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Purpose of this Blog is to become a tool and a place where artist that collect and paint flat figures can find interesting links and news about flats, painting techniques, history and various related articles.English speaking related sites are very few but hopefully this blog will provide the collector and the painter with interesting and valuable information about the Art of the Flat Figure and everything related to it.
During the next days I will post any related info I have collected for a long time about various aspects of Flats. Techniques, photos, links, historic articles, anything that is related. Wherever possible I will including the author of the original article. I apologise if sometimes the author's name is not included. It's not intentional but it is lost through time.

Wednesday, 27 June 2007

Introduction to Shading with Complementary Colors

Introduction to Shading with Complementary Colors
by Einion Rees
Figure modellers generally use one of two schools of shading: complement shading and what I term hue shading, when you use a violet to shade crimson or brown to shade orange for example. The later is quite easy to use and can give acceptable results but the former is regarded as providing a closer approximation to what is observed in the real world - shadows are not only darker, they typically also show a loss in chroma, which hue shading does not accurately replicate but complement shading does. These two methods do not have to be mutually exclusive however - since one provides subdued, more realistic shadows and the other provides brighter, more intense shadows you can pick and choose between them depending on personal preference and circumstances and even use both principles together. The underlying principle of complement shading is very simple but there can be little doubt that it is tricky to implement for most people; the basic rules take only a few minutes to learn but a more complete appreciation can take quite a while longer. I hope this will help speed up this process, with a fairly comprehensive explanation of the rules and a large number of specific examples. If you approach this methodically and above all practice there is no reason why the hobbyist cannot soon match or exceed the mixing abilities of professional artists.

In addition to their use in shading, complements used sparingly are the best way to slightly dull a colour, for example if you want a brick-red for a Colonial-era British coatee Cadmium Red Medium is a good start but is far too intense straight from the tube; if you mix in a little green however it will be a much more acceptable match. This guide is aimed primarily at oil painters who on the whole have bright, intense colours in their palettes that really need to be subdued for modelling purposes; any discussion of complements I feel should additionally include recommendations on colour for the palette and these will all be artists' colours. Those using hobby colours can apply the underlying principles set out here to their chosen range with a little study and experimentation.
Before going any further it would be best to define some common terms for anyone unfamiliar with them.

Hue The specific character of a colour, e.g. an orange-red or a green-blue, its position on the colour wheel.
Value How dark or light a colour is, from 0 to 10, black to white. Cadmium Red Medium is typically about value 5.
Chroma How intense (bright or dull) a colour is, for example Cobalt Blue is high in chroma, Chromium Oxide Green is low in chroma.
Primary A colour that cannot be mixed from other colours, e.g. red, yellow and blue.
Secondary A colour mixed from two primaries, e.g. orange, green and violet.
Complement The colour opposite to another on the colour wheel, e.g. red and green, yellow and violet, blue and orange.
Subdue To dull down, to lower the chroma of a colour, usually by adding its complement.
Bias The leaning of a colour towards another, e.g. a green-yellow or an orange-yellow.

Theory & Practice
Please forgive the boring theory but as you will see a good understanding of the nature of a given colour and how it relates to others will allow you to foresee the inter-reaction between them with a fair degree of accuracy which will save you a great deal of time and, ultimately, paint. The colour wheel is a good theoretical model for colour mixing but has a basic flaw: true primaries don't really exist and by extension, neither do their complements. For example, if you could find a true red and a true yellow with no bias, as a typical colour wheel implies, when you mixed them together you would not get orange as you would expect, instead it would yield a dark grey, nearly black - a pure red and yellow would only reflect red and yellow light respectively and when mixed would cancel each other out. Now we all know you do in fact get an orange if you mix red and yellow. This is because in the real world colours only fall roughly into hue positions because all pigments also reflect other colours. If we take 'red' for example, invariably some orange and violet light; in the case of yellow, some orange and green light. The other colour they reflect the most of will be its bias, a leaning towards that colour, hence an orange-red or a green-yellow. So if we want to mix a bright, high chroma, orange we know we need a red and a yellow both with an orange bias and Cadmium Red Light and Cadmium Yellow Medium fit the bill. Conversely, and more useful for our purposes, if you want to mix a duller orange you might pick a red with a violet bias which with the same yellow will give a lower-chroma result. If you take this further by choosing a red and a yellow that both lean away from orange, a violet-red and a green-yellow, you will get a very subdued result which is what happens when you mix a crimson with a lemon yellow.
Illustrated on the right is a colour wheel similar to those you will have seen before, the difference being I have removed the 'primaries' and the 'secondaries' to more clearly show the hue positions you will actually encounter. Notice for example on either side of the position for yellow there is one that leans towards orange, the other towards green; similarly if you look at the red position you will see two types, one leaning towards orange the other violet. All colours exhibit some bias of this type, however faint, and the ability to see this is the first step in accurate colour mixing.

The Palette & Complements
More or less colours?
If we extend the underlying principle from the example of a mixed orange above, a workable palette would have to include at least two of each 'primary', one leaning in each direction: an orange-yellow and a green-yellow, an orange-red and a violet-red, a green-blue and a violet-blue. My personal preference is for a fairly small palette with the six hues above forming the basis. The advantages of a limited palette have been mentioned by myself and others many times before but are worth repeating here. Even if you consider the most basic two-primary palette as mentioned above (8 colours) the number of colours you can achieve by mixing is surprisingly large. If you imagine three steps from one colour to the next, for two-colour mixes there are 84 possible colours; if you expand to include white and black the number rises to 135. With a palette of 40 colours, certainly within the levels some have, the possible combinations are staggering: for two colours alone it comes to over 2,000! To put this into perspective, if you wanted to document the two-colour combinations with 8 colours, taking say five minutes for each mix it would take you 7 hours; for a palette of 40 colours, assuming you worked 8 hours per day, this process would take almost five weeks!! Work out for yourself how long the two-colour mixes would take with your own palette and you will see the benefit of being able to predict with a reasonable degree of accuracy the outcome of a given mix. In addition to the minimum requirement listed above, the earth colours are very useful time-savers when it comes to representing a host of natural materials from hair to groundwork. The ones I use and consider most useful are Yellow Ochre, Raw Sienna, Burnt Sienna, Red Oxide, Burnt Umber and Raw Umber. These and their equivalents will be discussed more fully below.

To find the correct complement, we need to know its hue so that we can find the opposite position on the wheel; in addition, for a complement to work well, it should have approximately the same value. If you look at the colour wheel above and compare it to your palette you will notice how the lighter and darker values are not represented. Since visually determining the appropriate complement is much easier than trying to work it out in your head (something I still have trouble doing) I have expanded the colour wheel to give an indication of value in addition to hue.

It should be possible to find a reasonable approximation to most palette colours and the colour directly opposite and in the same ring will be the correct complement as in the two examples. It's important to remember this is the ideal situation, if you are seeking a complement and you don't have a colour of the correct hue or value as long as it is close it will still work reasonably well - this is why Cobalt Blue works so well as a complement for many oranges and earth colours as you will see below. Also remember you can mix a secondary colour of any hue you want if you have a good selection of primaries, keeping the number of colours in your palette down and money in your pocket.

Hues and pigment recommendations
My palette includes no commercial mixes and only one secondary colour but I have included in the list secondaries that others might like that I feel are of some benefit. You will notice there are no colours like Naples Yellow, Payne's Grey or Sepia, all of which are simple mixes that can be replicated with a few moments' work, often to a better result (for instance choosing between Titanium White and Zinc White to mix Naples Yellow so that it is opaque or transparent as you prefer). All colours are given with their Colour Index Number to enable you to look for and identify the pigments recommended below, very important considering the plethora of commercial and proprietary names for paints. I would look upon any artists' range that does not provide these numbers with extreme suspicion in this day and age.

Green-Yellow - complement Red-Violet
Azo Yellow Light (PY3)
Also called Arylide Yellow Light and Hansa Yellow Light. Be sure to look out for the number PY3, as a similar colour PY1 is not as lightfast.
A bright, light yellow with a slight green bias. It is fairly transparent so makes a good glazing colour.
Complement: try Quinacridone Violet with some white.

Cadmium Lemon (PY35 or PY37)
If you would like a more opaque example of a green-yellow this is the colour to look out for, however its covering power will still not be very good.
Complement: as above.

Orange-Yellow - complement Blue-Violet
Cadmium Yellow Light (PY35)
The cadmium yellows are totally lightfast, fairly opaque and regrettably expensive.
Cadmium Yellow Light should be slightly biased to orange but check before you buy, it may be the green-yellow variety mentioned above.
Complement: Dioxazine Purple plus white should work well.

Cadmium Yellow Medium or Deep (PY37)
Different manufacturers formulate slightly different versions of this family varying from a fairly light orange-yellow to a near-orange. I prefer the medium shade, as it is the most versatile.
Complement: as above but with less white.

Yellow-Orange - complement Violet-Blue
Cadmium Orange (PO20)
A bright, opaque yellow-orange. An almost indistinguishable hue can be mixed from Cadmium Yellow Medium and Cadmium Red Light if you want to save the hefty pricetag.
Complement: Ultramarine with a touch of white should work well or you could try Cobalt Blue.

Benzimidazolone Orange H5G (PO62)
Similar to Cadmium Orange, it is slightly more transparent. Again, a very similar colour can be achieved by mixing.
Complement: as for Cadmium Orange.

Red-Orange - complement Green-Blue
Perinone Orange (PO43)
Also called Indo Orange Red.
Can vary slightly from an almost true orange to red-orange.
Complement: try Phthalo Blue with a little white added.

Benzimidazolone Orange HL (PO36)
A good example of why you need to know and check Colour Index Numbers, the name could represent two quite different oranges.
Apparently a very close match for true Vermillion.
Complement: as for Perinone Orange.

Orange-Red - complement Blue-Green
Cadmium Red Light (PR108)
The cadmium reds are very lightfast and similarly expensive to the cadmium yellows with good covering power.
Cadmium Red Light is an intense, fiery orange-red.
Complement: Viridian or Phthalocyanine Green BS with white added should be close.

Cadmium Red Medium (PR108)
Also an orange-red, but slightly less bright and intense than Cadmium Red Light. I would choose either one, not both.
Complement: similar to Cadmium Red Light's but slightly darker.

Quinacridone Red Y (PR209)
A useful transparent medium-valued orange-red, much less expensive than the cadmium colours and better for glazing. Complement: see above.

Violet-Red - complement Yellow-Green
Pyrrole Red (PR254)
Varies from fairly unbiased to having a minimal violet leaning. Very reliable pigment.
Complement: as for Naphthol Carbamide.

Naphthol Carbamide (PR170)
Sometimes called Naphthol Crimson.
A fairly bright red with a slight violet bias. A useful colour similar to Pyrrole Red.
Complement: try a mix of Azo Yellow Light and Phthalo Blue.

Anthraquinoid Red (PR177)
This colour would make an excellent replacement for Alizarin Crimson with better lightfastness.
Complement: Phthalocyanine Green YS should work okay or you could mix a green as above.

Quinacridone Carmine (PR N/A)
A deep violet-red, this is also a very good replacement for Alizarin Crimson if you can find it.
Complement: Phthalocyanine Green BS should be a nearly perfect complement for this, mixing almost to black.

Red-Violet - complement Green-Yellow
Quinacridone Red and Violet (PV19)
This same number is used to define a small family of pigments, with a host of additional names like Quinacridone Rose, Permanent Rose etc. They are all equally lightfast.
Varies from a fairly bright violet-red to a saturated red-violet.
Complement: because of its value, an exact complement needs to be mixed, try Azo Yellow Light and Phthalo Blue.

Quinacridone Magenta (PR122) Although defined as a red this is usually closer to a red-violet as the name would suggest. Complement: similar to above but lighter in value.

Blue-Violet - complement Orange-Yellow
Ultramarine Violet (PV15)
This is probably the best of the blue-violet pigments available today and Winsor & Newton's may be the most useful as it is lighter in value and very saturated.
Complement: although not dark enough Cadmium Yellow Deep is closest to the ideal complement. You could also try Yellow Ochre or Mars Yellow.

Dioxazine Purple (PV23RS)
Also known as Carbazole Violet, look for the RS (red shade) which is slightly more permanent.
A deep, slightly unsaturated blue-violet. A nearly identical colour can be mixed from Ultramarine and Quinacridone Violet.
Complement: see above.

Violet-Blue - complement Yellow-Orange
Ultramarine (PB29)
Occasionally still called French Ultramarine after its origin. The classic violet-blue pigment, dark valued and intense.
Complement: Cadmium Orange should work well or you can mix an orange of the right type.

Cobalt Blue Deep (PB73)
Probably the best of the other violet-blues available, this is slightly lighter valued. A rich, dark blue with a hint of violet. Unfortunately this and its sister pigment below are extremely expensive.
Complement: as above.

Cobalt Blue (PB28)
To the naked eye this is very close to a true blue but it usually has a slight leaning towards violet. Not essential on the palette but a useful mid-blue starting point.
Complement: Cadmium Orange or Raw Sienna should both work almost perfectly.

Green-Blue - complement Red-Orange
Phthalocyanine Blue GS (PB15:3)
Also called Phthalo Blue, Monestial Blue and Winsor Blue. There is a red shade, PB15:1, also available. If you only see PB15 you need to check it to see which type you have.
An intense, dark-valued blue similar to Prussian Blue, it is slightly more reliable but more importantly is slightly 'cleaner', resulting in brighter greens when required.
Complement: Perinone Orange is probably your best bet or again, a mixed orange of the same hue.

Cerulean Blue (PB35)
This is a very different blue to Phthalocyanine Blue GS being much lighter valued. Very useful for light mixed greens, replicating lighter blues and as a neutraliser for fleshtones.
Complement: Perinone Orange with the addition of white or a light-valued mixed red-orange plus white.

Blue-Green - complement Orange-Red
Phthalocyanine Green BS (PB7)
A beautiful intense example of this hue, Phthalocyanine Green BS also mixes the cleanest tints.
Complement: Cadmium Red Deep is not quite dark enough but close enough to work well. Any darker red will work fine even if the hue is not quite right.

Viridian (PG18) Can vary slightly but almost always a clean, saturated blue-green. The only green I have on my palette.
Complement: same as above.

Yellow-Green - complement Violet-Red
Green Gold (PG10)
One of the only true yellow-green pigments, this is unfortunately no longer manufactured.
Complement: If you already own this colour or can locate a tube, Naphthol Carbamide or Pyrrole Red should work as complements.

Chromium Oxide Green (PG17)
A useful medium-valued yellow-green noted for its opacity and muted character.
Complement: any of the violet-reds recommended above should work okay but also works with Cadmium Red Medium as their values are nearly identical.

That covers the twin-primary hue positions and their matching secondaries. With the addition of white and black, a selection of the above colours would make a fine palette: totally reliable, very lightfast and with a useful variation in opacity.

Earth colours
The natural pigments these colours are based on are getting rarer and more expensive and will slowly be replaced with synthetic replacements. These should be as lightfast but they may not be able to match the exact character of each colour so it might be worth locating and purchasing stocks of any colour you are very fond of for the future, if you are not already too late.

Yellow Ochre (PY43)
A slightly neutralised medium yellow probably with an orange bias.
Mars Yellow (PY42) is very similar but usually more opaque and a touch darker.
Complement: would be a dull blue-violet, Ultramarine Violet and white will work fine or you could mix a closer match from Phthalo Blue and Cadmium Red Medium plus white.

Raw Sienna (PBr7)
This pigment has sadly almost completely vanished already, replaced with a mix of Mars Yellow (PY42) and Mars Red (PR101) typically. The good news is that Winsor & Newton's Quinacridone Gold (PO49) is a nearly perfect match in hue and transparency. Other manufacturers offer this pigment as well but you might want to check its character before you buy.
Complement: Cobalt Blue should be nearly perfect.

Burnt Sienna (PBr7)
A fairly dark, slightly neutralised red-orange noted for its transparency. As with Raw Sienna this is almost unavailable today. By reputation the replacements, usually PR101 or a mix of this with a yellow, can be very similar but I would check if possible before you buy.
Complement: Cobalt Blue also works quite well here, illustrating the point that you don't need an exact complement.

Red Oxide (PR101)
Light Red, English Red, English Red Oxide, Venetian Red and Indian Red are all quite similar.
An opaque, slightly neutralised, medium valued, red-orange. Mars Red has the same number and can be almost identical in hue and many Red Oxides are now made from this synthetic pigment.
Complement: Cobalt Blue works for this too, but Phthalo Blue works okay, giving a less neutral, cooler result.

Raw Umber (PBr7)
Apparently this can vary quite a bit from a dark yellowish olive-green to the more typical green-brown shade I prefer. I like it for warming up whites and as the basis of a good earth colour.
Complement: Quinacridone Violet should work well to neutralise this colour but you would need to add a touch of white to see the result.

Burnt Umber (PBr7)
This is usually the darkest of the earth colours, a deep chocolate brown sometimes with a slight violet look. Noted for producing 'chalky' mixtures with white, this can vary with the manufacturer.
Complement: because of the variety available an exact complement is impossible to advise, but Ultramarine usually works very well and you could try Viridian as well.

This final diagram shows examples of the hue positions listed above with representations of their direct complement. I have concentrated on the twin-primaries with a selected secondary in each case.

For anyone interested in knowing more, I highly recommend Blue And Yellow Don't Make Green by Michael Wilcox, ISBN 0891346228. This book presents the first fundamental analysis of practical colour mixing that experiment will bear out, with clear explanations of the technical issues, many colour mixing examples and recommendations for the palette.

If you can locate a copy, I have also found Liquitex's small booklet How To Mix & Use Colour useful, primarily for its colour table at the back (although it uses the Munsell hue positions which don't quite gel with Wilcox's theory) with a unique and very useful guide to colour relationships and matching. It also lists the pigments used in all the Liquitex colours, including their mixes, allowing you to easily make your own Sap Green, Parchment, Payne's Grey etc.

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