Coating for the wood finishing

Coating is the finishing material that perform to make film layer at the finishing. Clear coat or clear coating is a coating in the clear form (no color). The coating is made of the mixture of resin that can produce a hard film layer to coat and protect its substrate underneath. Clear coatings  are modern finishing material, together with oil varnish and shellac they have function to form film layer in the finishing. If shellac or oil may be obtained from the home industries, the clear coating is mostly produced by the modern industry of 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 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 : wash coat, sealer and top coat

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

Pu finish for dinning table

 
Here are the types of clear coatings are the most widely used in 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 be handled and used in the wood finishing industry. The clear coating can dry fast at room temperature, easily to be resolve 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 looked 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 put priority to the appearance and such as indoor furniture products especially for high-end furniture.
The disadvantages of this material are a relatively low resistance to the scratches, heat and solvent. This clear coat also has a low resistance to ultraviolet light; its film layer will yellowing 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 resulted has a higher resistance to the ultraviolet light, so it won’t be yellowing as the NC clear coating film. This material has the properties similar with the NC clear coating. It is quick to dry at room temperature, can be resolved and produce a natural and thin film. The resulting film does not turn yellow, but not as clear as the NC clear coat.
This material is suitable for use in finishing the colors for white and light color when the yellowing of the film layer will disturb the appearance of the finishing color.
As well as 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 can not be resolved, hard, strong and has high resistant to heat, scratch and solvent. It is widely used for furniture finishing on products that require a more powerful film layer such as dining table, kitchen cabinets and furniture products to hotels or bars. This clear coat consist of 2 components the clear coating and the hardener. Both materials must be mixed with 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 tend to produce too thick film, resulted a plastic looked 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 components 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 which has a high resistance to solvents, high heat and scratches. It also can produce 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 to wood floor. This material is also widely used for the process of finishing on furniture products that require thick and high gloss film finish.
This material consists of 2 components of material the coating material and the isocyanate as the catalyst. The isocyanate as hardener will spur the cross linking reactions to form the dry and hard film layer. This clear coating is relatively difficult to be handled 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 the dry with a polymerization reaction that 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 work effectively for the flat panel.
This clear coat is more widely used for flat panels. For the flat surfaces  the roller application will result on a high efficiency of material consumption. The UV clear coating is most widely used for finish the wood parquet flooring. See our article:  UV coating for wood finishing

•   Water base 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 peoples use this material for finishing process to 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 strength then the AC or PU or UV coating. This material is used water as its main thinner. It makes the drying process run slowly and highly influenced by the environment humidity. When the weather is dry and hot, the drying process can be very quickly, but when the environment air is wet and humid the drying process will be very slowly happened. 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 consist of 3 components, the coating, hardener and thinner. They are must be mixed immediately before its application since it has very short pot life time. It is relatively difficult to be handled 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