of paint which is thinly spread over the top of the dried oil paint surface.
Detail of Seven Sacraments Altarpiece (Painting) by artist Rogier van der Weyden, 1445-1450 located at Marlborough Fine Art.
When light penetrates through the top glazed layer it reflects from the surface of the layer underneath and bounces back so the viewer can see that layer.
As the transparent glaze has its own colour it changes the appearance of the lower layer, the colour of the painted surface becomes deeper and richer. Such reflected light through one or more transparent glazing layers can produce some light diffusion and glow. The glazing technique is a very laborious and time staking process however the results which it provides are not achievable by any other means in oil painting. The full benefits of glazing layers are achieved by oil painting, acrylic for example would not provide the same results. Not every oil paint is suited for glazing though, those paints that are transparent or semi-transparent are best suited for glazing. Opaque paints have strong covering properties and therefore can be used with caution if used at all for the purpose of glazing.
The glazing method is based on the ability of colours mixing optically and changing their appearance when two or more colours are applied. The knowledge of optical mixing of colours cannot be underestimated. When one colour is covered with another layer of transparent oil paint with a different colour the hue changes its appearance. This appearance is not achievable by any other means such as the physical mixing of the oil paints used. Very complex and deep colours can be achieved in this way. It takes some knowledge and experience to predict these results.
The glazing method is used for several purposes, it is used to change the chroma, value and hue of colours.
It can deepen the colour tones and visual depth of the painting and change the texture of the painting to a glossy surface, unite various colour patches in one harmonic range, soften off edges and contours.
Usually glaze layers are used to finish the painting. I like to use Kolinsky sable brushes for glazing fine details, such as eyebrows or hair strands. Kolinsky sable brushes are some of the highest in quality; they leave small traces of brush strokes and glide seamlessly unto the canvas. Walnut oil (which is the medium I use for glazing), has a low viscosity and the consistency is runny which allows me to create very thin feathery smooth strokes.
A collection of mediums I frequently use to enhance my oil paints; each of them yield unique results.
This is the stand oil I've mixed with oil paint, it offers a luxurious thick consistency that can appear glass-like.
Kolinsky sable brushes are highest in quality on the market; they leave very little trace of brush strokes and glide seamlessly unto the canvas. This specific type of Kolinsky brush is called the Winsor & Newton's Series 7 and theyère made from sable hair in rust-proof, seamless nickel plated ferrules with black polished handle which are well worth the investment.
Winsor & Newton's Liquin Fine Detail Medium allows me to paint in tiny details like hair strands and eyebrows. It speeds drying time and usually dries within a day.
When some of the masters would use glazing on top of the under-painting or dead layers, others would continue the painting with body colours before finishing it with glazing. White paints are not used for glazing purposes, that is why the glazing processes always goes from light to dark tones. Every glazing layer is applied after a previous layer is dried. Drying time depends on the thickness and type of oil paint as well as the oil medium used in the glaze. Usually paints are diluted in the mediums to increase the transparency of the glazing layer.
The glazing technique is often used for portraying the complexity of skin tones, human skin for example is not 100% opaque, so flesh and blood under the skin gives the complexity of the skin's colours.
Such skin effect rendering can be achieved by the glazing method, the great masters sometimes used cold colours for the under-painting of figurative artworks. Such coloured under-painting is often called the dead layer, when finishing portraits with warm glazing artists were able to mix optically cold and warm hues. This allowed them to get very realistic skin rendering otherwise not achievable by mixing paints on a palette. When multiple layers of glazing are used, the colour of each layer will contribute to the overall gamut of the painting surface.
A fine artist can use several glaze layers, the number of layers depends on a particular creative task as well as the personal preference of the artist. Every time a new glaze layer is applied the painted surface's appearances change. The pigments of the paints are not intermixed because the previous layer is dry before actually applying a new one. As for any multi-layered painting technique, the glazing method must be used according to the fat over lean rule to minimize cracking of the paintings surface, every new layer of paint needs to contain more oil or be fatter than the layer below.
One of the first masters who developed the oil painting with use of glazed layers was Jan van Eyck, this discovery gave a big advantage to painting over the old tempura method. With glazing it becomes possible to depict the smallest variations of colours and tone gradations which was the revolutionary method at the time. Never before did the world see such vibrant and defined colours produced by artists. Other artists of north renaissance like Rogier van der Weyden, Hugo van der Goes, and Pieter Bruegel the Elder were developing glazing methods even further.
Descent from the Cross (Detail) by Rogier van der Weyden (Flemish painter),1400-1464)
Virgin and Child,1460, by Rogier van der Weyden (Early Netherlandish painter).
From the Netherlands the glazing method was then passed on to Italian fine artists.
Detail of The Fall of the Rebel Angels (Painting) by Pieter Bruegel the Elder (Flemish Renaissance Artist), painted in 1562 with oil on panel. Currently exhibited at the Royal Museums of Fine Arts of Belgium in Brussels.
The Peasant Wedding by Pieter Bruegel the Elder, created in 1567. Currently exhibited at the Kunsthistorisches Museum in Vienna.
The Italian method was as follows:
After transferring a drawing unto the support, and outlining it with paints, it was glazed in several layers first in cold colours, then in warm colours, which were required. Sometimes the white ground of the canvas or board was covered with a thin flesh coloured imprimatura layer.
The painting method of the small Dutch picture of the 17th century often featured a cold grey background which was partially visible through the upper layers of glazing.
The old masters would always pay attention to the clarity of the glazed layers, thick impasto layers came into use at a much later time.
The Flemish fine artists of the 17th and 18th centuries were using red and brown grounds for their paintings. Michelangelo Merisi da Caravaggio (1573-1610)was one of the fine artists to use dark almost black grounds.
Judith Beheading Holofernes by Michelangelo Merisi da Caravaggio painted in 1598-1599, oil on canvas. Currently exhibited at the Galleria Nazionale d'Arte Antica at Palazzo Barberini in Rome.
Later on, academic painters were combining thick layers of body paint with upper layers of glazing.
Lights were painted in a thick opaque paint mix or sometimes in glazes over a white under-painting. Shadows were painting over neutral tones, such complicated painting methods, Italian term "Pentamenti" provides great flexibility and is based on the revealing of a painting or part of a painting that has been covered over by succeeding layers. The glazing technique is suitable for many genres of oil painting, however in portraiture it works particularly well because transparent glaze layers depict human skin realistically and believably. Glazes are also suited for cases when a colourful gamut of artwork needs to be united in a certain hue direction, for example a still life object may have many colours and all those colours visually divide this object, so to bring it together fine artists may apply one or several layers of glazing to unify the common shape of the object. Landscapes can also benefit from the glazing technique, for example a lake is painted so that its colour appears too cold, the fine artist may decided to cover the entire lake area in an orange yellowish glaze to make it look warmer and blend harmoniously with the entire scene. Covering areas in grey blue glazing will make an object look colder. When glazing, one would approach it in the same manner as painting in watercolour, the fine artist would start with a light area and work their way toward a dark area. Changing colours with glazes is a common approach in traditional oil painting, for example neutral grey can change its appearance to red, (when a transparent layer of red coloured paint is applied on top). The same neutral grey can go blue when covered with ultramarine blue coloured glaze.