Applying a finish to a butcher block table presents some unique challenges for the do-it-yourselfer. If the table is to be purely decorative, then it can be finished using any of the standard wood finishes, i.e., oil, varnish, shellac, etc. Because part of the appeal of the butcher block table is the pattern of the woodblocks that make up the top, paint is seldom used as a finish. But if the table is to be used for food preparation, the finish chosen for the top should be non-toxic and flavorless.
Since only the top of the table will be in contact with the food, the legs and sides can be finished with any type of finish. If done carefully, there will be a little variation in appearance between the top and sides. But if the consistency of appearance is important, the entire table can be finished with any of the products that we are going to discuss.
There are two basic types of wood finishing products; on the wood (varnishes, shellac, wax) and in the wood (tung oil, mineral oil, etc.). Although either of these can be used for a butcher block table the oil finishes have the advantage of soaking into the wood so they are less likely to be damaged by cutting instruments and less likely to transfer to food that comes in contact with the surface. All of the finishes that we will discuss are non-toxic so contamination of food is not an issue but damage by knives certainly is. Stains that change the color of the wood generally contain toxic components and so should be avoided.
There are several choices in oil finishes that will give good results on a butcher block table. Mineral oil is a clear product sold in pharmacies as a laxative. It can be wiped or brushed on and allowed to soak in. Several coats may be applied and the excess wiped off. Gentle buffing will yield a soft sheen. Another product that can be used is raw linseed oil.
Do not use boiled linseed oil; it has added chemicals that should not come in contact with food. Read the label carefully. Raw linseed oil has a slight yellow color that actually can enhance the look of some woods. Tung oil and walnut oil are also excellent choices for non-toxic finishes. However, make sure that the label says PURE tung oil or PURE walnut oil. Products labeled as oil finishes or oil varnishes have added ingredients that are not suitable for use near food. Read the label carefully if you have doubts.
One significant advantage of oil finishes is that they can be renewed by just applying more oil. No sanding or removal of the old finish is required. Just apply a new coat, let it dry for 15 minutes or so, and wipe away the excess.
There are two on-the-wood products that are non-toxic. The first is wax. The most common types are carnauba (made from palm trees) or beeswax. These are available as paste waxes and are applied in a light coat with a cloth to the surface. After drying, the surface is buffed with a clean dry cloth to give a satin sheen. Wax can be applied over an oil finish to provide extra protection and has the advantage of oil finishes in that it can be renewed by merely applying another coat.
The other non-toxic on-the-wood finish is shellac. Shellac is a natural resin secreted by an insect native to India and Thailand. It is harvested in the jungles and then refined to provide several grades of shellac. Many woodworkers mix their own shellac but the process requires some knowledge and experimentation. Luckily premixed shellac is available at paint and hardware stores. It can be applied by brush or using a soft, lint-free cloth.
Several coats may be applied but allow each coat to dry overnight before applying the next. Shellac that is old will lose its ability to dry so make sure that you use fresh products. Wax can be applied over the shellac for added protection. Since the shellac is on the surface of the wood, it is subject to damage from knives and other kitchen utensils and will soon show the effect of use. Renewing the surface requires sanding to provide adhesion for the new coating and, for this reason; oil finishes are preferred for this type of application.
Material Safety Data Sheets (MSDS) are available for most finishing products. Along with the label information, they can guide you in selecting a non-toxic finish. But remember, hazardous ingredients that comprise less than 1% of the product do not have to be listed so unless the label clearly says non-toxic, don’t assume that it’s safe. If you have questions, contact your supplier or the manufacturer.Material Safety Data Sheets