First watch this ring. Which name would you give to the colours A, B, C and D? We would chose to A: warm green or ochre green, B dark gold ochre or light brown, C red brown and for D bluegreen, also called turquoise.
Physically this colours are however dark yellow (A), dark orange (B) and dark red (C). D is indeed bluegreen but that same on our version of the colour circle below seems rather a light blue!11 is in fact light blue, but looks more purple to us.
Primary colours are 1, 3 en 5. We did prefer the version with the yellow on top because it shows the evolution from cold colours on the left to warm on the right. Of course all colours should be gradient, nevertheless we choose frames to give us a better insight in the colour spectrum. For a complete correct presentation a sphere should be used, the colours 1, 2 and 3 as well as everything in between could be a horizontal circle, with white and black as the Nord and South pole of the sphere, the exact middle being neutral grey. For practical reasons we did prefer to put everything on one surface, because a computer screen is still 2D. The outer ring shows the colours of the main ring mixed with grey.
Our brain does not experiences colours objectively. The tones of the primary colours in our circle are the most intense on the computer screen, called the RGB colours (also the green and the violet are called RGB colours). However the blue (5) looks rather dark to us. In paints it is named middle blue. Although the colour on the left between the middle blue (5) and vived green (6) is bluegreen, it resembles more light blue. The three basic colours construct all other colours and tones, include black and white. In light white is the sum of the the three primary colours, black the lacking of any light or colour. The three primary colours to light however are green, red and blue (with yellow being the mix of green and red. The printing of our colour circle is made with three basic colour pigments: yellow (1), violet (4) and blue (5). The pigment for the violet is called magenta, the printer creates vivid red with mixing magenta with yellow. Good printers have a colour more, the complete black. If one changes the mode from RGB to CMYK, the printer will additionally use that black pigment, because the RGB black of a print is not that perfect. There is no white pigment in the printer, white will be limited to the colour of the used paper. Paints however have different pure whites, more intense then any colour of paper or gesso (primer on the canvas). Here on the screen there is no white in the center of our colour circle (25), it is in fact a light gray. If it would be really white, the light coming out of the screen would blind the eyes. Colour tones are somewhat different from one screen to another, it depends on the light source and the chosen clarity of the screen.
On our colour circle 13 looks what it is, dark yellow, thanks to the pure colours standing beside it. The A in the picture on top is however identical to the colour 13 on the second picture. On the first illustration is shown in B how we experience 14 as a brown, but it is identical to the dark orange on 14.
We do not have specific words in our vocabulary for the light tones of blue or green. On the contrary red with white we call pink, light violet is called lila. The name 'light red' however indicates a red closer to orange on the colour circle, not the pink. The name 'dark yellow' on paint tubes is the most yellow kind of orange, not the ochre green shown in A or 13. The light blue (11) on our circle is not our choise, it is the mathematic mixture of the computer's most vivid blue with white. It does look a bit purple to us. Bluegreen is more recognisable in the ring of dark colours (between 17 and 18) instead of the main ring.
Names as indigo, carmin, vermillion, purple and ultramarin are not colour names, but pigment names. Often used as if it where colour names nowedays, referring to an explicite tone. Indigo is a very dark tone of blue, vermillion is red going to orange, carmine to violet. Purple is the blue violet as produced by the purple snale and ultramarin is the blue of lapis lazuli, nowadays made synthetically.
For the construction of our colour circle we choose the tones as given by programs as Photoshop.
The indexed colour on the right top of the square is RGB yellow. The middle of the right side is the dark yellow colour 13 on our colour circle. The precise middle of the square is always the corresponding colour in the outer ring. The tone on the upper edge, one thirth length form the 'pure white', has made our inner circle.
A square is not the ideal represention (but very practical however) of colours, some pixels are repeated. The both corners on bottom for instance are the same 'total' black. The correct form of diagram would rather be a piece of pie, with the RGB yellow on top of the circle radius. The program Painter uses a triangle which is a more logic representation.
Chosing colour in the program Corel Painter
Each brand of artist's paint present their colour cart on the internet. But we cannot see those colours on our screen, because it is always transformed in the three basic colours. The printed colour carts are not very good too, although some brands use up to seven basic colours for their prints. If you want to see the real colour, you have to look at the colour cart in the shop where the real paint has been added on strips of canvas.
Artist's paint can have very intensive colours not to be seen on an electronic screen, although it doesn't seem that way. If you mix colours on the screen it will give an expected and logical result. Yellow and blue will give green, yellow and red will give orange... Mixing pigments however will not always give a predictable result. For example mixing a vivid blue with a vivid red does not end in a vivid violet. For that purpose one should take a vivid violet pigment.
All factories are free to chose the name for their colours, so you must realise that the used name of the colour can be misleading. An artist's paint which takes itself serious, as well as the artists using that paint, give the number of the used pigments. Some are pure and some are mixed. Those numbers can be checked on the site of pigment numbers, the colour index of artiscreation.com. You can click on any pigment to see it's composition or fabricage and ASTM lightfastness.
Which pigments are more reliable? Many years ago one could say the nonorganic pigments last for centuries to come, while the organical are more futile. So little organics where used by the best painters. Much saints on old fresco's now have olive green faces because the organic pink faded away while the underpaint of green clay did stay. However the Southamerican maya blue, made of indigo on palygorskite clay, remained as blue as 6000 years! And indigo was made of plants untill 1870. Carmine, coming from female insects called Coccus cacti, has also stayed quite good from gothic times until now, having become a bit brown. Alisarin crimson was a lake made from plants and did not maintain. Nowedays alisarin crimson is copied with a thirth branch of pigments, the petrochemical group. It is indicated as organic, but is in fact more 'organics made inorganic'. Their lightfastness is often I, the highest, but some of them are II or worse. Inorganics where originally digged pigments, later on augmented by chemically made colours, such as viridian, Prussian blue, later on cadmiums and cobalts. So it is not always an improvement when famous prigment factories have changed their cadmiums and cobalts into petrochemicals. They may still call it cadmium or cobalt, but if you check the pigment numbers it is revealed they are not.
Some examples. In Mussini oils cadmium yellow and red are still cadmium, the cobalt violets and blues are still cobalt. They stopped in selling cadmium green, which is a mixture of cadmium yellow with viridian (or phtalo green, the petrochemical). Their ceruleum blue or sky blue is still a cobalt-tin-oxide pigment, it was regarded as the most stable blue. Their Manga-Coelinblau, which was a cobalt too, is now a zinc oxide-phtalocyanin blue. Cobalt green is an irreplaceable pigment but not every brand still sell it.
Prussian blue is nowadays often a petrochemical replacement, as well als Naples yellow. Naples yellow was originally a lead pigment, lead antimonate yellow pyrochlore (PY41), a colour that cannot be replaced by a hue. It is a commonly known that lead, cadmiums and cobalts are toxic pigments, whicht means you cannot eat them. I recommend to carefully handle them, not painting with fingers, not eating or drinking during painting. But for artists cadmiums and cobalts should not be missed. Cobalts and cadmiums are always cat. I, very opaque and as basic layers they stand on the second place after digged minerals and leads. Petrochemicals can be cat. I, II or III, and are completely or partially transparant. Lead, cadmium and cobalt in small amount are natural while their petrochemical replacements are a pollution for the environnement.
Rublev produces a lot of oil paints with ancient pigments. However synthetic iron oxides have the same lightfastness as the digged pgments. Moreover petrochemical pigments not only replace but also create new brilliant colours such as phtalogreen and phtaloblue, irreplaceable and with a lightfastness cat. I. Cadmiumred is a perfect and very reliable red in different tones, opaque. Let's take a look at some petrochemical reds from Wiliamsburg, from half opaque to transparent. Pyrrole orange is cat. I, an excellent vermillion, it becames famous as colour of the Ferrari sportcars. Pyrrole red is cat. I in acrylic, not rated however in oil and WC. Their 'Permanent crimson' is an anthraquinone, cat I in oil but III in WC. Their quinacidrone red is cat I in oil for the best brands, cat. III in WC, brilliant red in a thin layer, becomes violet when thicker. Naphtol reds are never above cat II.
Titanium white and zinc white, two environnement polluters, are now quite common and of excellent lightfastness. Titanium white is quite durable, but has it's limits. For use of ground layers lead white is much better. For colour mixing lead white is also much better, because titanium white is so strong and opaque it is dominating in mixture. Brands as Rublev, Williamsburg and Oldholland still sell lead white, which is lead carbonate. Lead sulpate has been popular once, under the name 'non-toxic lead white', it could also be a mixture of lead sulphate and other whites. Rublev even offers different lead whites. Pure lead carbonate is opaque, but less dominating then titanium. The 'flemish white' is warmer and slightly less opaque. Rublev also offers four semi-opaque whites, venetian white, ceruse, crystal white and mica lead white. Venetian is half lead carbonate and half barium sulphate. While titanium white has limits, zinc white is a total disaster. Painted zinc white turns into a kind of glass during the years, jumping of the canvas in shatters. If oil is painted over acrylics or acrylic gesso, zinc white should even never be used as part of a mixture, nor any colour containing zinc oxide.
Small view of the colour cart of Winsor&Newton water soluble oils. The number of colours is limited, but this oils make it possible not to need terpentine. There are still cadmiums and cobalts present, but they are followed by a 'hue' colour, which simply means a petrochemical replacement. Cobalt green is missing. Their 'cadmium red hue' is a mixture of naphtol scarlet, cat I in oil en II in WC, and naphtol red, cat II in both. So that colour is cat II. Mixed white is as disastrous as pure zinc white.
Colour mixing with oils and acrylics
General principle four colour mixing in oils and acrylics. We can on ly show this colours here in approaching RGB colours.
With oils and acrylics colour mixing is not exactly according to the colour circle. Secundairy colours can be mixed with primary colours, but the result is not that pure. You can obtain a better result by placing two colours at the main poles in a bit different tinting. Yellow has become here a lemon yellow and a middle yellow. There is now a red with orange tint and one with purple tint. Also a blue that is a bit greenish beside a reddish blue. We show green as an exemple. Number one stand for the perfect brilliant green pigment. Number two is your mixture with poles standing closest. With number three the result is a more dirty, muddy green, greyish and brownish.
There re several ways of mixing. As working layer upon layer, the upper layer is a more transparant glacis of a colour wrubbed out with a harder brush. In pointillism colour dots where placed beside eachother. Severini painted colour lines. Well known is wet-in-wet, but here we regard the mixing before painting, creating a new colour.
In each brand e certain colour is nevertheless somewhat different. The mixtures are personal, and so are their names. So it is more wise to show general schemes for mixing trials.
Colour mixing, variants of red
The main part is the left side, the group with the red browns. Mixed with white they give different pinks. This pinks can be mixed with the other colours mensioned around, including black or even heavenly blue. Darker colours are made without white, such as a bronze red.
On the right four exemples of pure reds. Raises the question witch red to chose. Orange to deep red exist in cadmium colours, but the problem is that cadmiums lose their cat I lichtfastness in mixtures withlead, cupper, chrome, sulphur and arsenicum. Some sources even mention iron oxide to the list. Painting layer above layer is no problem to cadmiums. The petrochemical reds are more transparant, and cat II. Only quinacidrone red is cat I. A very intense red is obtained by painting quinacidrone red glacis on brown red.
Colour mixing, grey tints
Mixing black and white, adding a touch of colour is of course most easy, but the two frames show a better result. It's always about a blue and a brownred earth colour. Accourding to the proportions the result is a warmer grey (more brownish) or a cold grey (more blueish). Within a colum it's a matter of 'or'. Lamp black mixed with white it a bit brownish, bone black with white a bit blueish. Grey in clouds is often best with some lila tinting: Indian red with ultramarine, Prussian blue or indigo, and add yellow ochre.
Colour mixing, greens
Here also 'or' in each column. A yello green is made by black and yellow. Evolving the yellow to orange makes it more brown. A yellow green can of coarse also be made with green and yellow. Other tints of yellow result in olive greens or brown greens. More bluish green is mixed with green and blue. It is also possible to simply mix cobalt blue with yellow, but the combinations presented here make better results. The whole can be mixed with some white too.
The most brilliant greens are light and deep cadmium green, not easy to buy. It's a cadmium so it is better to use it pure and paint another colour on top. Cadmium green should not be mixed with phtalo greens, viridian, sap green or green gold because of the copper. Nor with cobalt green, it contains chriome. Cobalt green should not be mixed with organic colours, such as petrochemical colours (with hue's such as contemporary indigo) or bone black. Cadmium yellow and greens should not be mixed with iron oxides. Cadmium can be mixed with titanium white, cobalt blue, ceruleum blue, lamp black, and also with umbers, raw siennas and ultramarine because they do not react on any colour.
Bought browns are the umbers and sienna's, and the brown red iron oxides. Vandycke brown and sepia are never imitatied perfectly, but they are cat II lightfastness. Some mixture exemples:
amber brown = 6 burned umber x 4 chrome green x 3 burned sienna
cupper brown = white + black + ochre + sienna
wood brown = 3 Indian red
x 2 black x 1 yellow ochre (or more ochre and less black)
terracotta = Indian red x white x red
olive brown = burned umber x lemon yellow
purple brown = Indian red x ultramarine to purple x lamp black
Vandycke brown approach =
umber x touch of red
other brown = quinacidrone red x burned sienna x middle yellow
Witch yellow is most suited for this middle yellow? A middle cadmium yellow layer with the glacis of quinacidrone red and sienna on top. For real mixing there is only the most genuine Naples yellow of Rublev, containing lead. Chrome yellow as well as the petrochemical yellows (such as arylide) do not have the highest lightfastness. Vanadium yellow is a bit greenish and nickel titanium yellow is an excellent light yellow. Indian yellow does not exist anymore, the name is now used for replacements, often for petrochemical yellows, with Mussini it is a nickel dioxine complex, which is cat I in oils.
There exist also some browns even more suited for glacing, they are different to each branch. With Mussini Lasur-Orange it is Diketo-Pyrrolo-Pyrrol, so cat II in oils. Their Lasur-Oxide-Rot is cat I while an iron oxide, and their Lasur-Gelb is a nickel-azo complex, a cat I replacement for gamboge.
Johan Framhout, November 2018