What Is Paint and How Is It Made?
The first use of paint can be traced back to the French and Spanish people. More than 20,000 and 25,000 years ago, artists used natural substances to make paint. Things like earth pigments, charcoal, juice from berries, lard, blood, and milkweed sap, were often utilized. The Egyptians and Hebrews used it as a protective coating for the wood on their ships. In the 1700’s, Thomas Child built the first American paint mill. It was located in Boston, Massachusetts. The first patent for paint was purchased in 1865 by D. P. Flinn. However, it wasn’t until 1867 that this company began mixing paints for consumers. Before 1930, stone mills were used to grind the pigments. Later, these were later replaced by steel balls. These days, sand mills and high-speed dispersion mixers grind the dispersible pigments.
The Complex Process of Making Paint
Most people don’t give paint much thought. They see it as nothing more than a colorful tint that is applied to their walls. However, paint is more than just a color, it is a liquid material that dries to a beautiful finish. It takes a complex chemical process to turn this liquid into a solid. Paint is used for beautification, protection, sanitation, and even identification. Consequently, many have no clue what paint is made of and the process that is used to generate it.
The Ingredients in Paint
There are four main components in paint, they are resin, additives, solvent, and pigment. The resin is the binder that holds all the pigments together. It allows the product to adhere to the surface is it painted too. A water based paint uses acrylic emulsion polymers to bind. Common acrylic polymers come in a wide variety of types and combinations, such as methyl and butyl methacrylate. Inexpensive paints use polyvinyl acetate to bind.
Additives are used to enhance the properties of the substance. It makes it glide on the wall with a brush. It also makes it mold and scuff resistant. Without additives, the drying time would not be as fast as it is and there would be sag resistance. Solvents act as a carrier that helps bind the pigments and resin together. These agents can be organic, like mineral turps, or the manufacturer can use plain water.
Lastly, pigments are used to give paint its color and sheen. They are placed into two groups, prime and extender. The prime pigments will include colors like white, green oxide, yellow and red. In the other group of extenders, it includes calcium carbonate, talc, mica, and barytes to name a few.
The Manufacturing process
There are five critical parts in the manufacturing process of paint, they are a measurement of ingredients, preparation and pigment dispersion, Let-down, laboratory testing, and canning. Paint is manufactured in large lots. Using calibrated vats, the ingredients are measured and weighed on scales. Pigments are added next. These powders are small and stick together forming clumps. They are broken down by the resin and additives that keep them from sticking together, which is called dispersion. Mixers are used to combine and disperse the pigments.
In the let-down stage, the resin, solvent, and additives are combined in a large vat. The mill-base is stirred in during this phase. Any final additions are added during this stage, if necessary. The finished product is tested in a laboratory. Before manufacturing is approved, critical ingredients are tested. They will ensure it is sufficiently mixed and no further processing is needed. They check the viscosity, tint strength, color, gloss, dry time, and overall appearance.
When the batch is complete, it can be canned. Two samples are taken during this phase. A retained sample is kept and stored for future references, and then there is the final inspection sample. The final sample is inspected to guarantee conformance to standards. Once the final sample has been completed, it can be dispatched.
Understanding Lacquer and Enamel
The humblest types of paint are lacquers that generate a film by evaporation of the solvent. A water based paint has trillions of tiny resin particles. The water in these paints slowly evaporates and the resin and particles become closer until they are touching. The resin and pigments fuse, forming a tough, solid that is known as paint film.
Enamel paint is made from an alkyd resin that is dissolved in a solvent. As the solvent evaporates in the first stage, it forms a tacky lacquer. The resin reacts with the oxygen in the air and forms a hard coating. Coating paints have two components that are unreactive alone. However, when they are placed together, they undergo a chemical reaction. The reaction may take some time, depending on the room's temperature. The final result is a hard, tough coating that has great adhesion.
As new technologies continue to develop, the boundaries between water based, solvent based, and reactive coatings are becoming blurry. For instance, some enamels have water based emulsion resins that produce polymerization of the dried film. This is similar to what is seen in solvent based enamels.
Byproducts and Waste
The process of making paint creates a lot of byproducts and waste. Any manufacturing plant must have an in-house wastewater treatment facility. This facility will treat all the liquids that are generated on-site. It will also handle, store water run-off. These facilities must utilize the Environmental Protection Agency, or EPA, regulations. They must be monitored 24 hours a day as well as conduct periodic record checks. Any liquid waste can be treated on-site by the standards of the facility. The sludge formed from latex can be recycled and used as fillers for other products. Water-based solvents can also be recovered and used as fuels for other industries. A paint container that has been cleaned can be reused or sent to a local dumping facility.
The Color Pallet of Life
Very few people truly know how paint is made. It is one of those things that is used every day with little background information. Paint is used everywhere. From the home to the office and even the car. Without color, the world would be very bland.