The watercolors of Nila Colori are prepared by means of trituration of the natural pigment already finely powdered together with a mixture of gums: the main one is gum arabic of Kordofan quality, already purified and food-grade. This is the most transparent and colourless gum arabic, therefore it doesn’t produce any change to the original color of the pigment. Other gums are added to give the right texture to the watercolor and the right behaviour during the painting. We chose to use vegetable glycerin as a wetting agent, to guarantee the right amount of moisture and so that the color can easily be dissolved with a wet paint brush.
- Lightfastness. Mineral pigments are the most stable to light within the ones available in the world: light radiation has no effect on them. The materials we use to prepare vegetable and animal pigments were on the other side chosen within the ones which could guarantee an high fastness. To scientifically guarantee it, we commissioned a test according to the ISO 105-B2 regulation: the results were beyond expectation and they are reported in each color sheet.
- Transparency. Used pigments have different degree of transparency, starting from an high grade owned by vegetable lakes, till high opacity of genuine indigo for example.
- Effects of granulation. Natural pigments have the property to show very interesting effects of granulation, because of the dimension of particles above 20 microns: they’re not distinguishable to the naked eye, but their behaviour isn’t like the one of colors in solution typical of inks yet.
- Non-staining. The size of particles above 20 micron doesn’t allow the pigment to penetrate into the paper sheet: it’s just stuck to it thanks to the binder. It allows the artist to almost completely delete the color by means of water to obtain peculiar effects, otherwise hardly acheivable. Thanks to the right binders, glazing works can anyway be obtained over already painted color.
Carlo Ferrara, MSc. ChemEng
