UV Coating, the Hard, Strong and Inexpensive Coating Finish

UV coating is a type of coating whose drying process occurs due to a chemical reaction (polymerization) that is triggered by energy from ultraviolet light. The coating is made from a mixture of resin with the addition of a material called a photo initiator. When the photo initiator is exposed to ultraviolet rays (with sufficient intensity), it will generate free radicals that will trigger a polymerization reaction in the resin, resulting in a dry and hard coating film layer. The drying process with this lamp energy gives many advantages in the finishing process. UV coating is a 1-component coating that does not require mixing with other materials, making it easy to store and handle. The coating will not dry as long as it is not exposed to UV light with sufficient intensity so that it can be stored for a long time without any issue about pot life as the 2 component material. 

The drying process of the UV coating is very quick; once the coating layer is exposed to UV light with sufficient intensity, the coating film will dry in a few minutes. The finishing process with UV coating can be very fast. With adequate equipment and facilities, the products that come out of the UV coating machine are fully dry. It can be immediately packed and sent to the user. The UV finishing room can be a small space; it doesn’t need a big drying room like other coatings.

UV coating was initially used to finish the wooden floors. The application of UV coating can be easily applied to the wooden floors because the floor is a flat board with small size and simple form. Moreover, the wood flooring finish is mostly simple in color and appearance, but more prioritizes strength and protection. The UV coating is lot of used to do the modern wooden floors, ranging from solid wood, laminated wood, veneered panels, and even synthetic wooden floors.

With the development of wood technology, the use of UV coating has also expanded to other wood products such as panels, walls, doors, and furniture. UV coating is one of the most popular coatings for modern finishing processes that require a fast, simple, and low-cost production process.

uv coating for flooring

Advantages of UV Coating

• Fast process

UV coating is the most appropriate finishing material to accommodate the modern finishing process that needs to be fast, easy, and cost-effective. The finishing process for UV coating is usually carried out with big equipment consisting of a series of rollers, ovens (UV lamps), and sanding machines that will work on the finishing stages sequentially. The product enters from one end and exits at the other end with a dry film coat with the desired color and appearance. The product that exits this machine is ready to be packed or assembled as a product that is ready to use.

• Very high transfer material efficiency

UV coating has very high efficiency of material transfer, meaning most of the finishing material that is applied on will stay to the surface with very little waste. UV coating can be made with 100% solid content without any thinner or solvent in the mixture. Thus, there is no cost-wasting for the thinner or solvent, which is the largest part of the conventional coating. Applying coating with a roller is also a process with very high efficiency because no material is wasted as dust spray as with spray applications. UV coating gives material transfer efficiency about 100%, much higher than other applications.

• High-built film

UV coating can produce a thick film layer quickly and cheaply. This coating can layer its underneath with high-solid material by adjusting its equipment. With the proper UV light, the thick film can be generated in a fast and cheap process. In the furniture coating, the UV coating can be used as a base coat to build the film layer before being followed by other coatings to make the high-built finish.

• Strong and hard film layer

UV coating can produce a strong and hard film layer. Once it is dry, the UV coating films are thermosetting, which are resistant to solvents, chemicals, and high heat. UV coating layers are also very hard and scratch-resistant; the hardness of the film layer can reach 8H pencil hardness, much higher than other coatings. That is why this coating is the most appropriate coating to coat wooden floors that require the maximum hardness and strength.

• Low end cost

In general, UV coating is marketed at a higher price compared to other coatings, but with its high level of efficiency, this coating will produce a cheaper end cost compared to other coatings. With the same film layer thickness, UV coating will require less than half in finishing cost than other conventional coatings.

Disadvantages of UV coating

Although it has many advantages, UV coating also has disadvantages that limit its use. Here are some disadvantages of UV coating

• Need special equipment

This UV coating is mostly applied with rollers; therefore, it can only be applied to flat objects. Application by spraying can be done, but it will require solvent to dilute the coating according to the ideal viscosity for the spray process. This condition, of course, will make the finishing cost expensive and no longer economical. Spray application will also produce dust spray that will pollute the environment. Dust spray from UV coatings is considered more dangerous than other coatings because it contains monomers that potentially trigger cancer in humans.

- Relatively limited for simple finishing

Because of its limited application method, this coating is only suitable for simple finishing. Complex finishing with multi-step applications cannot be accommodated by this coating. The finishing antique or special finish with many effects is very difficult to do with this coating. The handwork and art process are very limited due to their application. 

• Limited use on flat shapes

This coating also cannot be used for products with complex shapes. The drying process of this coating requires a UV oven, which needs a closed room. UV ray is considered harmful since it can trigger cancer in humans who are exposed to them; therefore, the UV lamp oven must be tightly closed. UV lamp ovens for flat objects is relatively easy to make since it is considered two-dimensional. But for products with complex shapes, it's quite difficult to be built. A large room with very high lamp energy is needed to build an oven for 3-dimensional objects.

Currently, many portable UV lamp ovens have been made that can be directed to illuminate certain parts. However, the use of this tool is still not easy to do for complex products.

Uses of the UV coating

• Wood Flooring

UV coating is the best coating to finish the wood flooring. Almost all finishing processes on modern wooden floors or engineered wood flooring are done with UV coating. UV coatings provide the properties needed for floor finishes, such as being strong, hard, durable, and low cost. Many other finishing materials, such as UV stain, UV filler, UV Putty, and UV primer, are available to support the UV finishing process. Many models and types of machines are invented to accommodate the UV finishing process. 

• Walls, flat panels and furniture components

UV coating is also widely used for finishing on flat panels for various purposes, such as house walls, doors, or components for modern furniture. Panel boards for kitchens or home cabinets are most often finished with UV coating. Furniture with simple and knockdown models also widely uses the UV coating process.

Things to consider in using UV coating

• Volume of work

The UV coating application process requires special equipment, a series of roller machines for coating application, UV lamp ovens for the drying process, and sanding machines (wide belt sanders) for the sanding process. In a complete finishing system, the machine for the UV finishing process consists of a series of several machines that work sequentially, each of which works automatically. All of these series of machines are big machines that could be considered expensive stuff. Investment in this machine is a cost that must be considered when you decide to use the UV coating system. 

When the machine runs, it needs to be set up and arranged to do the object in the same size and shape. When the shape and object change, then the machine needs to be rearranged. Make sure you have enough volume of products to make sure you can run the machine efficiently. Calculate the volume of work, the benefit, and compare it with the investment cost you need to run the UV coating process.

• Shape of goods

The finishing process with UV coating is in principle more suitable for products with flat shapes, such as floors, panel boards, and flat components. The products with 3-dimensional shapes such as tubes, circles, or posh are not suitable for UV coating finishing. Although technically UV coating can be diluted and applied by spraying, it is not efficient and will be costly.

Make sure you know the type and shape of the product you are going to process and make sure it can be run with a UV coating machine

• Quality demands of the finishing.

UV coating will indeed produce a hard and strong film layer, but it cannot produce a perfect appearance. The film layer from UV coating is generally not smooth, even like the film layer produced by PU, melamine, NC coating, or other coatings that are applied by spraying. Therefore, finishing with UV coating is not very suitable for finishing the product that wants maximum beauty of appearance. To produce a good finish, UV coating is usually used together with other coatings, such as NC, or PU. The UV coating in the base, followed by PU or NC coating as the last layer, is the better option to make a high-beauty finish.