23350 Indian yellow, imitated (nickel-azo complex)

The hue of the different types of Indian yellow can vary. However, it is in the dark yellow or golden yellow range. Some Indian yellow types are coloristically identical to the corresponding cadmium yellow types. Three fundamentally different types of Indian yellow are now known.

1. indian yellow genuine (purree) - not available.

Via Persia, the production of Indian yellow was introduced to India in the 15th century, where it was mainly used as a bright yellow color. In European painting, the natural dye became known only in the middle of the 18th century. Indian yellow was obtained from the urine of Indian cows that had previously been fed mango leaves and which were then left to thirst for a long time. The evaporation of the urine produced a yellowish-brown, insoluble residue. This was collected, washed and sold as a pressed spherical bale. For animal welfare reasons, the production of genuine Indian yellow was banned at the beginning of the 20th century. This pigment, which was said to have legendary durability properties and a color beauty that could not be imitated, has disappeared from the market since the beginning of this century. Chemically, this Indian yellow is a natural organic dye, being the magnesium salt of euxanthic acid (chemical composition: C19H16O11Mg-5H2O). To date, it has not been possible to produce this product in industrial quantities. The production is too expensive. Purrée or Piruri is the raw product obtained from urine. Indian yellow is quite lightfast, only slightly soluble in water and not at all soluble in alcohol. It dissolves well in acids and alkalis.

2. imitation Indian yellow.

With the development of dye chemistry, more and more lightfast pigments from the family of azo dyes (azo from French "azote" = nitrogen) with approximately or even comparable glaze and resistance properties came onto the market. Today, these pronounced glaze pigments are processed by the artists' color industry into Indian yellow substitutes. Pigments available under the name Indian Yellow also belong to the azo group. Unfortunately, however, the artists' color producers add extenders to these pigments, also for reasons of easier processing. The same applies to the technical processing guidelines for these Indian yellow substitute types as is listed under "Permanent yellow".

3. imitation indian yellow (nickel-azo complex), PG 150. our product no. 23350.

By incorporating a nickel atom into the azo dye, the industry has succeeded in producing an extremely lightfast complex dye. This Indian yellow has very high color intensity and excellent glazing properties. The pigment is extremely fine, thus requiring a very high binder and is not easy to rub on. When applied thickly, the shade appears dark golden yellow, almost brownish, the thinner the glaze, the more the shade tends towards light yellow. When mixed with white, shades more reminiscent of the various shades of Naples yellow are achieved. The pigment is suitable for all techniques, but is best used as a pure glaze. In very acidic or basic systems, the nickel atom can be dissolved out, which can lead to a color change and reduced light fastness. In aqueous media, it is somewhat easier to wet than other tar dyes due to its metal content and somewhat higher specific gravity. The large grain fineness, however, requires very thorough incorporation. After wetting with isopropyl alcohol, it must be worked through very carefully. Only when the pigment has "broken down" should binders be added. When working into emulsion paints (acrylic), it may happen that the dispersion already functions as a wetting agent.

Page 1 of 2

Kremer Pigmente GmbH & Co. KG · Hauptstr. 41-47 · DE-88317 Aichstetten ·Tel. 0049 7565 914480 · [email protected] · www.kremer-pigmente.com

We do not assume any warranty for the guidance shown above. In any case, we recommend production and evaluation of samples.

For small amounts, and they are usually sufficient because of the high intensity, a very thorough spackling with linseed or walnut oil is sufficient when making oil paint, and an addition of 1:2 dammar solution can further increase the brilliance. However, best results are obtained by first rubbing the pigment with isopropyl alcohol using the glass runner. After the alcohol has evaporated, take a spatula and scrape the pigment together. Only then do you add oil. It is amazing to observe how the color paste becomes more and more solid the longer you work oil into it. Oil should be added drop by drop until a normal, smooth tube consistency is achieved.

It is unclear how the correspondence of Indian yellow and Aureolin (cobalt yellow) mentioned by Kittel came about.

Page 2 of 2

Kremer Pigmente GmbH & Co. KG · Hauptstr. 41-47 · DE-88317 Aichstetten ·Tel. 0049 7565 914480 · [email protected] · www.kremer-pigmente.com

We do not assume any warranty for the guidance shown above. In any case, we recommend production and evaluation of samples.