about KROMA

the paint making process

Acrylic colours begin with pigments. Pigments are very small insoluble coloured particles – often smaller than a micron - ranging in many different shapes and sizes.
Each pigment has a unique character made up of many factors:

• particle size
• tint strength
• flow properties
• transparency or opacity
• sheen
• light to dark value
• lightfastness
• weatherfastness
• ability to withstand heat
• cost
• toxicity
• rarity
• vehicle compatibility
• chemical resistance
• colour
• colour saturation

All of these qualities influence the properties of the finished paint.

Cadmium yellow pigment

KROMA makes acrylic colours from pigments created in three eras of pigment history. The oldest colours in the palette come from the earth; compounds of iron oxides yield muted hues of red, yellow and brown. Carbon and Bone black are natural materials. Some of these pigments have been known since prehistoric times. These less expensive pigments are usually opaque and tend to have a matte sheen.

Processes for altering mineral and metal compounds, often including intensive heating, were developed during the industrial revolution creating brighter colours such as ultramarines, cadmiums, and chromium oxide greens.

Modern organic pigments are made from molecular materials that have central atoms of carbon. Because of their small particle sizes modern pigments tend to make colours of very high tinting strength; bright hues that are naturally glossy and transparent. These new pigments produced colours that were cleaner and more saturated than had ever been possible before, reaching areas of the gamut that were previously inaccessible to painters. They are ideal for use in glazing techniques. Quinacridones, Phthalocyanines, Hansas, Benzimidazolones - These modern pigments have gradually replaced some of the traditional pigments, outperforming them in lightfastness ratings, in cost and in health risks. For example, Alizarin Crimson has a poor lightfastness rating, and has largely been replaced with pigments from the quinacridone group. Paint manufacturers, when replicating the colour and characteristics of a traditional pigment by using blends of modern pigments, sometimes use the term hue with the name of the traditional colour. Cadmium Red Hue for example, is usually made of naphthol red blended with various other pigments. This can lead to some confusion about which pigments really are in which paint. We have chosen not to make "hues", but to use the actual pigment names of each colour. Sometimes we have chosen to shorten the full chemical name for the sake of simplicity. Benzimidazolone we have shortened to Benzi; Phthalocyanine we have shortened to Phthalo. When we have blended more than one pigment to create a paint, we have noted the pigments used on the labelling and on the pricing list.

The first stage in paint production is the sourcing of high quality pigments and resin. KROMA colours are made from pigments that come from as far afield as Spain, Italy, Germany, England, U.S.A., and Mexico. All the pigments that we use have very good or excellent lightfastness ratings.

The pigments arrive at our workshop as sacks of coloured powder. To transform the pigments into paint, the particles have to be separated from one another in a grinding process, then evenly dispersed in liquid, and suspended in a binder. Acrylic emulsion resin is the binder in acrylic artist colours just as linseed oil is in artist’s oil paints and as gum-arabic is in watercolours.

mixing paint	rotor used for mixing paint

Unlike oil colours, acrylics are fast drying and dilutable with water. Once dry, the acrylic forms an incredibly flexible film, which is resistant to water and chemicals. Because the acrylic resin dries perfectly clear, the full intensity of the pigment’s colour can be seen.
KROMA paints are formulated for medium viscosity, making them suitable for the widest range of applications. The thickness of the paint does not correlate to the amount of pigment that they contain. Among other differences, student grade paints contain fillers and extenders that may create a full-bodied paint, but which has weak tinting strength and less intense colours.

All KROMA colours are fully loaded with pigment. Each colour is formulated individually to ensure the optimal amount of pigment for each recipe. For example, because Quinacridone pigments have a very small particle size, a high proportion of resin is needed to encapsulate each particle in order to create a good film. Cadmiums, on the other hand, which have a larger particle size, require less resin. In all cases the pigment to resin ratio has to be carefully determined. In general, pigments with larger particle sizes yield opaque colours, while pigments with smaller particle sizes yield transparent colours.

filling	finished product

The viscosity of the paint can be altered by the use of clear acrylic mediums, either to make it more fluid, or make it fuller bodied, or as a way to extend the paint to make the colour ‘go further’. The unique characteristics of each pigment will affect the sheen of individual colours. Some manufacturers choose to add matting agents to their paint to create a range of paint with a uniform sheen. We have chosen to allow the nature of the individual pigments to determine the gloss levels. One reason for doing this is that this will produce the most saturation of colour and the highest loading of pigment possible, since the particles of the matting agents dull the colour and take up space. The sheen of the paint can then be altered by the individual artist as required, by adding clear mediums to the paint, or by adding a coat of clear medium to the finished work or by adding matting particles such as diatomaceous earth.

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