Staining and Finishing Wood by Rex Rothing
There are many different products on the market for staining and finishing wood and several different methods of application. So many choices that an average person could be quite confused in making a decision of which to use and how to apply a finish on a woodworking project. Reading this article should help you to decide which finish and application is best for your project.
Begin by choosing the wood color your project requires. It is my opinion that clear finishes on natural wood look better than colored stains. A stain is a color change and perhaps a sealer, but not really a finish. Stains can make light woods look darker or a different color but this can sometimes opaque the real beauty of the natural wood. Stains can be mixed to match an existing wood and stains can be used to make a color more uniform over an area of color variations in the natural wood. In general, I would say, if you want it to look like mahogany, oak, or maple, then it is best to start by using that wood rather than building with maple and then trying to stain it like mahogany. You might save some money by working with less costly woods like pine or poplar, but the time, materials, and effort trying to make the pine look like a more costly wood such as mahogany may not be equal to or much less than just paying for the mahogany to start with. Furthermore, pine stained to look like mahogany will never look like mahogany since the grain is different. Pine looks good as pine, maple as maple, walnut as walnut, so you see a clear finish is the best. However, sometimes a stain becomes necessary for certain projects.
To stain wood, first test the stain on a sample of the same wood. It is best to start off with a thinned light coat and add little by little until the correct color intensity is achieved. It is much easier to make wood darker than it is to lighten it. You can mix stains of the same brandname and type to achieve different colors. Light stains look best on light woods and darker stains on darker woods. Stains can be applied by spray, brush, or wiped on with a rag. Spraying is not practical for most people. Brushing is good for carved or rough surfaces but rubbing in or wiping on with a rag is most likely the best way to achieve uniform results. Disposable gloves are used to protect the hands from being colored. Follow the directions on the label. In general, you work quickly in one direction with the grain trying not to stop too long or overlap the areas and thus avoiding uneven spots. Gell stains are good because they do not show lap marks. A combination of brushing on and wiping off is often useful for uneven surfaces such as raised panel doors or routed mouldings. Stir the stain often to keep the color uniform. Work quickly to get the stain on evenly and then leave it alone and let it dry completely before applying final finish coats. To prevent a blotchy look on soft woods, a pre-stain sealer or a coat of shellac should be used before staining.
Choices of finishes for wood include oil based or water based polyurethanes, enamels, epoxies, and paints, oils, waxes, lacquer, shellac, sealers, and varnishes. Emmision controls and regulations are changing for volatile organic compounds so water based finishes are becoming more common in the market place. These water based finishes are also becoming easier to apply and more durable in their use and therefore, may be the best thing for some people and projects. Care should be taken to keep from mixing finishes that are not compatible (read the labels). And one should take care to choose the finish appropriate for project's use and location. For example, oil maybe the best for a cutting board while paint may be the best for a patio chair. Tung oil finish may be best for interior furniture while exterior spar urethane or marine varnish may be best on a boat. Paint is appropriate for houses and deck stain and sealers are for decks. Read further to learn how the different finishes are commonly used and a few details or opinions about which finish is best for which purpose.
Oils, such as danish oil. teak oil, walnut oil, mineral oil, lemon or orange oil, olive oil, tung oil, or even old transmission fluid can be used to keep wood from weathering and drying out. Food grade oils are used for kitchen utensils, cutting boards, and bowls. Petroleum based oils are used for marine woods and exterior woods. In either case, the soft oil finish is temporary and needs to be refreshed every few weeks or months depending on its use and exposure to sunlight and cleaning products. These oils leave the wood looking flat with little or no gloss.
The tung oil finish is my personal favorite finish but it is often misunderstood. Real tung oil would be like the soft oil finishes discussed above, while tung oil finish is combined with thinners and hardeners to create an oil that dries hard and builds up a surface finish with several coats that is impervious to water, alcohol, and cleaning solvents. This is a great finish for interior woods. It wipes on easily, dries quickly, and builds up with several coats to a durable finish free of brush marks, drips and runs. Tung oil finishes come in low or semi-gloss, and high gloss mixtures.
Sanding sealer is used under a tung oil, polyurethane, or varnish finish. This sealer is a product that binds with the wood fibers and hardens them so the surface can be sanded off very smooth. Sanding sealer costs less than top finishes and it dries quickly so it can save a lot of time by keeping the first several coats of a finish from soaking into the wood repeatedly.
Shellac is also a good sealer and stain blocking coat that can be applied under a polyurethane, tung oil, or varnish finish. Shellac in three coats is also a good interior wall or cabinet finish. It may not be so durable on table tops and working surfaces as other finishes but it is easy to brush on and it dries quickly. It is good for interior vertical surfaces and as an undercoat to keep sap and mineral stains in wood from bleeding thru a paint or varnished finish.
Lacquer is a finish that dries quickly, has heavy fumes, and is best sprayed on by professionals in a controlled spray booth. Brushing lacquer is available and it makes a good finish if you work at it.
Wax can be applied as a finish for interior woods. Small boxes, picture frames, treasure chests, and other craft items look good with a simple wax finish. The wax is applied by rag and buffed out after drying for a low gloss sheen. A wax finish can be renewed by cleaning with furniture polish and a soft cotton rag. Wax comes in dark or light colors.
Enamels come in oil or water based formulas. There is nothing wrong with good old-fashioned paint, whether it is clear or colored it can be a durable and useful finish on many household items. Good interior or exterior paints can be used whenever ease of maintenance is desired. All clear finishes require regular maintenance, however, a good exterior paint, properly applied, could last 15 or 20 years.
Epoxy is usually a two part mixture which hardens in several hours. This finish is used as an encapsulation for undercoating marine installations. The epoxy does not have ultra-violet inhibitors so it needs to be coated over with a good exterior finish, either paint or varnish.
Polyurethane for interior or exterior, or spar (marine) urethane are normally brushed on and level themselves out as they dry over a slow period of time. This thicker application and slower drying time allows for more drips and runs to occur as well as more dust and bugs to stick to the finish. For this reason, these finishes are best applied in a controlled environment whenever possible.
Varnish is somewhat softer than urethane or polyurethane so it can be sanded smooth between coats. Good captain's varnish will contain plenty of ultruviolet light inhibitors. You can read the labels to determine the correct brand. Most marine woods need to be varnished 7 to 8 coats before being put in service and then maintained with more coats semi-annually.
To apply a finish cut the sleeve off on old t-shirt and cut the top off an empty milkjug, or use a brush and a plastic container to hold some material while you spread it evenly with the brush or rag. You use a rag for thin oil or wipe-on finishes and you use a brush for thicker paints, epoxy, and polyurethane finishes. Paints can be thinned and wiped on with a rag for a "whitewashed" or "pickled" look. Most products require sanding in between coats. After sanding, or scuffing with a nylon scrubbie, the surface is cleaned with either a tack cloth or a rag dampened with mineral spirits. Most finishes require 3 or 4 coats to build up and look good. Most finishes will stick to anything clean, dry, and sanded.
