The Flemish method

There are sev­eral cur­rent paint­ing meth­ods whose prac­ti­tion­ers claim that they are work­ing just like early Flem­ish painters did. In the early 1400’s, Flem­ish and Nether­lan­dish painters (Jan van Eyck, Robert Campin, Rogier van der Wey­den, and so on) invented oil paint­ing as it is prac­ticed today. In the 19^th and early 20^th cen­turies, art his­to­ri­ans spent a lot of time spec­u­lat­ing about how the first oil painters prac­ticed their art. Unfor­tu­nately, they could only look at paint­ings and read old man­u­scripts. As it turns out, look­ing at paint­ings doesn’t tell you a whole lot about the meth­ods by which they were made. And the early oil painters didn’t, so far as we know, write down their valu­able trade secrets for schol­ars hun­dereds of years later to study.

So most of what you will see about “Flem­ish” paint­ing meth­ods, although some­times used by very skilled artists, is basi­cally what some 19^th cen­tury Ger­man aca­d­e­mics erro­neously thought North­ern Euro­pean paint­ing was. There is one school that alter­nates lay­ers of egg-oil emul­sion white with lay­ers of oil glazes in pri­mary col­ors. Another school calls for each paint­ing to be made in seven lay­ers, each of which dries for seven weeks (are we artists or numerologists?).

The rea­son why peo­ple are so fas­ci­nated by early Flem­ish paint­ings is that they are so remark­able. First, although they are very, very old, they are often in much bet­ter shape than oil paint­ings that are hun­dreds of years younger (many early 20^th cen­tury paint­ings have dete­ri­o­rated more than paint­ings from the 15^th cen­tury). Sec­ond, the paint­ings glow with a sense of vital­ity that is sel­dom seen in more recent paint­ings. They have a qual­ity that is often described as “jewel-like.” This is espe­cially evi­dent if you see them in per­son; it’s easy to pick out the Flem­ish paint­ings from those done in other peri­ods, or those from the same period done in other places. The pre­cise detail and gor­geous col­ors are mar­velous to look at.

The thing is, we now know a lot more about early Flem­ish paint­ing meth­ods than we used to, because mod­ern tech­ni­cal analy­sis pro­vides a lot more infor­ma­tion. So I can, with rea­son­able author­ity, describe actual “Flem­ish” paint­ing meth­ods, which were gen­er­ally much sim­pler than those taught in spe­cial classes where the “Secrets of the Old Mas­ters” are revealed.

The North­ern Euro­pean paint­ings we have are almost entirely done on panel, not because can­vas wasn’t used, but because panel paint­ings are the ones that have lasted. The pan­els were made of local hard­woods such as oak. They are often quite small; the large ones were made with sev­eral planks fas­tened together. The pan­els were planed to a smooth fin­ish and then sea­soned (usu­ally for sev­eral years). They were then coated in hide glue, which is a gelatin that becomes liq­uid when heated. Then an ini­tial prim­ing was applied that con­sisted of warm hide glue mixed with chalk (cal­cium car­bon­ate). This prim­ing was applied in sev­eral lay­ers, allowed to dry, then sanded or scraped smooth. The mod­ern word for a prim­ing layer like this is “gesso,” although tech­ni­cally gesso was the Ital­ian ver­sion, made from hide glue mixed with gyp­sum (cal­cium sul­fate). Mod­ern acrylic primer is often labelled “gesso,” but that’s totally incor­rect. Any­one caught refer­ring to acrylic primer as gesso will be required to stay after school and write “gesso is not made with plas­tic” 1000 times on the chalkboard.

There were very few pig­ments avail­able at the time to make paint with, although that lim­i­ta­tion is not obvi­ous from look­ing at old mas­ter paint­ings. The avail­able col­ors included ultra­ma­rine blue (very expen­sive as it had to be imported from Afghanistan and then labo­ri­ously refined), azu­rite blue (sort of like a cobalt blue), red lake (sim­i­lar to alizarin crim­son), lead tin yel­low (sim­i­lar to Naples yel­low), ver­mil­lion (sim­i­lar to cad­mium red), bone black (sim­i­lar to what is now, incor­rectly, called “ivory” black), flake white, cop­per green (sim­i­lar to virid­ian), and var­i­ous earth col­ors (sim­i­lar to mod­ern ochres, sien­nas, and green earths). Paint was made by hand, usu­ally that morn­ing or the day before, by appren­tices and stu­dio assis­tants. If you haven’t tried oil paint made fresh by hand, it is more fluid than the stuff you get today in tubes.

In the early 15^th cen­tury, oil painters prob­a­bly didn’t use sol­vents such as spir­its of tur­pen­tine or oil of spike. This demostrates that it is quite pos­si­ble to apply oil paint with very fine pre­ci­sion with­out hav­ing to thin it down. It’s eas­ier to do this kind of work with hand­made paint than with tube oil colors.

This method involves mul­ti­ple lay­ers that are allowed to dry in between appli­ca­tions. In some cases, lower lay­ers were done in egg tem­pera, switch­ing to oil later on in the sequence. Flesh tones were painted very thinly, in one or two lay­ers. The mod­ern oil paint­ing approach (mostly devel­oped in Flo­rence in the early 16^th cen­tury) empha­sizes thin, trans­par­ent darks and thick, opaque lights. By com­par­i­son, early North­ern Euro­pean paint­ing was pri­mar­ily a glaz­ing method in which darks were estab­lished with thick lay­ers of trans­par­ent paint. This allows the darks to have a sense of depth and color that is not pos­si­ble in direct (sin­gle layer) paint­ing. Glaz­ing is typ­i­cally done over a layer of opaque paint of sim­i­lar color; red lake over ver­mil­lion, for exam­ple. Black, since it tends to pro­duce dull mix­tures, is not used except to darken earth col­ors (most artists think that the idea of avoid­ing black was invented by the impres­sion­ists, but no). Instead, darks are cre­ated by thick glazes and by what we would today rec­og­nize as com­ple­men­tary color mix­tures (red lake could be dark­ened with ultra­ma­rine, for example).

Here’s one pos­si­ble recon­struc­tion of the paint­ing sequence:

1. Make a detailed draw­ing on paper and trans­fer it to a ges­soed panel. Rein­force and elab­o­rate the draw­ing with ink or dark paint. North­ern Euro­pean artists usu­ally made very detailed underdrawings.
2. The ini­tial layer of paint, called the primuersel, is used to define the dark areas of the paint­ing. The primuersel color is made by mix­ing black with earth tones such as red or yel­low ochre; it is there­fore sim­i­lar to the ver­dac­cio used for flesh tones in the tra­di­tional Ital­ian egg tem­pera method (but with­out a green earth under­paint­ing and not just in flesh tones). This layer was prob­a­bly often done in egg tem­pera or tem­pera grassa. Either way, this layer should be used to define form, edges, shad­ows, and other darks through­out the painting.
3. Now apply the basic col­ors to each area of the paint­ing, start­ing to work up mod­el­ing of forms with opaque col­ors but avoid­ing fine detail. This stage is called “dead col­or­ing.” As with primuersel, some artists used egg tem­pera or tem­pera grassa for this layer. Flesh tones can be begun with mixed tones using appro­pri­ate brown or pink mix­tures of white, ver­mil­lion, and earth col­ors. In light areas, keep the paint as thin as you can; you want the white of the gesso to show through. X-ray scans show that lead white was often used only to empha­size the bright­est high­lights of flesh tones, with a very thin ton­ing of the gesso used for most light areas of flesh. This approach keeps light areas bright and avoids later yel­low­ing by min­i­miz­ing the amount of oil. In shadow areas, don’t worry so much about paint thick­ness, but keep the sur­face of the paint smooth. In areas that will later be glazed, keep light areas lighter than the intended final effect, since glazes will darken what they cover. When you have taken this stage as far as you can, let the paint dry once again.
4. If you began the paint­ing in egg tem­pera or tem­pera grassa, you will switch to pure oil paint no later than when dead col­or­ing is com­pleted. Use paints ground in lin­seed oil. When switch­ing from tem­pera to oil paint, you may choose to apply a very thin layer of oil to pre­vent exces­sive absorp­tion by the tem­pera under­lay­ers. From now on, you will let each layer dry thor­oughly before fur­ther paint­ing. If the lay­ers are thin, this will take up to sev­eral days each time, depend­ing on the pig­ments you use and whether the paint con­tains sicca­tives. It may be help­ful to wet sand in between lay­ers as needed to main­tain a sur­face that is thin and smooth.
5. You will now work each area of the paint­ing toward the intended final fin­ish. Where desired, you can either thin the paint slightly with medium (oil mixed with a var­nish or bal­sam) or put a very thin layer of medium onto the sur­face and paint onto that. Apply fine detail to light areas. Areas of dark or bright col­ors, espe­cially those around the main areas of inter­est, can be glazed. So, for exam­ple, a red robe, after a primuersel of black mixed with red ochre and then ini­tial opaque mod­el­ing with ver­mil­lion and white, could then be glazed with a trans­par­ent red lake, using fin­gers, a rag, or a soft brush to make the glaze very thin over the lights and thicker over the darks. A lit­tle ultra­ma­rine or indigo could be glazed in to neu­tral­ize and rein­force the darker shad­ows. Mul­ti­ple glazes can be applied (allow the paint to dry and wet sand in between lay­ers) until a clear sense of three-dimensional depth has been achieved, gen­er­ally with inky darks, intense mid­tones, and bright lights. This process can be very time con­sum­ing, espe­cially if you are not using sicca­tives, but it pro­duces a strik­ing effect that is imme­di­ately notice­able when com­par­ing Flem­ish oil paint­ings to other work of the period.
6. The final stages would be used pri­mar­ily for detail work and to apply thin scum­bles of opaque color mixed with white where needed over lighter areas of glazed color. Again, sand between coats. It is pos­si­ble that some fine details were applied with egg tem­pera, worked into wet oil paint. This devel­op­ment of detail would con­tinue until a very high degree of fin­ish was obtained.