Coating for wood furniture finishing

Coating is the finishing material that performs to make a film layer at the finishing. Clear coat, or clear coating, is a coating in the clear form (no color). The coating is made of a mixture of resin that can produce a hard film layer when it dries. The dry film coats and protects its substrate underneath, makes a smooth surface, and also forms the finishing look. Clear coatings are modern finishing materials that work as the varnish and shellac, they have the function to form a film layer in the finishing. If shellac or oil may be considered as the traditional finishing material, the clear coating is the modern material that mostly produced by finishing materials manufacturers with the modern technology and production system.

This material is available in many types and increasingly developing in accordance with the development of finishing materials technology. According to its function, the clear coat can be classified into: top coat, flow coat, sealer and wash coat, You can find more information about it in our previous post : wash coat, sealer and top coat

The name and type of the clear coatings are determined by the resin in the mixture, which will also determine the properties and the character of the coat.

PU finish for dining table

 

Here are the types of clear coatings that are the most widely used in the wood finishing industry:

• Nitrocellulose clear coating, lacquer

It is a clear coating with the nitrocellulose resin as its major ingredient. It is a type of clear coating that is very easy to handle and use in the wood finishing industry. The clear coating can dry fast at room temperature, easily to be resolved and revised if necessary. The dry film produced films have the highest clarity compared to the other types of clear coatings. This material can produce a finish with a clear, beautiful appearance with a thin, natural-looking film finish.

This clear coating is very popular because it can produce the most beautiful finishing appearance. It is suitable for use in the furniture finishing that puts priority on the appearance, such as indoor furniture products, especially for high-end furniture.

The disadvantages of this material are a relatively low resistance to scratches, heat, and solvent. This clear coat also has a low resistance to ultraviolet light; its film layer will yellow after a certain time. Find it more in our previous article: Lacquer finish for wood furniture

•  Acrylic clear coating,  butyrate clear coating, non-yellowing lacquer

It is a clear coating made from a mixture of butyrate and acrylic resin as its main ingredients. The film layer result has a higher resistance to the ultraviolet light, so it won’t be yellowing as the NC clear coating film. This material has properties similar to the NC clear coating. It is quick to dry at room temperature, can be resolved, and produces a natural and thin film. The resulting film does not turn yellow, but it is not as clear as the NC clear coat.

This material is suitable for use in finishing the colors for white and light colors when the yellowing of the film layer will disturb the appearance of the finishing color.

As well as a lacquer finish, the coating film has a relatively low resistance to solvents, scratches, and heat. See our article: butyrate clear coating

• Acid curing clear coating, melamine, conversion varnish.

It is a clear coating that contains amino resin therein. The resulting film cannot be resolved, is hard, strong, and has high resistance to heat, scratch, and solvent. It is widely used for furniture finishing on products that require a more powerful film layer, such as dining tables, kitchen cabinets, and furniture products for hotels or bars. This clear coat consists of 2 components: the clear coating and the hardener. Both materials must be mixed with a certain composition when it is applied.

This material will release a toxic formaldehyde gas in the drying process. The resulting film layer can be thicker than the lacquer finish. The application that is too thick tends to produce a thick film, resulting in a plastic-looking finish. Find it more in our previous article: Acid curing clear coating

• Precatalyzed clear coating.

It is the development of acid curing or conversion varnish. This material is similar to the acid curing but is packed in one-component form, so it can be handled more easily.

The resulting film is stronger than the lacquer finish, more resistant to the solvent, but still less strong compared with the 2-component acid curing. Find it more in our article: Precatalyzed clear coating

• Polyurethane clear coating.

It is a clear coating that is made of urethane resin as its main component. The polyurethane that is most widely used for wood finishing is the 2-component polyurethane coating. This clear coating produces a strong and hard film coating that has a high resistance to solvents, heat, and scratches. It also can produce a thicker film compared with the NC or AC clear coating. The PU clear coating is suitable for the finishing on furniture products that require high durability, such as hotel furniture, bar furniture, and even wood floors. This material is also widely used for the process of finishing on furniture products that require a thick and high-gloss film finish.

This material consists of 2 components: the coating material and the isocyanate as the catalyst. The isocyanate as a hardener will spur the cross-linking reactions to form the dry and hard film layer. This clear coating is relatively difficult to handle since it has a long drying time. It also releases isocyanate gas, a toxic fume, in the drying process. See our article : Polyurethane coating for wood furniture

• UV clear coating

It is a clear coat that dries with a polymerization reaction that is spurred by the ultraviolet light. This material will produce a very strong and hard film. Its film layer has a very high resistance to scratches, heat, and solvent. This material is relatively expensive and somewhat difficult to be applied on furniture since it requires an UV lamp oven that only works effectively for the flat panel.

This clear coat is more widely used for flat panels. For the flat surfaces, the roller application will result in a high efficiency of material consumption. The UV clear coating is most widely used for finishing the wood parquet flooring. See our article: UV coating for wood finishing

• Water-based clear coating.

It is a clear coating material that uses water as its main solvent. This material became very popular because it is the finishing material that is considered environmentally friendly. Many people like this material for the finishing process of the furniture product, replacing the thinner base clear coating.

Water-based clear coating will produce a film layer that is stronger than NC but still less strong than the AC or PU or UV coating. This material uses water as its main thinner. It makes the drying process run slowly and is highly affected by the environment's humidity. When the weather is dry and hot, the drying process can be very quick, but when the environment air is wet and humid, the drying process will be very slow. See our article: water-based coating for wood furniture

• Polyester clear coating.

It is the clear coating with the polyester resin as its main component. The coating consists of 3 components: the coating, hardener, and thinner. They must be mixed immediately before its application since it has a very short pot life. It is relatively difficult to handle and very rarely used in the wood finishing industry. This material is able to produce a very strong finishing layer with high thickness. The material is mostly used in the finishing process to make a clean, high-gloss finish with a thick layer of film. See our previous article: polyester coating for wood furniture