Bon Appétit: Food-Safe Finishes for Forest Products

If you’re seeking to increase the sustainability of your home, you’d be well-served by using wooden items in your kitchen or dining room. Although the environmental soundness of wood products isn’t in question, researchers at the Forest Products Laboratory’s (FPL) Durability and Protection Unit caution that before adding these products to your household’s cupboards, you should make sure that something else goes on the wood before your dinner does.

Photo courtesy of shutterstock.com

Photo courtesy of shutterstock.com

The durability and beauty of wood make it an attractive material for bowls, butcher blocks, and other items used to serve or prepare food. Unfinished wood however does not make an ideal material for food-related uses. A finish helps keep wood dry, making it less prone to check or crack, and as a result, harbor bacteria. In addition, finished wood is easier to clean than unfinished wood. Here is the rundown of the most popular finishes:

Sealers and drying oils penetrate wood and cure (dry) to form a barrier to water during use or washing. Many commercial sealers are similar to thinned varnish (e.g., polyurethane or alkyd-modified polyurethane) and drying oils (such as tung, linseed, and walnut) can also be used as sealers. Sealers and drying oils both give the wood a surface that is easy to clean and resistant to scratching. Sealers are easy to apply and cure quickly, but drying oils may require several weeks to cure.

Nondrying oils (vegetable and mineral oils) penetrate wood but do not cure. As with sealers and drying oils, they do improve water resistance, but vegetable oils (such as olive, corn, and peanut) are also food for microorganisms such as mildew or bacteria. Vegetable oils can also become rancid and may impart undesirable odors or flavors to food. Mineral (or paraffin) oil is a nondrying oil from petroleum, and because it’s not a natural product, it’s not prone to mildew or bacterial growth.

Finishes that form a film, such as varnish or lacquer, give a smooth, cleanable surface. These finishes resist staining and should perform well if you minimize their exposure to water and avoid placing them in a dishwasher. Without proper maintenance however, the finish may eventually crack, chip, and peel.

Food service items such as salad bowls and eating utensils need a finish that is easy to clean and resistant to abrasion, water, acids, and stains. Varnishes, lacquers, penetrating wood sealers, and drying oils can be used; however, varnishes and lacquers are easiest to keep clean and most resistant to absorption of stains.

Paraffin wax is similar to paraffin oil but is solid at room temperature. Paraffin wax is one of the simplest ways to finish wood utensils—especially countertops, butcher blocks, and cutting boards.

The simplest finish for wood butcher blocks and cutting boards is melted paraffin wax (the type used for home canning). Melt the wax using a hot plate or other low-temperature heat source—do not use an open flame. Brush the melted wax onto the wood. Use an iron to melt excess wax that has solidified on the surface so that it absorbs into the wood, or just scrape off the excess wax. Film-forming finishes such as varnish or lacquer can be used, but perform poorly on butcher blocks and cutting boards.

Whatever you use, make sure that the finish is safe and not toxic. Also, be sure the finish you select is recommended for use with food or is described as “food grade.”

For information on the safety and toxicity of any finish, check the label, contact the manufacturer or the Food and Drug Administration, or check with your local extension home economics expert or county agent.

May these tips serve you well, and help keep your wooden kitchen and dining room products looking sharp, clean, beautiful, and functional for years to come.

This post has been adapted from the FPL’s Wood Handbook, Wood as an Engineering Material.