I’ve just read a claim that Phthalocyanine migrates through dried oil paint. (Virgil Elliot’s facebook group.)
Is there any credibility to this claim?
I have not heard of this before, nor experienced it in over 40 years of working with it, but as an admin of the group, I would like to respond to the comment with more than my personal experience.
Also, is Phthalo classified as a dye?
Thanks in advance
Ron Francis.
Correction, it was George O’Hanlon’s facebook group, not Virgil’s.
Thanks Brian,
The Gottsegen reference surprised me.
Phthalo green and blue are all I use between ultramarine and cadmium yellow light, so I would have thought I would have noticed bleeding, although most of the time it’s usually a fairly small portion of a mix.
Ron Francis
Since the phthalo blue and green pigments are insoluble in water and most organic solvents they are, by definition, not dyes. They are prepared from phthalo dyes but are coordinated on copper (and with chlorine in the green variant). The phthalos are very high in tinting strength and quickly overpower other colors. They are also composed of very fine particles. Both of which can lend the appearance of bleeding, especially if the lower phthalo containing paint layer is not completely dry.
Having written the above, the late painting materials expert Mark Gottsegen wrote in his seminal treatise that phthalo blue was only fair-good in terms not bleeding through dried paint layers. It may be that this issue is perhaps a bit true on both sides. However, while I do not care for the overpowering nature of the phthalos, I have never experienced this myself either.
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