This article only addresses wood finishes and not paint or similar type products. Ultrus™ Prospector® Knowledge Center[i] has many articles that are specific to paint. As a related article, read Considerations for Developing Wood Coatings[ii], by Ron Lewarchik.
One of the program session tracks (Tuesday April 30, Session 4: Wood Coatings) at the just-completed American Coatings Conference in Indianapolis had 6 papers from a variety of companies and topics. Two of these were “Low-VOC TEA-free high solids PUD’s for wood” presented by Israel Skoff of Lubrizol, and “Novel acrylic emulsion for matte coatings without matting agents” presented by Senthil Kumar Rengasamy of BASF. Review the slides of these and the other presentations if you can.
Wood furniture finishes, or simply wood finishes, is a process developed to shield wooden artifacts and furniture from environmental injury. Without the proper finish, the wood may crack, dry, swell (exposure to moisture), and deteriorate. However, although the primary goal of each type of wood finish is to add a protective layer, it can also help improve the aesthetic attraction of the wood. People are looking for attractive coatings that are especially warm.
Technologies for Wood Paneling, Siding, and Flooring Finishes. Considerations for Developing Wood Coatings; March 20, 2015 by Ron Lewarchik; Ultrus™
Types of Wood Finishes
Usually, there are two primary types of wood finish, including penetrating and surface finish. Each type results in a unique appearance and protection, making it necessary to choose the right type of finish.
Penetrating Finishes
Penetrating wood finishes offer a more natural look as they enter deep into the surface of the wood. You may have to use a cloth to add a protective layer of wood oils to ensure better sheen and surface penetration.
Linseed Oil
Linseed oil, which comes from flax plant seeds, is an easy to apply wood finish, also with a brush or cloth. However, curing may take longer. It soaks into the pores, resulting in a shiny appearance. Linseed oil enhances natural appearance. A downside is that it darkens with age, but it is ideal for firearm stocks, surfboards, etcetera.
Tung Oil
Obtained from the nut or seed of the tung tree, Tung oil is one of the most universal penetrating finishes. It is an environmentally-friendly wood finish and relatively safe when completely cured. It is ideal for boat decks and floors, and results in a light satin look with a slight golden tint. It generally is applied with a cloth or brush.
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Cedar Oil
Known as cedarwood oil, this wood finish has a characteristic woody odor. Cedar has a natural resistance to insects, disease, and rot resulting from exposure to moisture or water, which makes it desirable in exterior applications particularly on facades and siding. It has a warm, hand rubbed and natural appearance which is also ideal for polishing and furniture. An undesirable trait is that it becomes light silvery gray when fully weathered.
Danish Oil
It is a mixture or oil (usually tung oil or boiled linseed oil), varnish, and thinner. Danish oil offers better surface protection than plain oil wood finishes. It is relatively easy to apply and moderately durable. It does enhance the natural appearance of wood, and it’s typically used for wooden utensils and handles. It results in a buffed to matte finish or gloss, and is applied using previous methods cited.
Surface Finishes
Surface finishes are applied on the top of the wood to create a protective layer. This type of wood finish makes an outstanding choice for furniture and materials that are exposed to much news and therefore wear and tear.
Shellac
Shellac wood finish looks very attractive on wooden objects made from walnut, fine veneer, and mahogany. However, it is not durable and dissolves in water and solvents like alcohol. In recent years, water based shellac has been developed but it is not anymore durable then alcohol based shellac. Shellac results in a fine finish that accentuates the natural grain of the wood. It can be rich orange to super blonde, and can be used on a variety of substrates. We are discussing wood finishes here, but shellac does an excellent job of smoke and fire stain suppression.
Lacquer
Lacquer is a combination of different shiny wood finishes. Lacquer is used in many cases when it really isn’t known what the finish is and really can be a misnomer. For example, you can find lacquer wood finish based on shellac, nitro cellulose, and urushiol, among others. Usually, the drying process involves solvent evaporation, resulting in a hard and durable finish. The appearance is dull, medium to high gloss. Ideally used for wooden furniture such as cabinets, doors and shelves. Nitro cellulose was the most popular furniture finish for many years. It has a distinction of being able to rewet the coated substrate if a mistake is made in finishing. Water based lacquers have suffered in this regard.
Varnish
Varnishes are generally a more complex coating, as it is a clear and transparent wood finish that usually comprises drying oil, resin, and thinner or solvent. Varnished wood finishes are based on lacquer, alkyd, polyurethane, and acrylic, shellac, and resins, among others. Varnish like lacquer, is used interchangeably for many finishes when either the person using the word, knows what the finish is or not. The finish is glossy or high gloss and it is used primarily on floors cabinets and furniture. Application often requires spray equipment, but it also can be applied by roller or spray. Since they generally dry quickly, brushing requires quite a bit of skill.
Wax
In writing this article on wood coatings, it is almost inappropriate to include wax, but it is a coating although not in the traditional sense. Usually, it is primarily carnauba. However, you can find wax finishes with practically any type of wax currently. Wax furniture finish is easy to apply and offers some abrasion resistance. But it is not durable and requires frequent reapplication. As in several of the other finishes, nano silica can be included to provide some abrasion and wear resistance without sacrificing any gloss loss.
Polyurethane
Polyurethane wood finish is durable and water-resistant, thus offering excellent protection. It can offer a warm and amber tone to the wood. However, it can be difficult to repair damage to it. There are many polyurethanes, and polyurethane acrylics that can be used. The choice of finish and also the polyurethane type, will depend on the application and the required resistance to sunlight, as well as other factors. The appearance can be natural and is generally used in high use area that can tolerate cost.
Dye
Like waxes, dyes are finishes but Fall into the category of surface treatment. Wood dyes are frequently powders that you can mix with alcohol or water. The dye particles penetrate deep into the wooden surface, so you don’t need to use a binder. Dyes enhance natural appearance and are suited for furniture. Vibrant and deep colors can be achieved and multiple coats will also provide a depth or change of color.
Stain
Stains consist of a pigment, carrier, and binder. The carrier helps insert the pigment into the surface and binder makes it attach. Stain wood furniture is often, made from oak and ash and the stain makes it look very attractive. It enhances the natural appearance for indoor and outdoor uses.
[1] Raw Material and Ingredient Paint & Coatings – Prospector (ulprospector.com)
How to Choose A Wood Finish for Your Home? A Complete Guide (gharpedia.com)
Chemical Testing and Analysis Services for Consumer Products | UL
[1] Considerations for Developing Wood Coatings (ulprospector.com)
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