The Definitive Guide to Food Safe Wood Finishes

As a seasoned wood turner and woodworker from Raleigh, North Carolina, with over fifteen years of professional experience crafting wooden items, I’ve extensively explored the world of wood finishes. My work, which you can see in my portfolio, has always prioritized both beauty and functionality. For pieces intended for food contact, the choice of finish is paramount. This article dives deep into the realm of Food Safe Wood Finishes, drawing on my hands-on experience with many products available today. I aim to provide a comprehensive overview, discussing the characteristics of each finish, their performance, and my recommendations for the best options. Furthermore, I will share insights into the preparation and application techniques I’ve honed over years of finishing utility wood items.

Understanding Wood Finish Types

With the exception of shellac, the majority of food safe wood finishes we will discuss fall into the category of penetrating finishes. These finishes work by soaking into the wood fibers, offering protection from within. Shellac, in contrast, is a film finish. It creates a protective layer on the surface of the wood, much like polyurethanes and lacquers. Wax, in the context of food-safe finishes, largely remains on the surface as well. However, waxes alone are not sufficient as a primary finish due to their lack of durability.

Penetrating finishes share a similar application method. You generously apply the finish to the wood surface, allowing it time to absorb, and then remove any excess. This process is repeated over multiple coats to build up the desired level of protection. While penetrating oils excel in ease of application, cost-effectiveness, and ease of repair and maintenance, they generally don’t match the robust durability of film finishes like polyurethanes, lacquers, or conversion varnishes. However, for food safe wood finishes, penetrating oils are often the preferred choice due to their natural and non-toxic qualities. You can find more information on various types of woodworking finishes in another article I wrote.

What penetrating oils might lack in ultimate durability, they more than compensate for in ease of use, affordability, and the simple process of repair and upkeep. These factors are particularly important when considering items designed for food service or preparation that will see frequent use. Durability, in this context, refers to a finish’s ability to withstand scratches, dents, and exposure to acids and other substances commonly found in a kitchen environment. The most durable wood finishes often boast a high solids content in their resin components, which are frequently derived from petrochemicals. These resins require solvents to maintain a liquid state for application, and many of these compounds carry some level of toxicity.

The “Food Safe” Philosophy and Natural Wood Finishes

This brings us to a critical point: the definition of “food safe” in the context of wood finishes. One school of thought posits that any finish, once fully cured, becomes food safe. Even nitrocellulose lacquers, with their associated solvents like lacquer thinner, are considered food safe under this definition, assuming complete curing and the absence of off-gassing.

Waterborne finishes are often touted as having lower toxicity compared to petrochemical-based finishes. They are composed of water, acrylic/polyurethane resins, and a catalyst to facilitate curing. While less toxic than options like conversion varnish or traditional lacquer, they still contain synthetic components with potential toxicity.

Personally, I lean towards the philosophy that food safe wood finishes should be entirely organic and derived from natural sources. It remains challenging to definitively assess whether trace amounts of toxic compounds from manufacturing processes might leach into food over time. While the risk might be minimal, I prefer to err on the side of caution, especially given the constant wear and tear that utility items endure, which can compromise film finishes.

Function Dictates Finish: Choosing for Utility Items

Utility wood items like salad bowls, serving bowls, cutting boards, and utensils are inherently high-wear items. They are far more susceptible to scratches, dents, and cuts compared to furniture or decorative wood pieces. These imperfections become particularly noticeable on film finishes, and their visibility is amplified by glossier sheens. The painted hollow form pictured above illustrates how sanding scratches are highly visible on a film-like paint finish, demonstrating a similar effect to scratches on glossy film finishes.

Considering the nature of utility items, the most crucial finish characteristics, in my opinion, are a low sheen, ease of repair and maintenance, and straightforward application. This naturally leads us to favor penetrating oils, unless you are prepared for the constant sanding and refinishing that film finishes on heavily used items would require. Furthermore, for handcrafted woodwares intended for sale, maintaining a natural, easily repairable finish is often more appealing to customers. Therefore, I advocate for naturally occurring food safe wood finishes over chemically produced penetrating oils for these applications.

Exploring Types of Food Safe Wood Finishes

Shellac: Is It Food Safe?

Let’s begin with shellac, the sole film finish on our list of food safe wood finishes. Shellac is a resin secreted by the female lac bug. These insects deposit the resin on trees in regions of India and Thailand, using it to create protective tunnels on tree branches. When these branches are harvested, resin and all, they are known as “sticklac.”

Sticklac undergoes processing and purification to produce shellac flakes in solid form. These flakes come in a variety of tones, from garnet to amber to super blonde. Super blonde shellac, the lightest in color, is produced when lac insects feed on the Kusum tree (Schleichera oleosa).

Shellac flakes are soluble in denatured alcohol. A liquid finish is created by dissolving flakes or powdered flakes in alcohol, resulting in a “pound cut.” The pound cut refers to the concentration – for example, a 2lb cut consists of 2 pounds of flakes dissolved in 1 gallon of alcohol. The viscosity of the finish increases with the proportion of shellac. Liquid Shellac typically has a shelf life of about one year, which is why mixing fresh cuts per project is often preferred. Dry flakes, however, have an indefinite shelf life.

Naturally occurring shellac contains a small amount of wax (3-5% by volume). Most shellac flakes sold are dewaxed to prevent adhesion issues with subsequent top coats. Shellac is frequently used as a seal coat in various finishing processes.

Shellac in Wood Finishing

My primary use for shellac is as a seal coat on furniture, especially when using colorants like stains or dyes and spray-applying a finish. For food safe items, I generally avoid colorants, as the woods I select often exhibit rich natural variations that I want to highlight. Thus, I typically opt for penetrating oils. However, in my early woodworking days, I did use shellac as a primary finish for some pieces.

Shellac dries rapidly to a high-gloss sheen and has a higher solids content than Danish oil. It is generally recommended to apply shellac in thin coats, using a 1 or 2-pound cut, as heavier ratios may not adhere as effectively. Multiple thin coats yield better results than fewer thick coats. Shellac, like lacquer, “melts in,” meaning each subsequent coat partially dissolves the previous one, creating a unified layer.

Traditionally, shellac is applied using a pad, a wad of cotton cloths. A small amount of shellac is applied to the pad, which is then used to apply the finish to the wood surface, typically in a circular motion, unlike the back-and-forth motion of brushing. Brushing shellac is also common, and may be preferable over padding for flat surfaces like cutting boards, as opposed to curved surfaces like bowls.

So, is shellac a food safe wood finish? Yes, once the alcohol has fully evaporated and the finish is completely cured. While I appreciate shellac for certain furniture applications, its characteristics are less ideal for food safe items. Its drawbacks include lengthy application times and a tendency to show scratches easily. Shellac is also susceptible to water marks; condensation rings from glasses can leave noticeable marks. However, its ability to “melt in” makes it relatively easy to repair.

Mineral Oil: Food Safety and Limitations

Mineral oil is a petroleum derivative, technically not a natural oil, but it is considered food safe. Commonly sold in pharmacies for use as a laxative, it can also be found in hardware and woodworking stores, often labeled as butcher block oil. White oil, paraffin oil, liquid petroleum, and baby oil are all forms of mineral oil under different names (baby oil typically includes added fragrance).

Mineral oil’s primary advantages are its colorless, odorless, and tasteless nature, its low cost, and its resistance to rancidity. As a penetrating oil, it’s applied using a wipe-on, wipe-off method. Its colorless quality is a significant benefit; most penetrating oils tend to impart a yellowish tint to wood. Mineral oil allows the natural wood color to shine through more accurately, which is particularly desirable when working with woods that have varied tones or multiple species.

However, the benefits largely end there. Mineral oil is not a waterproof food safe wood finish, nor is it durable. It offers minimal protection against scratches and evaporates relatively quickly. While most penetrating oils aren’t known for high durability, mineral oil ranks near the bottom in this regard. The most significant drawbacks are its poor water resistance and rapid evaporation. Bowls finished with mineral oil often require re-oiling monthly. In my early sculptural pieces, where I used mineral oil as a base coat under lacquer, I encountered microbubbles forming in the finish after curing. Overall, I consider mineral oil a poor choice as a primary food safe wood finish.

Linseed Oil: Navigating the Options

Linseed oil comes in three main categories: Raw Linseed Oil, Polymerized Linseed Oil, and Boiled Linseed Oil. Derived from flaxseed pressings, raw linseed oil has a long history in wood preservation. Its primary disadvantage is its extremely slow drying/curing time, which can range from two to ten weeks depending on environmental conditions. While natural and technically one of the food safe wood finishes, its impractical drying time makes it less desirable.

Boiled Linseed Oil (BLO) is commonly found in hardware stores. Despite its name, BLO isn’t actually boiled in the traditional sense, or at least boiling isn’t the primary factor speeding up its cure time today. Instead, it contains added drying agents to accelerate curing, addressing the slow drying of raw linseed oil. However, these additives, which often include Japan drier, naphtha, and heavy metal salts, render BLO non-natural and not food safe. Therefore, Boiled Linseed Oil is off our list of food safe wood finishes.

Polymerized Linseed Oil emerges as a viable food safe wood finish option. This type of linseed oil undergoes boiling in the absence of oxygen, the “polymerization” process. Polymerization significantly reduces drying time compared to raw linseed oil. This heat-based process, unlike the addition of chemical dryers, preserves the oil’s natural, food safe qualities.

Chemically, the heat processing alters the fatty acid chains in linseed oil, facilitating quicker double bond formation. This accelerates polymer chain crosslinking, thus speeding up the curing process. For a deeper dive into the chemistry of linseed oil polymerization, this article provides excellent in-depth information.

Using Polymerized Linseed Oil for Wood Utility Items

Tried & True is a prominent brand of polymerized linseed oil. While my direct experience is primarily with BLO, polymerized linseed oils share a similar application method: wipe on, saturate, and wipe off excess.

Tried & True recommends allowing the oil to sit on the wood surface for an hour before wiping and buffing, with a recoat time of 24 hours. Compared to commercial oil blends like Danish Oil or Tung Oil finishes, this is a relatively long saturation period. The manufacturer suggests two to three coats, with potentially more for high-wear surfaces. Additional coats won’t increase sheen but will enhance durability.

Customer reviews of Tried & True are mixed. Some users report positive experiences, while others have encountered issues, such as the finish being too thick initially, requiring heating to reduce viscosity before application, as well as reports of weeping and extended curing times. While I haven’t personally used Tried & True, I suspect these issues might stem from batch-to-batch inconsistencies in manufacturing. Overall, I consider polymerized linseed oil a reasonably good choice among food safe wood finishes.

Food Grade Cooking Oils: A Viable Finish?

Food grade cooking oils represent another category of potential food safe wood finishes. I know some older professional bowl turners who used olive oil for many years. However, most have transitioned away from cooking oils as better alternatives have become available. With the wide variety of cooking oils now on the market, are they a practical option?

The primary argument against cooking oils is their tendency to go rancid upon exposure to oxygen. Secondly, cooking oils, similar to raw linseed oil, primarily wet the surface with minimal curing. Depending on the type of cooking oil, some film formation might occur, but the curing time is likely very long.

I often suggest to customers that they occasionally rub their bowls with olive oil as a maintenance step. It’s the most readily accessible option for homeowners to refresh the luster of their woodenware. However, I don’t consider it a primary finish, as superior options exist. Frequent use and washing of utility items help mitigate rancidity concerns with cooking oils.

Fractionated Coconut Oil has recently gained popularity and is easily obtainable. It’s coconut oil that has undergone processing to remove long-chain fatty acids, which are the components that oxidize most quickly and lead to rancidity. Thus, fractionated coconut oil is resistant to going rancid. Some products and DIY recipes combine fractionated coconut oil with beeswax, often marketed for cutting boards. I haven’t used these blends personally, but they might hold promise as maintenance products. Overall, the consensus is generally negative regarding cooking oils as primary food safe wood finishes.

Pure Tung Oil: A Natural and Durable Choice

Tung oil, also known as China oil or Chinawood oil, is a natural drying oil extracted from the nuts of the Tung tree, native to China and other parts of Asia. It has a long history of use, primarily valued for its water-resistant properties. Tung oil dries harder than linseed oil, contributing to greater durability. Often, there is a trade-off between hardness and overall durability.

Similar to linseed oil, “tung oil” encompasses several product types. Pure tung oil is naturally slow curing, though not as slow as raw linseed oil, taking approximately 15-30 days for a full cure. Beyond pure tung oil, there are tung oil blends, often labeled “Tung Oil Finish,” which contain resins, dryers, and other additives to accelerate curing. Polymerized tung oil, like polymerized linseed oil, is heat-treated to enhance curing speed by altering polymer chain bonding. It’s crucial to note that not all tung oil products on the market are food safe wood finishes. Always carefully read labels and ingredient lists to understand what you are purchasing.

Applying Pure Tung Oil

The key to finishing with Pure Tung Oil is to saturate the wood grain until it can absorb no more finish. The exact process varies depending on wood density and age. Most manufacturers recommend initially thinning pure tung oil with a solvent (like mineral spirits or citrus solvent) in a 1:1 ratio as a general starting point. Pure tung oil is quite viscous, and thinning aids penetration and curing. For denser woods that absorb finish slowly, increase the thinning ratio.

Conversely, for more absorbent woods, use a less diluted or even unthinned finish. Apply successive coats every half hour or so until the wood no longer absorbs oil. This saturation process can take up to half a dozen coats. Once saturated, wipe off all excess oil. Pure tung oil dries to a matte sheen.

For a second wave of application, repeat the saturation process, again using a 1:1 oil-to-solvent ratio. Multiple thin coats are preferable to fewer thick coats, as with shellac. Remove all excess tung oil after the final soaking. The oil absorbed into the wood pores will gradually oxidize and form the protective finish barrier. Drying continues over the next one to two weeks, with full curing taking approximately 2-4 weeks.

Walnut Oil for Wood Finishing: A Modern Favorite

Walnut Oil Finish is a more recent entrant to the market, gaining popularity in the last 15 years or so. I first encountered it around 2007 when finishing a butcher block countertop. To my knowledge, Mike Mahoney, a professional bowl maker, was instrumental in bringing it to market, though this might be anecdotal. Regardless, his brand, Doctor’s Woodshop, and Andrew Pearce are the primary brands available. Andrew Pearce is the newest of the three and likely sources from the same primary supplier. Doctor’s Woodshop and Andrew Pearce Walnut Oil are readily available on Amazon.

Walnut oil finish differs from walnut cooking oil due to heat treatment. This heat treatment denatures proteins that cause allergic reactions in some individuals. I also believe it aids in oil polymerization, resulting in faster oxidation compared to cooking oils. The type of walnut oil used for finishing has a high pH and a higher concentration of linoleic acid. Walnut oil naturally contains both linoleic and linolenic acid, omega-6 and omega-3 fatty acids, respectively. As mentioned earlier, oils with higher linoleic acid concentrations tend to exhibit better drying oil characteristics.

Similar to polymerized linseed and tung oils, walnut oil finish is a drying oil. It penetrates the wood grain, reacts with the wood surface, and forms a hardened barrier. The high linoleic acid content likely contributes to better penetration and less rapid surface film formation compared to polymerized linseed oils, potentially resulting in greater finish depth. Tung oil, with its longer cure time, may not exhibit this issue as much. Application is similar to linseed and tung oils: saturate the wood surface and wipe off the excess.

Due to oxidation and fatty acid composition, walnut oil does not become rancid like cooking oils. Another advantage is that walnut oil tends to discolor wood less than linseed or tung oil. Linseed and tung oils often impart a stronger yellow cast, which can intensify with age, while walnut oil exhibits less yellowing. Higher concentrations of linolenic fatty acid appear to contribute to yellowing. Lastly, walnut oil is less viscous than polymerized linseed or tung oils, eliminating the need for heating or dilution.

Mike Mahoney sources his oil from Northern California, and I suspect the other brands do as well. Doctor’s Woodshop is based in Oregon, and Andrew Pearce’s product descriptions closely mirror Mahoney’s. Andrew Pearce is an East Coast brand (Vermont), suggesting they might all source walnut oil from the same region, possibly even the same supplier. Commercial walnut trees in Northern California are almost exclusively English Walnuts (Juglans regia), originally Persian walnuts with numerous varieties developed. It’s conceivable that oil from Black Walnut (Juglans nigra), which has higher concentrations of both linoleic and linolenic fatty acids, might perform even better as a drying oil. However, Black Walnuts, native to the U.S., are more challenging to process and are not commercially cultivated to the same extent as English walnuts.

Despite being a relatively recent introduction to woodworking finishes, walnut oil has a long history. Records of its use date back to the Renaissance and possibly earlier. Many Old Masters (Vermeer, Da Vinci, Van Eyck, etc.) preferred walnut oil over linseed oil for mixing paints, primarily due to linseed oil’s yellowing tendency. During this era, painters commonly formulated their own paints and paint mediums. There are some chemical parallels between the drying processes of oil-based paints and drying oils used for wood finishing. This article on walnut oil in paint making offers a fascinating look at its history.

Beeswax and Carnauba Wax: Finishing Touches

Beeswax and carnauba wax, while technically food safe wood finishes, are inadequate as standalone finishes. However, waxes frequently serve as the final step in a finishing process, often used for polishing or rubbing out. Honeybees produce beeswax from wax glands, secreting small scales of wax, particularly active in spring or after swarming. Beeswax is the material they use for building comb and cell cappings. The lightest beeswax (almost white) is generally the freshest, often used for honey storage comb. Brood comb tends to darken the wax to a deeper yellow. Older comb also yellows over time.

Carnauba wax (also known as palm or Brazil wax) is derived from the waxy leaves of the carnauba palm, native to Brazil. It’s a hard, brittle wax available in various purity grades with widespread industrial applications. Carnauba wax is often blended with softer waxes like beeswax for easier application in woodworking. Waxes enhance wood shine and offer some protection against moisture and UV light. Harder waxes tend to be more durable but also harder to apply.

Apply waxes using the “karate kid” method: wax on, wax off. The degree of rubbing depends on the wax amount and pliability. Formulations range from liquid waxes to hard, brittle waxes. However, liquid waxes are generally not food safe, like automotive waxes. I prefer products with a consistency similar to softened butter, typically blends of waxes with a significant oil component. With these paste waxes, excess left on the surface can create a firm, sticky film.

Both beeswax and carnauba wax are natural products, though often formulated with other ingredients and relabeled. Many blends combine beeswax, carnauba wax, and oils like orange or mineral oil. Some formulas may contain toxic components, so reviewing ingredient lists is crucial.

My Method: Finishing Utility Items for Longevity

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For items requiring a food safe finish, I prefer walnut oil (Mahoney’s). I believe it’s among the best in its class, although tung oil and polymerized linseed oil also yield excellent results. For a final top coat, I apply a blended wax for added protection, detailed below.

While I primarily create bowls, this finishing method is suitable for any food safe item. All pieces are sanded to 220 grit before oil application. I prepare bowls on the lathe, sanding in both directions and sanding as much of the bottom as possible. A small tenon remains, preventing complete sanding at this stage. Once off the lathe, I remove the tenon, hand-scrape tool marks, and hand-sand the bottom center to 220 grit. A vacuum chuck would eliminate this step, but I consider it a luxury. Finally, I burn my signature on the bottom and hand-sand to enhance its clarity, all up to 220 grit.

Here’s my food safe finish application process: I apply two coats of walnut oil, allowing ample soak time before wiping off excess. I apply one coat per day. After the second coat, I pre-wash the items to raise the grain and break down some of the finish. Ideally, I would immerse small objects in a tub of walnut oil, letting them drip dry and wiping excess later. However, for larger pieces and current production levels, a dedicated dunking tub is impractical. Immersion yields superior results.

I hand-wash pieces with mild soap and warm water, as I do with dishes. Towel dry thoroughly and allow them to air dry overnight. After drying, the wood will feel slightly fuzzy due to raised grain. Pre-washing minimizes grain raising later, especially after items are in customer hands. Raised grain occurs when wood fibers lift after wetting, creating a fuzzy surface, particularly noticeable on coarse-grained woods like oak and ash.

While some incorporate grain raising into surface preparation, pre-washing is crucial for utility items due to frequent washing. Spraying bowls with water during lathe sanding is common, but I find pre-washing more effective in preventing future grain raising.

After pre-washing and complete drying, knock down the raised grain by sanding with 400 grit sandpaper. I use Norton 400 grit. I cut quarter sheets into thirds and fold strips into thirds for hand sanding. Expect oil residue buildup on sandpaper, but it’s minimal. This step dramatically improves the tactile quality of the finished piece.

Following grain knockdown, I apply a third coat of walnut oil. Immersion is ideal if possible. Oil absorption will be slower at this stage, so allow soak time and wipe off excess. The final step is applying a blended wax of walnut oil, carnauba, and beeswax to enhance luster and further seal the wood. This utility paste wax has a softened butter consistency due to the high walnut oil content.

I apply two wax coats, one per day. Mike Mahoney sells Walnut Oil Wax, but I blend my own. Several similar products are available. When blending your own, higher carnauba wax content makes the wax stiffer, requiring more walnut oil for paste consistency. I prefer a creamy, easily flowing wax.

My wax batches last a long time, so I’m still refining mixing ratios. My last ratios were approximately 1:2 carnauba to beeswax, melted in a double boiler. Melt and then add sufficient oil for desired consistency. I believe I used a 3:1 oil-to-wax ratio last time. Adding oil to melted wax speeds cooling and creates wax chunks requiring further blending. Next time, I plan to warm the oil first and dissolve the wax in the hot oil. Reflecting on it, I’m unsure why I didn’t do that last time.

Recently, I’ve noticed some shelf life limitations in my wax; it can become slightly gummy, likely due to walnut oil curing. I would experiment with reliquefying the wax blend to remedy this or simply make a fresh batch.

Once completely cooled, the wax stiffens, often needing consistency adjustment. After cooling, add more oil to restore a creamy consistency. Expect larger wax chunks needing breakdown for a uniform paste. The second mixing should create a stable, long-lasting wax with minimal need for further adjustments.

Maximizing the Lifespan of Your Food Safe Wood Finishes

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In recent years, my diet shift towards leafy greens has meant daily salad consumption and bowl washing. Using the finishing method described, I rarely need to recondition my bowls. While the luster may not be as intense as a newly finished bowl, they hold up well, and I haven’t found them dull enough to require reconditioning. Grain raising has also been minimal.

For overall care, hand wash wood items and towel dry them immediately. Avoid leaving wood items wet. Do not microwave wood bowls as it can cause surface or catastrophic cracking. Dishwashing is also not recommended. A light coat of walnut oil or paste wax after washing is acceptable but generally unnecessary. Excessive wax buildup is not a concern with regular washing.