Furniture has wood as its base material. Finishing is the penultimate process in the manufacture of wooden furniture. It gives gloss and other desirable characteristics to the wooden surface. Finishing closes unwanted pores on the wooden surface. Therefore, it eliminates the possibility of a breeding ground for the bacteria.
There are different types of varnishes and oil-based coatings available in the market. Polyurethane and lacquer fall under this category. However, they are very different from each other.
Polyurethane vs Lacquer
The main difference between polyurethane and lacquer is that polyurethane is a thick coating that forms a protective layer over the wooden surface, whereas lacquer is a thin coating that provides protection by penetrating into the surface.
Polyurethane is a varnish that is composed of microscopic resin molecules. It can be oil or water-based. It provides a very protective finish to the wooden surface.
Lacquer is a popular wood coating that produces a hard and durable finished surface. It dries by the solvent evaporation process, and its drying rate is very fast.
Comparison Table Between Polyurethane and Lacquer (in Tabular Form)
| Parameter Of Comparison | Polyurethane | Lacquer |
|---|---|---|
| Thickness of Coating | It is a thicker coating. | It is a thinner coating. |
| Surface Penetration | Forms a layer over the surface. | Penetrates into pores. |
| Drying Time | It takes a longer time to dry due to the thickness of the coating. | It takes less time to dry as the coating is thin. |
| Multiplicity of Coats | Multiple coats cannot be applied simultaneously due to longer drying time. | Multiple coats can be applied simultaneously due to a shorter drying time. |
| Applied Using | It is applied using a paintbrush. | It is applied using a spray. |
What is Polyurethane?
Polyurethane is a varnish that contains chains of resin molecules. It forms a protective layer over the wooden surface and doesn’t penetrate deeper. The polyurethane coating is highly durable. It provides protection from water and other chemicals. It is applied using a paintbrush.
There are three types of polyurethane coatings. These are oil-based, water-based, and water-based oil-modified. The oil-based polyurethane coating is very durable. It forms a hard film in a few coats. However, it takes a longer time to dry than water-based coats.
The water-based polyurethane coating gives a crystal-clear gloss to the wooden surface. It dries quickly, but more coats are needed. The wooden surface should be properly ventilated while applying the coating.
The water-based oil-modified polyurethane coating dries to become a tough oil-like film. It dries very quickly. Polyurethane coating can be removed using a plastic scraper or sandpaper.
What is Lacquer?
Lacquer is a wood finish that dries by a process called solvent evaporation. It is less durable when compared to polyurethane coatings. The lacquer coating penetrates into the wood and prevents the breeding of harmful bacteria by clogging pores. Since it is thinner, it also dries very fast. A spray is used to apply lacquer coating.
There are many types of lacquer coatings. These are shellac-based, urushiol-based, nitrocellulose, acrylic, and water-based lacquers. Shellac is obtained from the secretions of the lac bug. It produces a red pigment for surface finishing.
Urushiol-based lacquers use oxidation and polymerization along with evaporation, to set on the surface. Urushiol is a mixture of phenols and proteins. This lacquer dries very slowly. However, the coating is very strong and resistant to acids and other chemicals.
Nitrocellulose lacquers contain nitrocellulose, which is obtained from the nitration of cotton and cellulose. They provide a hard, flexible, and waterproof finish.
Acrylic lacquers use the acrylic polymer. They dry extremely fast. Also, there is no need to further polish the surface as enough shine is imparted by this lacquer.
Water-based lacquers dry very quickly, and are also less hazardous. However, they are not suited for coating external surfaces. The lacquer coating can be removed from the surface by using a solution of denatured alcohol and lacquer thinner.
Main Differences Between Polyurethane and Lacquer
Polyurethane and lacquer are wood finishes. They add gloss to the wooden surface.
The main differences between the two are :
- Polyurethane coating is thicker, whereas lacquer coating is thinner.
- Polyurethane simply acts as a protective layer, whereas lacquer penetrates deep inside.
- The polyurethane coating takes more time to dry, whereas the lacquer coating dries quickly.
- Multiple coats of polyurethane can’t be applied simultaneously, whereas multiple coats of lacquer can be applied quickly.
- Polyurethane coating is applied using a paintbrush, whereas lacquer coating is applied using a spray.
Conclusion
Wood finishing is not only important for visual appeal, but also for smoothening the surface. It is the final process of wood manufacturing, and takes a share of 30% of the total cost. Polyurethane is a thick coating. It is highly durable and protective, but dries slowly.
Lacquer is less durable as compared to polyurethane. It is thinner, penetrates deeper, and dries very quickly. Nowadays, the automation of wood finishing products is being adopted. The product is traversed through a train of processes, all automatic.
There are several approaches used in the manufacturing process. In the Hangline approach, wooden items are hung on a conveyor belt. The Towline approach uses rotating mobile carts that carry large wooden products. Both approaches use a sprayer for liquid finishes.
It is estimated that the wood coatings market will grow to $ 11985.8 in the year 2025. The increase in development is causing an increased demand for modern furniture. However, the VOCs that are used in the production of wooden furniture are harmful to the environment. Therefore, there is a need for new sustainable innovations in the wooden manufacturing industry.
References
- https://www.thisoldhouse.com/painting/21018327/all-about-polyurethane