Techniques of Past Masters

"Perfection can only be acquired through practice, as laziness never produced anything of value." -- De La Fontaine

Philosophy of Drawing from 17th c. Spain

Art theoretician Vicente Carducho (1576 - 1638) wrote Dialogos de la Pintura which promoted the idealising neo-platonic artistic theory from central Italian tradition, while at the same time criticising the direct painting methods of Caravaggio and Velazquez.

According to Carducho, drawing takes place internally (disegno interno - the idea) before it can be expressed outwardly (disengo esterno). In this process of expression, the student of drawing will progress through three stages of artistic development.

1.) Copying: An artist will copy master drawings and sculpture, or copy from nature, including from a live model, "without taking into account more than its imitation." To Carducho, this was the least estimable type of drawing and the basis for much of his criticism of direct painters. Copying nature is the training tool that allows disegno interno to become designo esterno, but it is not design in and of itself.

To Carducho, the benefit came in studying nature -- this correct activity, which consists of observing, and selecting from nature -- essentially inventing an improved nature -- contrasts with what he calls 'direct copying of what one sees before one's eyes' -- naturalism. The necessity for this selectivity comes from the fact that nature is always moving and always seen from various angles, panoramic, and through time. But the painting is still -- a single image from a single viewpoint within a limited frame of reference. The struggle of modernism to deal with these limitations led to cubism.

2.) Invention: Once a draftsman has mastered the ability to reproduce the object before him, he begins to "delineate upon some surface, a subject from memory or from a book...or from [his] imagination (fantasia), which is commonly called inventar or to debujar con fantasia" in order to "bring to light ideas from [the artists'] understanding which were conceived by means of reason, discourse, observations and precepts."
The key to invention is knowledge, practical and theoretical/philosophical.

3.) Perfection: This is where the artist takes the idea sketch and "nurtures and cares for this idea with practical [skill], scientific precepts and perspective, until its final perfection is achieved...This is the...most difficult and estimable kind of drawing, because the [sketch] could have been managed by either force of genius or by chance, but this can only be accomplished through much work, study and science." It is only with the perfection of design that one is ready to transfer his drawing to canvas.

Velazquez's teacher and father-in-law, Francisco Pacheco, wrote in 1638:

It is certain that the activity of making sketches, drawings, and cartoons directly belongs to painters who have achieved the third and final grade of their art; they are more obliged to invent new things... They prepare themselves to paint either by counsel from learned persons or by reading books, and thus forming their ideas, they fabricate a whole from parts. Then they draw the first rough ideas of the movements and actions required for the lively expression of the subject to be painted. From three or four studies, they choose one to be used (either by their own taste or by the judgement of learned men)

Yet still he relies on copying as the foundation of his creations:

I keep to nature for everything; if everything could be taken from nature, not only the heads, nudes, hands and feet, but [also] the would be much better.

It was advised by Le Blond de la Tour of France that a child should begin to study drawing at the age of ten to twelve after having learned to read and write. He should begin as an apprentice to a master, and then progress to the Academy to study from the live model.

De Piles suggested that one should begin with learning to draw heads; for he considered that if you could draw a head you could draw a flower, but not vice versa. He advised drawing on a large scale and beginning from nature.

-- Massing

To check your drawing or painting, the following advice is given by Du Fresnoy in regards to the use of a mirror.

The Painter must have a principal Respect to the Masses, and the Effect of the whole together. The Looking Glass distances the Objects, and by consequence gives us onely to see the Masses, in which all the little parts are confounded.

Since the Mirror is the rule and Master of all Painters, as showing them their faults by distancing the Objects, we may conclude that the Picture which makes not a good effect at a distance cannot be well done; and a Painter must never finish his Picture, before he has examin'd it at home some reasonable distance, or with a Looking Glass, whether the Masses of the Lights and Shadows, and the Bodies of the Colours be well distributed. Georgione and Correggio have made use of this method.

Leonardo's view is reflected in the following two excerpts:
"Those who are in love with practice without knowledge are like the sailor who gets into a ship without rudder or compass and who never can be certain where he is going. Practice must always be founded on sound theory, and to this Perspective is the guide and the gate way..."
"The painter who draws merely by practice and by eye, without any reason, is like a mirror which copies everything placed in front of it without knowing about them."

Basic Practices In Painting

Brushes used by the Flemish were made of hog's hair bristle or of squirrel hair for detailing.

The Flemish painters painted thinly on a bright white ground on wood panel sealed to make it non-absorbent. A drawing was transferred after careful studies had been done. Then a general tint was applied (imprimatura), through which the priming is visible, in pale flesh tone, brown, or even gray. [Rubens painted on a light gray.] This was to assist the middle tints of the picture and never excluded the still lighter priming.  Shadows were painted first as transparent glazes that allowed the light to pass through and reflect off of the white ground. Then lights were built up gradually from there. In this thin, transparent method of painting, grounds of Verdigris and Umber are discouraged because they kill the colors that are applied over them, the Flemish tending always towards warm shadows.

"The painting was executed as much as possible at once, and therefore, occasionally, in portions at a time. This last system was, by degrees, so far departed from, that the design, especially when of large dimensions, was dead colored from a finished sketch, so as to avoid alterations in the more complete work." Eastlake p.484
In the carnation of the work, colors were applied in one coat with tints mixed to the local hues required.

"Later painters employed a dusky priming, serving as a middle tint for the shadows rather than the lights." Color: white lead, black, red ochre, and sometimes a little umber.

Linseed oil was still made clear and drying by the use of calcined bones. A vehicle was mixed using a hard resin like mastic or amber mixed 1:3 with linseed oil. "The use of oleo-resinous vehicles...rendered a final varnish ...needless." Diluted with an essential oil, "the consistency of the vehicle itself, except when employed for rich shadows, was at all times such as to be compatible with the sharpest execution." Drying was further increased by addition of metallic oxides.

When a thinner vehicle was used, the work was coated with an essential oil varnish. In Italy liquid resin or balsam was dissolved or diluted in spirit of turpentine or other volatile oil. It is written that the best varnish is pure resin of fir (olio d'abezzo) warmed gently and mixed with a greater portion of rectified clear petroleum (naptha) and applied warm to a warm surface, very thinly with a brush. It is transparent, has a good sheen (like fresh paint) and does not yellow over time. Also, it dries very quickly, not trapping dust. But the very thin essential oil varnish alone was not enough to protect from moisture in the damp North where mastic was added to increase body and eventually completely replaced the liquid resin of the silver fir (Abies pectinata or taxifolia) or larch (Venetian turpentine). Works that needed to be especially protected from humidity or moisture were always varnished with an oleo-resinous mixture such as linseed and mastic as in the vehicle described above.

"Among the technical improvements on the older process may be especially mentioned the preservation of transparency chiefly in the darker masses, the lights being loaded as required. The system of exhibiting the bright ground through the shadows still involved an adherence to the original method of defining the composition at first, and the solid painting of the lights opened the door to that freedom of execution which the works of the early masters (lacked)." [In the early school, even the lights were painted translucently to make use of the light ground.]

Painting Lights and Shadows

" regard to the lights: in them the colors may be loaded as much as may be thought requisite. They have substance: it is necessary, however, to keep them pure. This is effected by laying each tint in its place, and the various tints next to each other, so that, by a slight blending with the brush, they may be softened by passing one into the other without stirring them much. Afterwards you may return to this preparation, and give to it those decided touches which are always the distinctive marks of great masters." --Rubens

Van Mander, whose precepts are antecedent to the influence of Rubens, comments on the coloring of flesh in the highlights: "Let not your flesh colour freeze; let it not be too cold or purple, for a carnation which approaches the whiteness of linen cannot bloom with the signs of life. But vermilion makes it glow with a more fleshy hue. Endeavour to produce this warmth . . . . In painting peasants, shepherds, and mariners, spare not yellow ochre with your vermilion. . . . Be careful not to light up the flesh tints in either sex with too much white; no pure white is visible in the living subject."

The Flemish recommended that one not use black or white in shadows, as they deaden the quality, eliminating the desired glow of transparency which makes proper use of the white ground. Rubens stated, "be careful not to let white insinuate itself into (your shadows); it is the poison of a picture except in the lights; if white be once allowed to dull the perfect transparency and golden warmth of your shadows, your colouring will no longer be glowing, but heavy and gray."

"The Flemish...were careful to preserve transparency as much as possible in the darks; for, whatever be the nature of the color, internal light still exhibits its maximum of warmth."

Shadows should depict a uniformity of tone, a -- "simple unity of shade, as all were from a single palette spread." -- Du Fresnoy
Rubens general transparent shade fulfilled this rule.

"The purest colour in an opaque state and superficially light only, is less brilliant than the foulest mixture through which light shines." In Flemish works a thinner medium was used for the lights than the darks, so that, even in the lights, the white ground affected the color. "If those painters erred, it was in sometimes too literally carrying out this principle. Their lights are always transparent (mere white excepted) and their shadows sometimes want depth. This is in accordance with the effect of glass-staining, in which transparency may cease with darkness but never with light. The superior method of Rubens consisted in preserving transparency chiefly in his darks, and in contrasting their lucid depth with solid lights." Lights become more translucent with age, but darks deepen and lose detail and brilliance. So emphasize the translucence of shadows from the start.

And though Rubens warned against whites that cause opacity in the shadows, a dry white preparation underneath the rich darks is by no means prohibited; indeed it existed in the white ground. So if one creates form with white in the shadows, it can then be glazed with transparent color for a similar effect as that which makes use of the white ground. This was done by the Italians, who sometimes began a work in white and black, glazing them to the highest degree of warmth. Such was the practice of Tintoretto, and of Titian who, after painting his grisaille in lead white and carbon black, layered it with red and yellow ochre and cinnabar (vermilion) plus lead white in the lights. (see Reynolds observations below) And even Rubens used white to create reflected lights, so that his instructions must be understood within the particular method in which they were employed.

Observations and Practices of Sir Joshua Reynolds of England

"The Leda, in the Colonna Palace, by Corregio, is dead coloured white, and black or ultramarine in the shadows; and over that is scumbled, thinly and smooth, a warmer tint, I believe caput mortuum [ colcathar of vitriol ].

"...The Adonis of Titian, in the colonna Palace, is dead coloured white... the shadows in the light parts of a faint purple hue. That purple seems to be occasioned by blackish shadows under, and the colour scumbled over them."

Again: "Dead colour with white and black only; at the second sitting carnation (add colors to bring life to the form). [To wit, the Barocci in the Palace Albani, and Corregio in the Pamphili]

Reynolds, who scarcely ever left a light ground in the manner of Rubens, supplied its warmth, where he felt it to be desirable, with such colours.

General Recommendations on Painting Flesh Tones

While there were many recipes for painting skin tones, three common mixtures were generally used by De La Fontaine.

Layering for Normal Flesh Tones
lead white, yellow ochre, lake and brun rouge (burnt sienna)
2.) same, but more colour than white
3.) brun rouge, lake and umber.

Layering for Delicate Flesh Tone
lead white, vermilion and yellow ochre
2.) more ochre and vermilion than white
3.) more vermilion

Layering for the Flesh of a Country Person
umber, white and a little brun rouge and green earth
2.) lake, umber and brun rouge for the shadow tone

Paint Handling and Application

The Flemish practice of thin painting also had the benefit that "a picture with an even surface has the advantage of not being easily soiled." -- Hoogstraten

But he also learned from Rembrandt: "It is above all desirable that you should accustom yourself to a lively mode of handling, so as to smartly express the different planes or surfaces [of the object represented]; giving the drawing due emphasis, and the colouring, when it admits of it, a playful freedom without ever proceeding to polishing or blending: for this annihilates feeling, supplying nothing in its stead but a sleepy constraint, through which the legitimate breaking of colours is sacrificed. It is better to aim at softness with a well nourished brush, and, as Jordaens used to express it, 'gaily lay on the colour,' caring little for the even surface produced by blending; for, paint as thickly as you please, smoothness will, by subsequent operations, creep in of itself."

Northcote recorded the same sentiment from Reynolds.
"To preserve the colours fresh and clean in painting, it must be done by laying on more colour, and not by rubbing them in when they are once laid; and if it can be done, they should be laid just in their proper places at first, and not any more be touched, because the freshness of the colours is tarnished and lost in mixing."

These directions are given to solid painting, in which the effect of the colour is not calculated on the light ground underneath.

Hatching was considered a defect of the tempera process - too mechanical - "it is unpardonable in oil." The oil process was developed primarily to allow for a softening and blending of colors, therefore paint should either be blended to a polish, as in Van Eyck's works, or else it should be painted freely, like Rembrandt's.

In the 17th century, spontenaity of brushwork (painterliness) was much admired in the work of Velazquez and others of the "Venetian" school. The desire to simplify and select was promoted in literature and philosophy and applied to art. Gracian said, "Value quintessence above confused variety," and "That which is brief, if good, is good twice over." And according to the president of the French Academy, Jean-Baptiste Oudry (1666-1755), "the painting should be executed quickly and accurately, always keeping the details subordinated to the whole. Every brush stroke should be loaded with the precise colour."

Methods for constructing the paint layer
in order to counter discoloration.

- from the book Looking Through Paintings.

The sources show that painters expected that the discoloration of binding media and pigments could be combated by composing the paint layer systematically. seventeenth century texts reveal that the general practice was to divide the painting process into a number of phases. In the underpainting; known as the 'dead-colouring,' various aspects were roughly applied. these included the composition, the main division between light and shadow and also, according to various seventeenth century texts, a first impression of the colours. After the dead-colouring, the process was divided up into the following phases: the 'making up' where the depiction was further developed in colour and the 'retouching' where the final painterly details such as the highlights and deepest shadows were added. By deploying a particular system for the construction of the paint layers which involved applying the pigments in the 'right' way to the 'right' layer, the painter could exploit the advantages of the less colour-fast pigments while reducing the risk of discoloration.

Among the French the stages were listed as the sketch (l'esquisse), the build-up of paint layers (empater), and the finishing touches (et retoucher).

By predetermining the outlines in the preliminary drawings and painted sketch, one could avoid pentimento later on. The sketch was to be the final state, and no changes to the outlines should be made. If an alteration was necessary, several layers would have to be applied on top to cover the 'error.' By this time, the French were producing their sketch in color, not in monochrome as the earlier painters had. The first layer of paint into the forms was known as l'ebauche, and was to lay out the composition with colour as evenly as possible.

In the build-up it was important to follow the first layer sketch, laying in color in their respective places. "Jombert said that it was important to paint each area several times with the same colour or the ground would show through with time and 'kill' the colour." It was advised that the paint should be thickest in the flesh tones.

Most authors warned of the danger of 'muddying' the tones by repeated applications of colour [wet on wet]. Félibien counselled against tormenting the colours with the brush..., laying on the colour thickly in several layers in the flesh tones. De Piles and Dupuy du Grez also advised against over-working the colours; the painter should work methodically and cleanly so that they did not become muddy.
-- Messing

It was advised by most to apply paint directly onto paint, and not to add intermediary layers of oil, as they will yellow and discolor the work. But if the paint has sunken in, it can be oiled out with varnish, which was believed to be less likely than drying oil to yellow. Oudry stated that painting on varnish ruined the colours (by yellowing) and that Venetian turpentine and a little nut oil could be rubbed in to oil out a section. He warned that this was not sound practice, however, especially for white drapery or flesh tones, for the varnish would yellow and darken the skin tones. (though purified venetian turpentine will not yellow) "Sound practice was to paint onto paint, not onto varnish," especially resins.

Some artists recommended using less lightfast colors in the dead-colour and glazing over them with more lighfast color that would shield them, such as glazing ultramarine over indigo. But others, such as De Mayerne and Pacheco, advised using the best quality color throughout, fearing that poor colours in the underpainting would kill the others as they faded.

Since most of today's tube colors of lower lightfastness are also of high oil content, I tend to use them only in the top layers. I have begun to use more permanent colors underneath that will give sufficient color so that, should the top glazes fade, the painting can still stand. Frans Hals, Judith Leyster and Johannes Verspronck all used indigo in the top layer and combated its tendency to wash out or bleach by grinding it with little oil and painting it dark, even in highlights.

Pacheco suggested that a red vermilion under-painting would preserve an upper layer of pink paint that had been mixed from carmine and lead white. This was because, in the course of time, the vermilion's clear red could still glow through the discoloured layer. The vermilion also absorbed more of the light than a white ground so that the paint layer with carmine would be exposed to less reflected light. Willem van Aelst used a similar method in painting green leaves. The underpainting is done in ultramarine and white and glazed with verdigris. As the verdigris aged and turned golden brown, it visually mixed with the blue underpainting to maintain the look of green.

Greatest Causes of Discoloration in Oil Paintings
1.) drying oil that was not adequately purified.
The impurities coming to the surface or showing through the paint as it aged, causing the paint to darken and turn brown. Modern industrial purification processes have largely eliminated this problem.
2.) separation of oil from the pigment. This leaching of excess oil then makes yellowing more apparent. This was a greater problem in hand ground oil colors of the past, especially those of large partical size. Modern machine ground colors are generally finer and there is better dispersment of pigment within the binder, allowing the paint to be made with less oil. The ratio of pigment to oil will vary, however, between student grade and professional grade paints, and from pigment to pigment. Colors which appear to contain excess oil can be blotted on a paper towel before being used.
3.) top coat varnish which has aged, yellowed, and collected atmospheric dirt.
When removed for revarnishing, the underlying paintings are often found to be in very good condition.

The Case of Jan Van Huysum
Still Life Painter.

Jan Van Huysum painted on Mahogany panels primed with lead white oil priming, contrary to the older habit of using gypsum or chalk. Perhaps the use of oil priming on linen led to his use of it on panel. An analysis of one of his panels showed the first layer of ground to be lean lead. But the second was lead with "negligible amounts of aluminum, silicon, calcium, and iron."

Early in his career he used a dark ground, but later switched to a lighter ground, as we find with many artists. Coincidentally, his backgrounds also changed. Early on he painted dark interior walls behind his still lifes of flowers and fruit, often lit be a band of sunlight. But later he set his works outdoors or on a window sill beyond which one could see a bright, sun-filled garden with statuary, urns, and people.

Van Huysum executed a preliminary drawing and value study in washes of reddish brown paint (a mixture of lead white and red madder lake). He used sketchy, broad washes to determine the composition rather than to delineate specific objects.

The painting was executed in 1 to 3 layers of paint (usually 1 to 2), usually painted opaquely and directly over the compositional washes. He then glazed with red and yellow lakes. On one occasion he layered blue in 3 layers. Van Huysum used a number of new pigments of finer grain which allowed for his highly detailed style. One of these was Prussian Blue, which has a much finer particle size than Ultramarine. The details of his work are at times so intricate (such as a bird's feather in a nest) that it is believed he may have painted them with a single hair!

Van Huysum painted wet-in-wet, with a linseed oil binder for his colors -- no sign of other medium was identified. He worked systematically from the back of the scene to the front, following the underpainting. Because he combined flowers and fruit which had different growing seasons, he often took many months to paint a work while waiting for a particular flower to blossom, or fruit to become ripe. He therefore had to determine the composition in his mind, since he did not have all of the elements together at one time.

Though some of his yellow lake glazes have faded, his works have remained in remarkably good condition.

On Mediums and Varnishes Used.

The sharpness in Venetian pictures is "incompatible with the employment of a thick vehicle." But a thin vehicle demanded a final varnish. Essential oil varnish was chiefly composed of Venice Turpentine, a material which, when not carefully purified, is very apt to grow yellow.

One medium used by Rubens followed this recipe:
3 parts Venice Turpentine
2 parts Sun Thickened Walnut oil
1 part Mastic Varnish
with an added siccatif

(Today, one might freely create a similar recipe with Venice Turp., Sun-thickened linseed or Stand Oil, and Damar Varnish)

Due to the yellowing nature of oil and varnish and their effect upon highlights, the lights were given more force by comparison with darks. "The influence of the colour of the vehicle on the quantity and depth of shadow is, indeed, plainly to be traced in the general style of oil painting, as compared with tempera and other methods."

If a fresh painting turns yellow or brown, placing it several times in the sun or in open air will exhaust the exudations which cause the yellowing of the surface. when pictures are safe from further change, then removal from the sun will preserve them. "...their protection from the sun's rays, when there is no longer any 'superfluity of oil' to dissipate, is essential to their preservation."

Smith notes in his book the effects of light on a painting once dry:
Diffuse light - slow hardening, relatively little decomposition and some yellowing. (The ideal environment.)
Ultraviolet light - rapid hardening and embrittlement, followed by severe deterioration.
Sunshine - fairly rapid hardening with embrittlement and severe deterioration.
Darkness - slow softening and considerable yellowing.

Again, Eastlake gives a recipe for an essential oil varnish: 1 oz. of resin of Turpentine melted with 2 oz. of napthol of petroleum in a water-bath, taking care that nothing boils. This varnish never cracks, does not become opaque and displays your work perfectly.

'But Rubens states that resin of Turpentine "becomes arid, and is not proof against water. The best varnish, resisting water, is made with drying oil, much thickened in the sun on litharge, without boiling at all." An essential oil varnish worked well in the dry Italian climate, but without some admixture of oil, it is not durable in a humid climate.'

"...any varnish, whether composed of mastic, sandarac, or other resins, which cannot bear moisture without becoming white, and thereby spoiled, will bear it without injury if you add to your varnish a little drying oil bleached in the sun, in the mode before explained. This oil should be thinned (so as to be easily spread) with spike oil, which presently evaporates; thus the drying oil will preserve all the rest." -- M. Portman

Proportion = 1/2 oz. very drying linseed oil to 1 lb. of varnish.
Oil also prevents cracking. Another recipe gives 1:8 proportions.
This is for a final varnish only.

But the linseed oil must have been dried and purified. The drying resinifies it, making it a varnish in and of itself. The purification prevents yellowing. The small percentage added to varnish still allows for the removal of the varnish when it is aged.

Rubens preferred to use a drying oil vehicle that incorporated hard resin varnish in order to prevent the need for a final top-coat varnish in the damp north, where an essential-oil varnish failed to protect from moisture and adding oil caused any degree of yellowing. But if a varnish was needed, he would use this same oleo-resinous vehicle, thinned with essential oil for such purposes.

"There are as many different methods of painting as there are painters', some sketch lightly, others finish in one step (au premier coup), others sketch neatly and retouch after."

"Do not try to master many techniques; too much diversity leads to misunderstanding. After listening to the counsel of our masters we should choose the best method and learn to master it thoroughly."

-- La Blond de la Tour

History, Definitions, and Techniques | Drying Oils and Mediums
Resins and Varnishes | Pigments Past |Pigment Chemistry
Supports for Painting | Grounds on Canvas | Techniques of Past Masters
Discussion with National Gallery Conservator