For centuries, wood finish has been employed for protective and decorative purposes. Depending on the desired visual appeal and the intended use of the wood, various types of finish are utilized for different projects such as chairs, floors, ceilings, or decorative moldings.
Two categories of wood finish: Penetrating and Surface
The wood finishes used today are essentially identical to the ones used in the 1700s or even before that. All wood finishes can be categorized into two groups: penetrating finishes and surface finishes.
Penetrating finishes
Penetrating finishes deeply penetrate the wood, preserving its grain and character, and creating a highly noticeable natural appearance. To achieve the desired thickness, multiple applications of this finish are usually necessary. An example of a penetrating finish is the Rubbing Oil finish. Wooden floors are commonly treated with oil finishes because they offer a natural and rustic aesthetic.
Oil finishes, such as Tung Oil, have been utilized for many centuries and are well-known for their application in both furniture and wooden utensils due to their food-safe and non-toxic properties. Tung Oil, obtained from the Tung tree seed, has a rich history dating back to ancient China.
The goal for the Cosmos Club Ballroom floor was to protect and maintain as much of the floor as possible. Additionally, any damaged areas were repaired and the floor was restored with a finish that would not only provide protection and be easy to maintain, but also give it an appearance that closely resembled the original. To achieve this, Waterlox Interior Tung Oil in a high gloss sheen was used to mimic the shine seen in historic photographs.
Surface finishes
The other common finishes, such as shellac, wax, copal, polyurethane, and varnish, primarily remain on the surface of the wood.
1. Shellac
Shellac is derived from resin that is produced by the lac bug, which is native to India. In the early 1800s, its popularity grew in the United States as it started being imported from India. It is primarily utilized for decorative purposes rather than protective purposes due to its vulnerability to both water and chemicals, resulting in easy wear.
Firstly, shellac is thinned with denatured alcohol and has a fast drying time. It is worth noting that one advantage of using shellac is that the solidified coating can be refreshed by applying denatured alcohol on top, effectively restoring it.
2. Wax
During the period from the mid-1700s to the 1800s, wax was highly favored. The early settlers in New England primarily chose to use beeswax as a protective coating because it was abundant in the colonies. Despite not being as long-lasting as other varnishes, beeswax can be applied to any kind of wood. It is particularly popular for enhancing the reflective appearance of floors and furniture, compared to an oil finish.
Wax coatings offer two significant advantages: the ability to be easily reversed and the ability to control the level of shine. Removal of wax is a relatively simple process using a cloth and paint thinner. Additionally, the level of sheen can be adjusted post-application, ranging from a dull appearance to a highly reflective polished finish. This adjustment depends on the extent of buffering performed afterwards.
Woodworkers do not favor wax finishes due to their limited long-lasting protection. Although the process of applying wax is simple, achieving the desired outcome necessitates multiple applications. Moreover, buffing is necessary after the application has been made.
Waxes can be found in liquid, solid, and stick forms and are obtained from diverse vegetable, mineral, and animal sources for wood finishes. It is possible to create them in various colors. Whether hard or soft, waxes are still softer than varnishes, not offering much protection against scratches and wear.
3. Polyurethane
Polyurethane was developed by Dr. Otto Bayer (1902-1982) at the beginning of World War II and has the appearance of liquid plastic. Its original purpose was to safeguard masonry, wood, and metals, including war machines and airplanes. This chemical formula is known for its exceptional protective qualities, thanks to its high durability and resistance to water.
Almost everything we come into contact with today incorporates polyurethane, including chairs, tables, cars, clothes, appliances, and wall insulation. When it comes to using polyurethane as a wood finish, it is commonly applied to cabinets, doors, furniture, and floors. It is important to note two aspects about polyurethane: it tends to create a hard and brittle finish that may peel off surfaces as time goes by, and the varnish film will eventually adopt an amber hue.
4. Varnish
Varnishes are the more prevalent types of wood finishes, and they can be either transparent or colored. Comprised of oil, solvent, and resin, varnish provides a tough, resilient, and safeguarding coating. Moreover, it can be applied to both the interior and exterior surfaces of wooden items.
Typically, it has a glossy finish. Additionally, it can be customized to create a satin or semi-gloss finish using flattening agents. Varnishes offer excellent UV protection, dry slowly, and provide enhanced protection when applied over dyes.
Varnish is made up of oils, resin, and solvents, combining both surface and penetrating finishes. Its historical background aligns with the development of arts and industry since varnish serves to coat artifacts effectively for protection. In addition, varnish provides ideal UV protection for outdoor furniture and decking.
The purpose was to collect samples from the PA State Capitol’s south wall in order to identify the original stain and varnish utilized.
First, the old varnish was removed. Then, a water-based aniline dye stain was applied. This was followed by the application of Pittsburgth Rez-Varnish in a satin sheen to match the sample. Repairs were carried out on the north, east, and south walls. Additionally, repairs were made on the south side floor and the caps of each pilaster.
5. Oil finish
Oil wood finishes enhance the appearance of unfinished wood by replacing the drying natural oils with crude oil, thus improving the natural grain. Unlike other finishes, oil seeps into the wood rather than forming a superficial layer, resulting in a richer and translucent look.
Two categories of oils that can be utilized are drying oils and non-drying oils.
When drying oils are exposed to oxygen, they undergo a transformation from liquid to solid state. Linseed oil is the most frequently utilized type of drying oil.
Non-drying oils, such as vegetable and mineral oils, are primarily utilized for the treatment of wood and are applicable to both interior and exterior surfaces.
6. Wood dye
Wood dye can either match the color of the wood or alter the surface color. Dyes are colorants which are dissolved in solvents such as mineral spirits, alcohol, or water. The process by which wood dye operates is comparable to that of cloth dyes.
Wood dyes, which are applied using a brush, sponge, or spray gun, have the ability to produce color changes without obscuring the grains. These finishes, whether water-based or oil-based, are called wood dyes.
7. Wood stain finish
Wood stain finish is utilized to alter or enhance the color of wood as well as to accentuate the visibility of the wood’s grains. It serves the purpose of achieving uniformity in wood appearance in cases where there may be discrepancies.
The best suitability for a wood stain finish is when the stain is darker than the color of the wood.
Wood stains come in a range of colors. The outcome will be influenced by the number of coats applied to the wood surface. However, it’s important to note that the stain itself does not provide protection for the wood. In order to protect the wood, a final coat of wood finish must be applied after the stain.
8. Lacquer
Lacquer is a type of finish that dries quickly, and is thinner than other finishes. It has the ability to penetrate the wood, providing nourishment and enhancing the wood’s grains. Applying lacquer can be done effortlessly using either a brush or a spraying method.
When sprayed, it evaporates and simultaneously enhances the wood’s durability. Lacquer finish is susceptible to scratching and water damage. It imparts a shiny appearance to the wood.
9. Water-based finish
Water-based finishes provide a less fragrant alternative to oil-based finishes, offering a notably pristine and transparent end result. These finishes incorporate acrylic resin, urethane, and alkyl, and possess a relatively thin texture that facilitates quick drying. Upon application, the liquid adheres to the surface while the water content gradually evaporates. As a result, water-based finishes yield a genuine and effortless aesthetic while remaining easily manageable.
10. French polish
The technique of French Polishing, which utilizes a mixture of shellac and alcohol, has been employed as a wood finishing method since the 19th century, making it one of the enduring and traditional techniques in this realm.
To achieve this specific finish, the wooden surface is rubbed with a pad soaked in this oil. French polish is known for providing the most glossy appearance to wooden surfaces.
11. Wood preserve
The purpose of the wood preserve is to protect the wood against decay and harm caused by insects. It can be obtained in multiple colors and with either a matte or semi-gloss appearance. It is applied to the outside of the wooden surface.
