History of Paint Making
For thousands of years people have been adding colour to their surroundings in the form of paint. People from ancient times made paint in more or less the same way that we make acrylic paint in our workshop today. Until about one hundred years ago artists usually made their own paint, or had an assistant or colourman make it for them. The pigments were ground by hand on a flat piece of marble or glass using a glass muller. The finished paint was used right away or stored for a short time in animal bladders.
Today machinery helps the paint maker make bigger batches of paint that will keep well when stored in jars or tubes. But the principles of paint making haven’t really changed over thousands of years.
There are three main ingredients in paint:
Pigment to give the paint colour
Water to make the right thickness
Binder to hold the paint together and make it stick
The colour in paint comes from pigments. Pigments are coloured powders that come from all over the world. Each pigment particle is like a tiny piece of crushed rock. Some pigments come from the ground. These are called mineral pigments and are mainly earthy colours. Sometimes the name of a colour gives us a clue to how or where the pigment was made. Raw Sienna, a rich reddish brown, was originally mined from the hills near the city of Sienna in Italy. Bone black is made from burned animal bones. Other pigments are made in factories by combining different minerals, metals and chemicals and heating them up – so hot that they change colour. Some hi-tech pigments are created by scientists making chemicals react together to form new colours. These brightly coloured modern pigments often have long scientific sounding names like Quinacridone Red and Dioxazine Violet.
The Paint Making Process:
Heavy sacks of pigments arrive at the workshop in trucks. First, each ingredient must be carefully measured and weighed. Each colour has its own recipe that has been developed using many test batches to create the exact balance of ingredients to bring out the best in every pigment. The pigment and the water are mixed together with a small mixing blade. This stage is called wetting out the pigment.
This mixture is poured slowly into the mill so that the pigment can be ground. Inside the mill, small, hard, stone-like balls, each one the size of a large grain of sand, smash against the pigment particles, crushing and polishing them and breaking them up even smaller so that as much of the colour as possible can be seen. Some pigments must be run through the mill several times. The ground mixture becomes a fine, smooth paste that is passed through a sieve so that the grinding balls are left behind.
Now something sticky needs to be added to hold – or bind – the pigment together and to allow it to stick to surfaces. All paints are made from pigments, but there are many different binders. Ancient people used animal fat as a binder. Ancient Egyptians used melted beeswax when they made elaborate portraits to decorate coffins. Many famous Italian Master painters used paint made from egg yolks. Native people here in the West Coast of Canada used crushed salmon eggs to make paint for their wooden masks and totem poles. Many great painters have worked with oil paint made from linseed or poppy-seed oil.
The binder in acrylic paint is acrylic resin – a liquid plastic. When it arrives at the workshop in big barrels it is a slightly white-ish liquid but when it dries it will become a completely clear and shiny film. A strong, pulsing pump sucks the resin through a hose and into the big mixing tank where it is added to the pigment paste. Lines are marked on the inside of the tank to measure how much resin needs to be pumped in. Small amounts of different chemicals are added to help the paint to stay smooth, thick and fresh.
A large circular blade with notches and turned up edges is lowered down into the tank. The blade is hooked up to a powerful motor that makes it spin very fast. The speed of the blade brings out the colour in the pigment even more and makes sure all the ingredients are completely mixed together. Once it has been mixed for exactly the right amount of time at exactly the right speed, the blade is raised up out of the paint and the paint is ready for packaging. The paint is emptied through a valve like a tap at the bottom of the tank. It is transferred into a hopper with a funnel that feeds into a portioning machine.
An air powered piston filler squirts measured amounts of paint into tubes and jars. The open ends of the tubes are then melted shut by pressing them between the heated jaws of a sealing machine. Jar lines have to be screwed on tight so that no air can get in and the paint stays fresh.
Each jar and tube must be correctly labeled. A stroke of the paint is brushed onto the label so that you can see exactly what colour is in the tube. Now the paint is ready to be sold.
Paint for artists are usually made with just one pigment. It is the artist’s job to mix them together to make even more colours. Some artists like to start with just three primary colours; red, yellow and blue, and do a lot of their own mixing. But most artists like to start with a larger range of colours including green, violet, brown, black and white. There are thousands of different pigments in the world and each one makes a different coloured paint.
The Paint Making Process In-Depth
Acrylic colours begin with pigments. Pigment 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:
-transparency or opacity
-light to dark value
-ability to withstand heat
All of these qualities influence the properties of the finished paint.
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, where 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 tent 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 then has ever been possible before, reaching areas of the gamut that were previously inaccessible to painters. They are ideal for use in glazing techniques. Quinacridones, Phthalacyanines, 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 labeling 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 artists colours just as linseed oil is in artist’s oil paints and as gum-arabic is in watercolours.
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 pigment 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 pigment 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.
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 pigment to determine the gloss levels. One reason for doing this is that this will produce the more 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.