How Paint is Made & The History
How Paint is Made, Developed, & Manufactured
Some spend time searching for the best exterior paint, but have you ever wondered how paint is made? Here we are going to help you understand this fascinating material’s origins and properties. It will help make sure your house painting project turns out just the way you want.
In this article, we will explore the origins of paint before explaining exactly how it is made so that you can have a better idea of the material you’re using for your project.
The Origin of Paint
Surprisingly enough, paint is one of humankind’s oldest inventions, dating back nearly 100,000 years ago. For example, in Blombos Cave in South Africa, a stone toolkit used to grind ochre into ancient paint was dated 70,000 years old! In those times, paint was typically composed of natural earth pigments, charcoal, lard, blood, and berries. Early paints were not solely used for art and decoration. The ancient Egyptians and Hebrews utilized paint as a protective wood coating for ships.
Throughout the centuries, there were several materials used to make paint. Lead white paint, the most popular white paint in use for generations (until titanium dioxide replaced it in the 1800s due to lead’s health hazards), was developed by the Greeks in the early times.
In the early 1700s – the very first American paint mill was built in Boston by Thomas Child. Meanwhile, the very first patent for paint was given to D. P. Flinn in 1865, and a few years later, Sherwin-Williams began selling mixed paint for consumers (in 1867).
Paint Raw Materials & Compositions
Today, there are four main parts to any paint mixture. These are the resin, solvent, additives, and of course, the pigment (which gives the paint its color).
The resin acts as a binding agent, holding all the paint’s pigments together and allowing it to dry and stick to the applied surface. Typically, water-based paints will use acrylic emulsion polymers (such as methyl and butyl methacrylate) to bind together, while more inexpensive paints will use a form of polyvinyl acetate. White alkyds and epoxies are also commonly used as resins. In addition to these synthetics, there are various natural resins in use, most widely substances like lin-seed, soybean oil, and coconut.
Paint solvents are used to combine the paint’s resin and pigments to form a single compound. Commonly, water is used as a solvent, in addition to organic materials like mineral turps. Generally, solvents are volatile liquids with low viscosity. Benzol, alcohols, esters, ketones, and acetone are all in use as solvents today.
Meanwhile, the additives (as the name suggests) serve to “add to” or enhance the paint’s properties. Some additives are simply fillers that provide more substance for the paint material without modifying its characteristics in any way, while other additives can produce desired characteristics. The latter type of additives would include thixotropic agents that provide a smooth texture and driers, defoamers, anti-skinning, anti-settling agents, and others. Additives can make the paint application easier, provide mold and scuff resistance, and more.
Finally comes the most critical ingredient: pigments. Without pigments, the paint wouldn’t have its color. Hundreds upon hundreds of pigments exist, both synthetic and natural, but all are divided into prime and extender groups.
Prime pigments include standard colors like white, yellow, and red. The primary white pigment is titanium dioxide, while black pigments are better made from carbon black. Extender pigments derive from materials such as talc, mica, and calcium carbonate. A variety of pigments are used to achieve the colors we know and love. Iron oxide and cadmium sulfide, for example, are used to create red hues. Meanwhile, iron blue and chrome yellows are used to make blues and greens, and metallic salts to create yellows and oranges.
How Paint Is Made
There are five main steps in paint manufacturing. The manufacturing process involves measuring the ingredients, preparation, pigment dispersion, let-down, lab testing, and canning.
All paint ingredients are measured using large, calibrated vats, then weighed on scales. Once each component is carefully measured and quantified, the pigments are added to the paint mixer. Typically, the pigment powders are quite small and stick together into clumps. The resin, additives, and solvents later serve to break down these clumps further.
Today’s machines used to combine and disperse these pigments throughout the mixture are typically large-scale, high-speed industrial sand mills, in a process known as “dispersion.” Sand mills are used to disperse almost all industrial paints. These mills are large cylinders that agitate tiny particles of sand or silica to grind the pigment particles, dispersing them throughout the mixture. This sand is later filtered out, leaving only the cleanly dispersed pigment.
However, nearly 90% of the water-based latex paints created for use by individual consumers today are processed not in a sand mill but in what is called a “dispersion tank.” Here, the premixed paste is put through high-speed agitation via a circular, toothed blade that is attached to a rotating shaft. This process serves to blend all the pigments properly, just like the sand mill does.
Following the dispersion process comes the let-down stage, where the resin, solvent, and additives are all combined in a large vat. The mill base is also stirred into the mixture during the let-down process, along with any final additions. The finished product is then put through extensive lab testing. The laboratory will test all critical ingredients, ensuring they are well-mixed, and carefully analyze all the key factors, such as the paint’s viscosity, tint, color, dry time, and gloss.
Finally, the paint is canned. Typically, twin samples are taken from each batch during this phase, with one sample kept for reference purposes and the second for one final inspection. Quality control methods vary, of course, but if at any point a sample does not pass inspection, the entire batch is generally cast out. However, if the final sample passes inspection, the canned paint is then dispatched to the retailer or consumer.
Paint is one of humankind’s earliest inventions, and it’s a substance that we as humans are continuing to innovate and improve. Just like the paint of yesterday was made with crushed berries and charcoal compared to the synthetic pigments and high-speed sand mills we use in modern times; the paint of tomorrow may be very different from the paint of today.
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