Saturday, 6 February 2016

More on Pigments

My recent piece about the latest Winsor & Newton limited edition set raised a number of interesting questions. One of these was what was the point of buying them and wanting more, when you would be unable to buy replacements? Primarily due to the researches and knowledge of  a Facebook friend Zvonimir von Tosic we now possibly have some answers. I know that many artists are not that interested in pigments as such but it is a subject that fascinates me, even though I don't claim great technical expertise in either knowledge or approach. Without Zvonimirs input this piece would not have arisen so I am greatly indebted to him for discovering things are not as simple as they sometime appear.

Previously I have always consulted Handprint - and still do  - even though Bruce McEvoy ceased to update it several years ago.Much is still relevant but like all things nothing stands still. The pigment database- - is also a good source of information but quite technical.

Here is what Zvonimir has to say and I quote him in full:

"All right, I think I have an answer Peter. I have explored a little, so here is a brief summary. When producing certain types of pigment, say PV15 (this is one of the pigments used in a paint they call  `Smalt' in the latest W & N limited edition -PGW)., pigment manufacturers can obtain different `shades' of the colour, perhaps hundreds, depending on manufacturing process (errors, trials, beginning of run, end of run, stability of process etc).

However when analized spectographically, the wavelengths of all those batches are still within the acceptable range to be named PV15. But, our eyes being very sensitive to nuances, can tell the difference. In your tests of paints made `from seemingly same' pigments, but coming from different paint manufacturers like W & N, DS or Schminke, they may appear to differ. Therefore numbers`after' the number 15, and all manufacturers try to buy batches closer to their chosen shade.

What if all of them want to buy same, and at the same time, and there isn't enough ?

See chart (above). It shows variations on PV15 and PV14, which one pigment manufacturer is able to obtain( or has saved them in stock) in quantities ready to be utilised. They may keep batches piling up, or offer them to some paint manufacturers at a discount, who can make an interesting product out of them.

W & N reads industry newsletter, makes a phone call, takes a few tonnes of (PV)15583 for example, which looks bluer than what they used to buy for PV15, (in this case it may look like old Smalt). W & N purchases it, makes a limited run tube paint - perhaps because the manufacturer of that pigment does not or can not produce that specific variation in large quantities, and W & N knows what their users normally buy, with what types of colour shades users are happy with and can appreciate.

Colour recognition is a cultural phenomenon, and they play by the rules"

This has certainly widened my understanding of this subject. As said many may not be interested but to me it goes a long way to explaining why Permanent Rose from W & N (PV19) is such a favourite. And this applies to certain colours from other makers. I was aware that there are variations in pigments and have done posts where this has been highlighted,  for example PV19  where we have  red, rose and violet shades. 

One thing puzzles me slightly. Basically pigments are in two categories, natural and synthetic. With natural pigments like the earth colours there is considerable variation in shades, but I can understand this as they are mined and colours vary. Although it has been said these natural supplies are running out, and synthetics (PR101)  are replacing them,  there are still many available sources, perhaps not in such  large quantities. If you visit Provence you'll see this with shops selling nothing else and all sorts of colours visible in the rocks. In the Forest of Dean about thirty miles from where I live, between Bristol and Bath, are Clearwater Caves, a tourist attraction. Several earth colour shades are still mined there and sold in the shop, and on the internet I believe. 

With synthetics I would have thought they would be more consistent, being produced by a chemical process. I know the final result is determined to some extent by how the paint maker process the pigment and what additives they use. 

Here are five swatches, three of Ultramarine, two of PV14. The Graham Ultramarine Blue looks much darker than the other two but this may be my fault. Holbein and W & N look much closer. The above swatch is actually W & N French Ultramarine, and they also offer an Ultramarine `Green Shade'. With PV14 I've had problems with the Rowney version changing colour, a sludgy brown, and going hard in the tube. Another violet shade PV16, from Graham gave all sorts of problems and even the so-called final one - the third I received, using pigment from a different source according to Graham, has now also bitten the dust and has set like concrete!

As a final word Zvonimir has established from Graham that nowadays the same pigments are used in oils, acrylics and watercolours and the particle sizes are the same. This was apparently not so in the past. 


Zvonimir said...

Hi Peter,

Thank you for the article.

If I may add one more complication on top of that already explained in the article. It is following: each time pigment gets substituted with a new one, most certainly will affect something most dear to watercolour painters, and that is

(1) mixing properties of the pigment, and
(2) granulation.

In case of real Smalt paint, and this W&N Smalt hue, which is just a variation on PV15, two pigments are chemically DIFFERENT. Although on white paper, when applied alone, they may appear to be very similar, even identical, but chemically they are different and that will impact watercolour mixes and granulation.

Paint manufacturers behave like pigment substitutes are something of a virtue, a quest they are called upon all the time, not a problem of any sorts, and they approach to it as a feat that celebrates their ingenuity. Then they show how their new hues look on paper, and the story is then over, only very a loud applause is due.


In the matter of fact, no. An artist should really strive to understand their pigments better, because they could be alarmed for a reason. What manufacturers do not tell, is that colour mixes using pigment substitutes will most likely be different, because new chemicals will have different properties in interaction with other pigments, and because each new chemical has different gravity too, it will affect colour granulation, which is often employed to add charm to watercolours.

I always wondered why today's watercolours (when compared paintings of older masters, who lived just 70-100 years ago) tend to be very saturated even in light washes, pooling and patches regularly visible in work, washes often imperfect, mixes tend to be neutral or "muddy", with very little gradient (transition between hues) and poor transparency.

Now I think I know a little better.

If pigments are substituted on a regular basis, watercolour artists should at least DEMAND that pigment particle sizes used for watercolours are LARGER than those used for oils and acrylics, so that basic properties of the watercolour: 1. transparency, 2. negative painting, 3. granulation, 4. vibrant mixes, are all easier to obtain.

Zvonimir said...

I often see a marketing message that goes, "now we have updated and reformulated our watercolour range with XYZ number of colours, all lightfast, beautifully saturated, etc. ...". But what it means? It means following:

1. some totally new chemicals are introduced, that match in colour but God knows which ones and of which new mixing properties,
2. substitutes were not dictated by artist's real needs, but by the availability in the pigment markets, very much tied to automotive and chemical industries and their shifts.
3. because they come from those primary industries, pigments obtained are already ground superfine, that are unusable for watercolours because the brush load is too saturated, layering becomes difficult, although for oils they may work quite well, as traditionally, pigments were extra ground for oils to achieve greater covering power.

I see trouble. Unfortunately, watercolour world being traditionally connected with amateur artists mostly, they do not pursue matters as if their livelihood depended on it. What paint manufacturers do, they indeed care for needs of artists painting in oils first, of which many are professionals; use them for acrylics, perhaps most versatile and easiest medium which imitates oils; and only then use same batches of pigment to create crayons, watercolours, etc., almost as an afterthought, justifying abrupt shifts with marketing slogans.

We cheer because we get what we can get, although we pay twice as much for the same amount of pigment — and although we should be paying much more attention to pigment properties, and be more finicky. So yes, we miss Handprint indeed.