Wood finish has been utilized for centuries to serve both protective and ornamental functions. The choice of finish varies depending on the desired appearance and intended use of the wood, be it for a chair, floor, ceiling, or decorative molding.
Wood finish in restoration
Every day in the field of restoration, a range of wood varnish is employed to revive floors, doors, windows, and decorative elements, bringing them back to their previous splendor.
Wood restoration has been performed by John Canning & Co. on various projects, such as the Cosmos Club in Washington D.C., the Mark Twain House in Hartford, CT, the Pennsylvania State Capitol, the Sterling Memorial Library at Yale University, and Gasson Hall at Boston College.
Two categories of wood finish: Penetrating and surface
The wood finishes employed in modern times closely resemble the ones utilized in the 1700s or even before that. Wood finishes can broadly be classified into two categories: penetrating finishes and surface finishes.
Penetrating finishes
Penetrating finishes are capable of deeply seeping into the wood, thereby achieving a highly authentic appearance that prominently showcases the wood’s grain and character. These types of finishes usually require multiple applications in order to sufficiently build up the thickness of the overall coating. Examples of penetrating finishes include Rubbing Oil finishes. When it comes to wooden floors, oil finishes are commonly utilized owing to their ability to provide a natural and rustic aesthetic.
Oil finishes, such as Tung Oil, have been used for centuries in various applications, including furniture and wooden utensils, due to their food-safe and non-toxic properties. Tung Oil, derived from the seed of the Tung tree, is widely recognized as the most favored oil finish and has a long historical usage in ancient China.
The goal for the Cosmos Club Ballroom floor was to conserve the existing floor, fix any damages, and apply a protective and low-maintenance finish that would recreate the original appearance. To achieve this, Waterlox Interior Tung Oil in a high gloss sheen was employed to replicate the shiny surface seen in old pictures.
Surface finishes
The remaining popular finishes, including shellac, wax, copal, polyurethane, and varnish, essentially remain on the surface of the wood.
Shellac
Resin produced by the lac bug, native to India, is used to make shellac. By the early 1800s, shellac started gaining popularity in the United States as it was imported from India. However, it is mainly utilized for decorative purposes rather than protective ones due to its vulnerability to water and chemicals, causing it to wear down easily.
By thinning it with denatured alcohol and drying quickly, shellac offers the advantage of being able to revive its hardened finish by applying denatured alcohol over the surface, thus rejuvenating it.
Wax
During the period from the mid-1700s to the 1800s, wax enjoyed great popularity. Although various types of wax can serve as a protective layer similar to varnish, beeswax was the preferred choice among the early New Englanders because it was abundant in the colonies. While it may not be as long-lasting as other varnishes, beeswax can be easily applied to any kind of wood. Therefore, it is commonly utilized for flooring and furniture, providing a more reflective appearance when compared to oil finishes.
Wax coatings offer two significant advantages: they can be easily removed using a cloth and paint thinner, and they allow control over the level of sheen. The level of sheen achieved can vary from a dull, low sheen to a highly reflective, polished sheen, depending on the extent of buffering performed after application.
Polyurethane
Polyurethane, a chemical formula akin to liquid plastic, was initially developed by Dr. Otto Bayer (1902-1982) during the outset of World War II. Its purpose was to safeguard masonry, wood, and metals, including war machines and airplanes. Its exceptional durability and waterproof nature make it highly effective in providing protection.
Polyurethane is now employed in a wide array of items we encounter regularly, including chairs, tables, cars, clothes, appliances, and even wall insulation. When utilized as a wood finish, it is commonly found on cabinets, doors, furniture, and floors. When contemplating the use of polyurethane, it is important to be aware of two factors: it tends to create a hard and brittle surface that may peel off over time, and the varnish film will eventually acquire an amber hue.
Varnish
Varnish is made up of oils, resin, and solvents and combines surface and penetrating finishes. Its history is closely connected to the history of arts and industry, as it effectively shields artifacts with a suitable protective coating. Moreover, varnish provides ideal UV protection for outdoor furniture and decking.
The gathered samples were analysed to determine the original stain and varnish used on the south wall of the PA State Capitol.
The old varnish was removed, and a water-based aniline dye stain was applied. Then, Pittsburgth Rez-Varnish with a satin sheen was used to match the sample. The north, east, and south walls were repaired, along with the floor on the south side and the caps to each pilaster.
Oil finish
Oil wood finishes enhance the appearance of raw wood by replacing the natural oils that dry out over time and augmenting the inherent grain. Unlike superficial layers, oil finishes penetrate the wood, resulting in a richer and more translucent appearance.
There are two kinds of oils that can be utilized – drying and non-drying oils.
When drying oils come into contact with oxygen, they undergo a transformation from a liquid state to a solid state. Linseed oil is the most frequently utilized drying oil.
Non-drying oils, such as vegetable and mineral oils, can be utilized for the treatment of wood and can be applied to both interior and exterior surfaces.
Wood dye
Wood dye has the ability to either match the current color of the wood or modify the color of the surface. Dyes, which are colorants, are dissolved in solvents such as mineral spirits, alcohol, or water. The process of wood dyeing is comparable to that of cloth dyeing.
Wood dyes have the ability to produce changes in color without obscuring the grains. They can be applied using a brush, sponge, or spray gun. These finishes, known as wood dyes, are available in both water-based and oil-based forms.
Wood stain finish
The wood stain finish alters or enhances the color of the wood and makes the grain more noticeable. It is employed to improve the woodwork’s color and to create consistency when there are variations in the wood’s appearance.
Wood stain finish works best when the color of the stain is darker than the color of the wood.
Wood stains come in various colors and the end result relies on how many coats are applied to the wood surface. The wood stain itself does not offer protection to the wood, which is why it is necessary to apply a final coat of wood finish after applying the wood stain in order to safeguard the wood.
Lacquer
Lacquer is a type of finish that dries quickly, contains solvents, and is thinner in comparison to other finishes. It has the ability to penetrate the wood, provide nourishment, and enhance the wood’s grain. The application of lacquer is simple and can be done with either a brush or by spraying.
Upon spraying, the lacquer evaporates and simultaneously acts as a wood preservative. However, the lacquer finish is susceptible to scratching and water exposure can lead to damage. Ultimately, lacquer provides a glossy appearance to the wood.
Water-based finish
Water-based finishes provide a cleaner and more transparent finish compared to oil-based finishes. These finishes incorporate acrylic resin, urethane, and alkyl, and have a thinner consistency, making them quick to dry. As the water evaporates upon application, the liquid adheres to the surface. Water-based finishes give a natural appearance to the surface and are simple to upkeep.
French polish
Since the 19th century, the technique known as French Polishing has been employed to finish wood, which is widely recognized as a classic method of wood finishing. To achieve this finish, a combination of alcohol and shellac is employed. The wooden surface is then rubbed with an oil-soaked rubbing pad in order to attain this distinctive finish. French polish is renowned for providing wooden surfaces with the most glossy appearance.
Wood preserve
The purpose of using wood preserve is to prevent the wood from rotting and being damaged by insects. Wood preserve is offered in different colors and with either a matte or semi-gloss finish. Its application is specifically intended for the exterior of wooden surfaces.
After familiarizing yourself with the different types of wood finishes, carefully select one that matches your specific needs, the type of wood, and desired color. Be cautious in your choice as wood finishes that penetrate the wood are challenging to remove; thus, it is crucial to choose one that aligns with your requirements most effectively.
