Varnish is a type of coating commonly seen in daily life, and it may be that shiny protective layer we see on wood or artwork. The reason why I say “maybe” is that some paints have a very similar appearance to varnish. When we analyze the internal composition and working principle, you can be sure whether it is varnish or not.
What is Varnish Paint?
Varnish is a clear, hard and durable coating. It is an organic coating formed by a combination of natural or synthetic resins, oils and solvents. It is applied thinly to the surface and dries to form a tough, transparent film. It is usually used to protect the surface and enhance its appearance. Unlike paint, varnish does not contain pigments or colors. Its function is to protect the surface and give it a beautiful high gloss or satin effect.
What is Varnish Paint
The history of varnish paint dates back centuries and is one of the oldest in the coatings category. It is believed that the ancient Egyptians and ancient Chinese (Tang Dynasty) civilizations used egg whites, natural resins and oils to make varnish to protect paintings. With the advancement of human civilization, varnishes have continued to develop, and many synthetic Varnish Paints have been developed by adding various chemical ingredients to improve durability and ease of use. By the 17th century, varnish had become an important assistant in the woodworking and painting art industries, and artists and craftsmen used it to protect and enhance their works. Today, varnish is still widely used for furniture finishing, art protection and various industrial applications.
To really understand what varnish is, it is important to know what varnish is made of. The composition of varnish is usually composed of 4 main components: resin, oil, solvent and additives.
Resin is the main component of varnish. Early varnishes were natural resin solutions extracted from plant secretions, including dammar, copal and rosin. It is made by heating the resin, adding natural oils such as linseed oil, cooking the mixture to the desired viscosity, and then diluting it with turpentine.
Today, natural varnishes have been largely replaced by varnishes made from synthetic resins. Most modern varnishes are a blend of resin, drying oil, drier, and volatile solvent. Among them, there are mainly alkyd resin, polyurethane resin, phenolic resin, vinyl resin and epoxy resin. The choice of resin affects the durability, finish, and drying time of the varnish.
Oil (usually linseed oil or tung oil) helps to enhance the flexibility of varnish paint, making it less likely to crack over time. The addition of oil also helps to apply the varnish smoothly and evenly.
Solvents are used to dilute varnishes, making them easier to apply and drying faster. As the varnish dries, its solvent portion evaporates and the remaining components oxidize or polymerize to form a durable, clear film. Common solvents include turpentine, mineral spirits, and even water (water-based varnish paint).
Additives are optional ingredients. The varnish can be formulated according to its specific properties, such as UV resistance, resistance to yellowing or faster drying times.
The differences and proportions of the ingredients in varnish paint directly determine the gloss, protection, flexibility, and durability of the coating.
Varnish has been able to develop to this day in the long river of history, and it must have irreplaceable advantages. From a modern and objective point of view, the correct use of varnish can indeed gain many advantages. For example:
- Waterproof: It can protect the surface from rain in the daily life environment.
- Protect: Varnish can prevent scratches and abrasions on the tabletop (any wood). Also protects artwork from dust, dirt.
- Enhance beauty: Enhance the natural grain and texture of the material, providing a consistent gloss, satin or matte effect.
- Environmental protection: Low VOC water-based varnish and natural varnish are conducive to the development of green ecology.
How Does Varnish Work?
The function of varnish is to coat and cure the surface of the material into a hard, transparent layer. When we paint, spray or roll varnish onto a surface, the resin in the varnish sticks to the surface of the substrate. The resin component acts like glue and forms a strong bond between the substrate surface and the varnish.
The role of varnish
During the application of varnish and after painting is complete, solvents begin to evaporate. During the evaporation process, the remaining resin and oil begin to harden, and the varnish solidifies from a viscous liquid into a solid coating. Over time, the resin in the varnish hardens to form a tough, transparent film. This film provides the above-mentioned protection against moisture, dirt and scratches.
When applying varnish over primer or undercoats, the varnish is combined with the primer. The primer or undercoat provides a smooth, stable surface for the varnish, so the entire protective coating can last longer. Without a primer, the varnish is more likely to peel or chip over time.
In either case, maintaining a clean, smooth substrate surface is always an important prerequisite for determining the effectiveness of varnish curing. The specific varnish coating steps can be read in detail in our corresponding blog.
FAQs
Is varnish the same as Polyurethane?
Varnishes and polyurethanes are different. Polyurethanes are a synthetic resin of water-based or oil-based plastic resins that offer greater durability and abrasion resistance. Varnishes are older in development and are made from a mixture of resins, oils, and solvents.
