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| Tints of Prussian Blue (Prussian Blue mixed with Winsor & Newton Titanium White) : Winsor & Newton, Rublev, Vasari, and Michael Harding (from l-r) |
In a recent post titled "Testing the Tinting Strength of Paint," I shared Frederic Taubes' method for evaluating the pigment concentration of artists' oil paint. For my example, I compared Prussian Blue from Winsor & Newton with Rublev Prussian Blue from Natural Pigments. Those results can be seen here.
One reader suggested in the comments section that I follow up his this examination with a lightfastness test of the two tints I mixed. I thought this was a great idea. I have since re-mixed the tints of Prussian Blue with Titanium White using the same proportions as in the earlier post, and have added two other brands to round out the test: Vasari, and Michael Harding. The four mixtures appear in the image above, and in the image below next to a Xrite ColorChecker. Additionally, since Prussian Blue is a transparent paint, I have made color swatches of the same four brands as glazes, which I will also test for lightfastness. Rather than adding a medium to these paints to precipitate flow, the paints were taken directly from the tubes and scumbled on the canvas ; this seemed to me to be the best way to represent the paints as they are manufactured, without the fear of any unequal adulteration by me.
The results of these tests will be posted sometime next year.
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| Scumbled glazes (l-r): Winsor & Newton, Rublev, Vasari, and Michael Harding |
This has been an interesting exercise for me, and I have enjoyed examining the differences between the paints. My initial observations are that Rublev Prussian Blue was the most pigment rich of the four. It was also the most red of the four blues, as both a tint and a glaze. Vasari Prussian Blue, when added to Titanium seems to have the least pigment, though not significantly less than Winsor & Newton or Michael Harding. As a tint, Vasari grayed the fastest, but as for glazing, it seemed to be the most chromatic (and most green). Winsor & Newton and Michael Harding Prussian Blues mixed to a similar value when added to Titanium White, though as a glaze Michael Harding's Prussian Blue was the more chromatic (and red) of those two. Winsor & Newton was least chromatic of the four as a glaze; when mixed with white, it remained the most green of the four tints.
Prussian Blue has been in use as a pigment since about 1724, and over the course of time, it has suffered a mixed reputation in terms of permanence. However, ASTM currently rates Prussian Blue as having excellent lightfastness, and I expect that any problems observed in the past were the results of using poor quality or counterfeit materials. I do not imagine that any of these four particular oil paints will fare badly in the lightfastness test.
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| Scumbled glazes from top to bottom: Michael Harding, Vasari, Natural Pigments, and Winsor & Newton |