A look at the properties that define watercolours as a modern fine-art medium and how to assess them
In my first ARTicle “
Watercolour”, I looked at the historical development of watercolour as a modern fine-art medium and put forward my thoughts concerning the reasons why it had become so popular. There is no doubt that it is seen as a traditional art medium and any technological advances in its manufacturing or materials used in its formulation, have been kept low key, so that it retains its old-style charm. But it was because of the chemical advances in the latter half of the 19th century that the techniques that we now recognise as being of the essence of modern watercolour, began to be used; the overlay of transparent washes, using the white of the paper for highlights, painting onto wet paper in order to allow the colours to mingle and blur, the techniques that are unique to this fine-art medium.
In this respect, the artists who experimented with watercolour and developed these unique techniques and the colourmen that formulated with the new raw materials, defined modern watercolour and the properties that are seen as unique to this art medium. But what exactly are the properties that are so prized by today’s watercolourists, who are following on from these 19th century pioneers?
The Properties of Professional Watercolour
There is a lot of information out there, in magazines and on the internet that describe the properties of watercolours that are highly prized by watercolourists.
1. Transparency and Opacity;
2. Permanence or light fastness;
3. Granulation;
4. Staining and non-staining;
I am intrigued that this list of properties follows the information that is generally found on each watercolours label, or in the manufacturers’ marketing information and doesn’t include what I would consider the most important properties a watercolour must have, purity of colour and its intensity (or brightness)!
My own list extends the list further to 10 properties:
5. Purity of colour;
6. Colour intensity or brightness;
7. Tinctorial strength;
8. Wet to dry colour shift;
9. Re-solubility;
10. Wet-in-wet flow.
Now we have our list of properties to assess, how do we prepare our test piece, which should not vary in film thickness, but be the same every time?
In general, it is difficult to reproduce the exact film weight when painting or brushing out watercolour. Dilution may also be difficult to control, as the brush will almost certainly contain additional water after it has been cleaned between painting out the watercolours on test. Therefore, it is normal to prepare test pieces by painting each watercolour out using a graduated wash, (preparing a graduated wash is covered in part 1 of “Tips for Practicing Traditional Techniques”). In so doing, it makes it easier to compare samples at similar film weights by moving the wash of the test sample up and down the one its being compared too, until the equivalent film weight can be seen.
Test 1: Transparency and Opacity
Painting a watercolour over a dark background will determine if a watercolour is transparent, semi-transparent or opaque. Assessment should only be made after the colour has dried.
A word of warning, painting over a pencil or ink line may interfere with the lay of the colour over the line (as can be seen in figure 2a), so I use black card in order to avoid a false result (see figure 2b).
Test 2: Permanence or light fastness
Watercolours should be labelled with the pigment number to show which pigment they are made with. If there is just one pigment number, they are a single pigment colour. If there are two or more, they are made from mixed pigments. The pigment numbers are a form of classification of the chemistry, by the Society of Dyers and Colourists.
These pigment numbers form the Colour Index, which not only gives the chemical composition, but also commercial names and manufacturers. In terms of the Colour Index pigment numbers, light fastness test data and permanence can be simply obtained from a quick internet search.
A simple to do light fastness test can be done by taking a graded wash of the colour to be tested, cover one half and then place it in a position inside a window where it will receive the most direct sunlight. Leave it for several months, checking it every week by examining the uncovered part against the one that is covered (figure 2). Note any difference.
Figure 2: Checking watercolour wash for any colour changes during a test for light fastness.
The light fast watercolour will show no change, either by darkening or lightening.
Test 3: Granulation
On painting out, there are 2 ways a pigment granulates to give a mottled appearance, it either flocculates as the water evaporates or if the pigment is heavy, it settles out in the dimples of the watercolour paper. By painting the watercolour out on smooth and rough paper will determine if it flocculates and by which mechanism.
If you use only one type of paper, you will most likely only be concerned how the watercolours behaves on your paper, so just paint out a graduated wash and inspect at the different graduations.
Figure 3: Granulation of A J Ludlow’s Titanium Orange on Cold Pressed (NOT) watercolour paper.
Test 4: Staining and non-staining
To check if a watercolour is staining or non-staining, the test is fairly simple. Paint out the colour and then when it is dry, use a wet brush or cloth/tissue to lift out a portion of the painted colour.
It the watercolour lifts out cleanly with no staining, then it is a non-staining colour.
Again, if you use only one type of paper, you will most likely only be concerned how the watercolours behaves on your paper, so just paint out a graduated wash and inspect how the colour lifts out at the different graduations.
Test 5: Purity of colour
The test piece is prepared by painting each watercolour out using a graduated wash. In so doing, it makes it easier to compare samples at similar film weights by moving the wash of the test sample up and down the one its being compared too, until the equivalent film weight can be seen. Purity of colour can be checked by eye.
Figure 5: By cutting the side off one of the test sample washes, the watercolours can be compared
can be compared directly by placing them against each other.
I hope this ARTicle has been of interest to you. Its content is presented as a video, “Assessing Watercolour Properties” and can be found on our YouTube channel, “Ludlow Colours” along with our other videos.
In next month’s ARTicle, I will continue looking at how to test for the other five properties listed above.
