Deciding a finish for a project that will come into contact with food always gives me pause to think. I certainly don’t want to put a finish on a bowl that may be harmful to the people who use it. So I set out to learn a little more about finishes that are recommended as being safe for use on bowls, cutting boards, utensils, and even children’s toys.
Before getting started though, I want to discuss what I mean by the term food-safe finish. Nearly all finishes are considered non-toxic after they’re fully cured — even those that use metallic drying agents containing cobalt, zirconium, zinc, or manganese. So in some respects, all finishes are “food-safe.”
Despite this, a lot of woodworkers (myself included) are still reluctant to use a finish containing potentially harmful chemicals on an item intended for food contact. The reasoning here is that it’s better to be safe than sorry.
Fortunately, there are several finishes available that are free of toxic chemicals. These are what are typically referred to as “foodsafe” finishes. Most of these are either oils, waxes, or a combination of the two. Here’s a look at some of the more common ones.
COOKING OILS. Vegetable oil, corn oil, peanut oil, and olive oil are often suggested as simple, foodsafe finishes. And although all of these can be used as finishes, I generally steer clear of them for one main reason. The problem with most cooking oils is that they break down quickly and turn rancid when exposed to air.
WALNUT OIL. A lesser known oil for finishing is walnut oil. Walnut oil is a natural drying oil. It’s often sold in grocery stores as a salad oil. But when sold as a finish (through woodworking suppliers), it’s usually been polymerized by heating. This polymerization causes the oil to dry quickly, without the use of metallic driers or solvents.
Unlike vegetable oils, walnut oil doesn’t turn rancid and has a pleasant odor. It’s easy to apply, but doesn’t offer a lot of protection and requires frequent reapplication.
RAW LINSEED OIL. Raw (or pure) linseed oil is pressed from flax seed. Unlike boiled linseed oil, raw linseed oil contains no metallic driers or solvents. So although it’s a drying oil, it will take much longer to dry. It imparts a warm color to most woods and is easy to apply.
TUNG OIL. Pure tung oil is extracted from the nut of the China wood tree. Unlike linseed oil, tung oil won’t darken the color of the wood. It’s a good choice for lighter colored woods, or when you want to show off the natural color of the wood. Tung oil also provides good water resistance.
Tung oil is used as the base for several commercial finishes that have added driers and solvents. These are usually labeled as “tung oil finishes,” rather than pure tung oil. So be sure to check the label of the product before you buy.
MINERAL OIL. As a derivative of petroluem, mineral oil is a finish that’s in a class of its own. It can’t be classified as a natural oil, like the others I talked about. But it’s completely safe for contact with food. And it’s available at pharmacies and grocery stores, where it’s sold as a laxative. You’ll also find it in paint or hardware stores sold as butcher-block oil.
Mineral oil is a non-drying oil. It will remain “wet” long after it’s applied. It’s also odorless, colorless, and tasteless, so it’s a good choice if you’re concerned with the finish imparting a flavor to food.
BEESWAX. Produced by honey bees, beeswax offers a slightly more water-repellant finish than most oils. It can be melted and mixed with mineral oil or raw linseed oil to create a pleasant-smelling and easy-to-apply finish.
BLENDED FINISHES. Most of the finishes discussed so far are sold in a pure, unblended state. But you’ll also find some commercial finishes that are simply a blend of mineral oil or wax, often mixed with a scented oil for fragrance.
SALAD BOWL FINISH. A few finish manufacturers offer products labeled as “salad bowl finish.” Only by reading the manufacturer’s material safety data sheet (MSDS), can you know what’s in these finishes. Most of them are primarily an oil/ urethane mix. But they also contain solvents and some even contain metallic driers. However, the trade-off is that these finishes offer greater protection to the wood than the naturally derived finishes.
None of the food-safe finishes mentioned here offer the same level of protection as a traditional varnish or lacquer. But they’re all fairly easy to reapply whenever necessary. (See the box below for information on how to rejuvenate a wood bowl.) And they may also offer something that other finishes don’t — peace of mind.
Food-safe finishes are also a good choice for use on toys for young children.
How-To: Restore a Wood Bowl
No matter which food-safe finish you choose, repeated washing and everyday wear and tear will eventually take a toll on the finish.
If you have a wood object that needs restoring, there are number of products that you can use to clean it. For a bowl that’s badly stained or has mildew, you may need to sand the surface until you reach bare wood. And if there is a hardened finish on it, you’ll need to use some wood stripper first.
But if the bowl is just a bit grungy, I like to use natural a cleaner like lemon juice or vinegar to cut through the grease and grime. Combine this with pumice and a nylon abrasive pad to remove the built-up grime and finish.
Once you have a clean, dry bowl, you can apply any one of the food-safe finishes mentioned above. Finally, to help extend the life of the finish, avoid putting the bowl in the dishwasher.