The Quinacridone Pigments

Posted by Marc Jackman on

First appearing in 1958 as automobile colorants and artists' paints, Quinacridone solutions are yellow to orange in colour but depending how they are processed the final colour can differ, the available hues range from; golden yellow (PO49), through reddish orange (PO48), middle red (PR209), coral (PR207), red/rose (PV19), rose (PV42), magenta (PR122, PR202), maroon (PR206), and a deep reddish violet (PV19).

This is why not all Quinacridone Rose Watercolours are the same, they all depend on how the pigment was processed by the manufacturer and then the different processes and binders used by the watercolour manufacturer

One thing they do all have in common is that although these beautiful pigments all share the same transparency, vibrancy,  permanence and replaced the fugitive natural organic pigments such as Rose Madder making them excellent choices for any artists’ palette

Quinacridone Rose on our triple roll mill

 Quinacridone Rose on our triple roll mill

Our current range as of (30/09/2020) at Jackman’s is: Quinacridone Rose (PV19) (Available 31/10/20) , Quinacridone Magenta (PR122) & Red Violet (PV19)

 

The Science

Bruce from Handprint puts this the best:

The structure of beta quinacridone PV19 is characteristic: two pairs of oxygen and nitrogen atoms set in five (hence the "quin," for five) interlinked rings of carbon. Chemical variations arise from groups of atoms hung symmetrically from both sides of the molecule, which act both as auxochromes to modify the color and as complementary chemical bonds that link the quinacridone molecules into chemically more stable crystal chains. (The diagram shows the nitrogen/hydrogen and oxygen components of PV19 in these auxochrome locations.) For example, substitution of these auxochromes by methyl (CH3) gives PR122 and by chlorine (Cl) gives PR202. Interestingly, a solution of quinacridone molecules typically is a pale yellow to orange color: the pigment color is actually determined by the particle size, the crystal modification, variations in the auxochromes, or by crystallizing together different quinicridone molecules, including quinacridone quinone or even other pigments (a proprietary pigment by Ciba-Geigy, PR N/A, is a mixed crystallized form of beta quinacridone with a diketo-pyrrolo pyrrole). Much of the color variation arises from differences in the way the quinacridone molecules combine into crystals, which can be altered through grinding with salts or heating in solvents.

 


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