Have you ever wondered what is in your paint? We’ve been using the stuff for thousands of years. Do we still follow the same recipe used by the ancients? What makes paint stick to the wall or keep its vibrant color? If you’ve had any of these questions, come with us as we take a dive into the composition of paint.
A Brief History of Paint
Since the dawn of civilization, people have been decorating surfaces with pigment. Perhaps the earliest iteration of paint can be traced back between 20,000 and 25,000 years ago, to caves in France and Spain. These ancient Raphaels created their “paint” with the substances they had available to them, natural pigments from the earth, minerals, rocks, charcoal, lard, blood, sap, milkweed, and berry juice.
Those days are long since past. Nowadays, instead of scouring our own charcoal and lard, we have ready-mixed paints available on the shelf of any hardware store. This style of paint was patented in 1867 in the United States, leading to an explosion of paint factories springing up across the country.
In our modern age, people have access to paint in every color of the rainbow and beyond. Despite this variety, the composition of paint remains relatively uniform.
The Composition of Paint
The bottom line is this: paint is pigment suspended in a liquid or even paste vehicle. Such vehicles often include media such as water and oil. The basic composition of paint includes four ingredients: pigments, solvents, resins, and additives. All manufacturers follow this formula, opting for their own concentrations of each.
Pigment
Pigment gives paint its characteristic color. It is generally the first thing people think of when they consider the composition of paint. In fact, pigment is the ancestor to paint as we understand it now. Societies of the past—the Greeks, Romans, Egyptians, Chinese, and Hebrews—all experimented with pigments to create a sort of proto-paint. These were used to decorate walls and crockery. They used things like oils to add varnish and utilized pigments like chalk, red and yellow ochres, arsenic sulfide yellow, and malachite green.
In the manufacture of paint today, most pigments are synthetic because they actually help to stabilize the paint mixture. However, we still have a wide variety of natural pigments in circulation, hundreds of colors and sources. For example, black pigment is commonly made from carbon black. Carbon is added to the other components of paint to give a vivid color.
Solvent
The solvent is the soup in which all the other ingredients of paint can come together. Its liquid nature allows for easy mixing, and once the paint is placed the solvent evaporates to allow it to dry. Fifteenth century painters began using drying oils as their solvents to hasten the drying times of their masterpieces.
They also introduced linseed oil as a new solvent which was the staple until synthetic solvents put it out of work. The most common synthetic solvents are volatile with low viscosity, making the aromatics (alcohols, esters, ketones, acetone and benzol) the perfect fit.
Resin
When it comes to the composition of paint, resin acts as a binder, the glue which holds everything together. The ancient Greeks and Egyptians used substances like beeswax, lime, gum arabic, and egg albumen for resin in their paints, and by the time the Middle Ages rolled around, artists would boil their resin with oil to make paint easier to mix.
In modern paint, we still use many natural resins like soybean, coconut, and linseed oils. Synthetic resins are also common and include compounds like epoxies, acrylics, polyurethanes, and alkyds. In addition to holding the paint mixture together, resin allows paint to adhere to the surface being painted.
Additives
Additives are the most diverse component found in the composition of paint. They are completely dependent on what the manufacturer wants to accomplish with the paint. Each additive introduces specific performance characteristics to the batch of paint to improve it in some way. These may include stain resistance, scuff protection, sag prevention, rapid drying, or fungicidal properties.
Some additives are designed to make the painting process more streamlined. These can be referred to as thixotropic agents and can smooth out paint, minimize skinning, minimize settling, or minimize foaming. All these help paint to last and to cover well. In some cases, such as the addition of aluminum silicate or calcium carbonate, additives merely give paint more substance and body. They do not change any of the other properties of the paint.
