Food-Safer FinishesComments (0)
This article is from Issue 25 of Woodcraft Magazine.
Picking the right finish is more about watching the clock.
Thanks to writers and editors (like me), woodworkers worry about “food-safe” finishes more than poolside moms fret about kids snarfing down chicken salad sandwiches then diving into the deep end. To address this matter, let me start off by making one point loud and clear:
All drying oils and varnishes sold for finishing wood are non-toxic and food safe when fully cured.
At this point, we could leave the next page blank for you to sketch your next project. However, there’s a second, often overlooked, point that you can’t ignore, when you give a well-crafted wood gift and watch the recipient’s nose crinkle the second they unwrap the box: Some finishes take a lot longer than others to become fully cured and food safe.
While trace amounts of finish or solvent don’t pose a serious health risk, the smell can ruin the taste of certain foods. This “smell-factor” is almost as important for non-food related projects such as pens, jewelry boxes, and blanket chests, where you don’t want any lingering solvent odor.
Finding a food-safe finish is easy; finding one that looks good and smells OK within a tight time frame (or won’t knock you out when working in a small basement shop) is trickier. The following information about oil and film finishes, and the accompanying chart, will help you find the right balance between ease of application, protection, good looks, and curing time. Use it all to pick the best finish for your next project.
Fine print and the FDA
Want to know the facts? Oils, varnishes, and oil paints all contain metal driers in order to cure. These driers appear on an approved product list drafted by the FDA. So-called “food-safe” finishes use the same driers as those that don’t put “food-safe” on the can.
While most finishes have not been tested for food contact (that stamp requires pricey per-batch purity testing) because they all use materials from the same list, they’re just as safe for food contact as those that claim “food-safe” on the label. (Some of the “safest” finishes aren’t even on the list. Mineral oil is sold in drug stores as a laxative. Wax and shellac are used to coat certain foods and medicines.)
“When you can’t smell the finish, the finish is safe.”
It’s a good rule of thumb, but not entirely accurate. What smells “safe” for one person may still stink to another. Also, heat can release solvent many weeks after the piece passed the initial sniff test. To be safe, allow extra curing time whenever possible, or select a faster-drying finish.
Oils are thin, but defend from within
The advantage to oil finishes is that they sink in. In addition to enhancing the look of the wood, oils provide decent water and stain protection as long as the surface receives regular care and feeding. Luckily, this is an easy wipe on/wipe off affair.
Mineral oil doesn’t dry, but because it’s easy to apply and odorless, it’s a favorite for butcher-block countertops, cutting boards, and other projects finished the night before. Many woodworkers like mixing it with beeswax for additional stain-fighting resistance and to give surfaces an extra glow. Natural polymerizing, or drying oils, such as tung and walnut, perform better, but these natural products require about two weeks to cure. Until they do, you’ll need to put up with a distinctively nutty aroma.
Salad bowl finishes are the food-minded entry in the oil/varnish category. Like the rest, they provide some of the color enhancement afforded by oils, coupled with a protective varnish film.
While these thin film finishes cure quickly, you’ll still need to provide some curing time. If you can’t give it at least a week, you might want to consider mineral oil if the piece will see regular food contact, or shellac if you’re looking for a nice shine.
Films protect the perimeter
Film finishes provide better surface protection, but are more likely to chip, peel, or crack, allowing water and other potential stains to find a direct path to unprotected wood. For that reason, films might be fine for knife or breadboxes, but less suitable for cutting boards that might see knife action and then be rinsed in the sink.
Shellac may not seem as tough as some other finishes, but in our tests, fresh-mixed shellac provided slightly better moisture and stain resistance than mineral and tung oil. The only downside is its alcohol solubility. While perfect for drawers and furniture, shellac isn’t recommended for use on tabletops, for instance, where folks might forgo the coaster.
Lacquer outperforms shellac, but you’ll need to fight the fumes during the finishing process. It’s also prone to scratches, making it less suitable for pieces that might see heavier use.
In the film-finish arena, polyurethane is king. However, while fast-drying polys might feel dry in a few hours, curing takes longer. It can take weeks for the solvent to work through a multi-coat finish. So if you’re planning to apply more than a light spray coat, apply this finish before starting on other last-minute gifts.
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