The ‘natural’ alternatives

There was a time when the term ‘natural finish’ simply meant any transparent coating that revealed the organic grain and tone of the wood. Today, most people deem it to mean a product made with responsibly harvested organic ingredients rather than petrochemical ones. Natural is a subjective term, applied to unadulterated beeswax and processed products such as tung oil, linseed, or shellac. The most comfortable definition might be a finishing solution that does no harm.

In the interests of durability, kitchen and bath cabinetry is almost always coated with a manmade, chemically enhanced product. Turned objects, bespoke furniture and hardwood kitchen utensils are more likely to be the recipients of ‘natural’ finishes, in the belief that those coatings are either food-safe or ecologically sound. The concept of green, environmentally conscious finish has acquired an aspect of morality, measured as much in empirical carbon imprints as it is in emotional shades of guilt. But the truth is that almost any finish, when fully cured, is essentially food safe and environmentally neutral. Unless it has deteriorated and dissolved or flaked, or is an old lead-based paint, the health concerns from contact with a cured surface are relatively minimal. Emissions are the real measure of detriment, primarily in the manufacture and application stages before compounds turn from liquid to solid. Post-application VOC emissions are occasionally a concern, and that is true for both natural and engineered solutions. It applies to dyes, stains and sealers as much as it does to topcoats.

Natural is an absolute term, akin to the word pure. Neither concept is viable, or indeed realistic, when applied to finishing solutions. Additives such as hardeners make organic solutions work better. The quest is to find the least harmful balance because absolutely everything, even beeswax, has some environmental impact. Ask a bee.

Genuine shellac is a resinous compound of acids and waxes. It is harvested from trees where it has been deposited by the female lac bug (Kerria lacca). The insects create tunnels of secretion along branches as they feed on the tree’s sap. Different trees deliver different colors of shellac, ranging from a creamy tan to a ruddy brown. About one third of this natural shellac is aleuritic acid.

Some products labeled as shellac are chemical compounds that replicate the sheen and depth of the natural material but may contain little or no bug-based bio elements. Shellac is also used in the food industry as a glaze, which suggests that it can be food safe.

The normal method of using shellac is to dissolve hardened flakes of the resin in denatured alcohol, to create a liquid coating. It can lend color and gloss to raw, sanded wood while also sealing and providing varied levels of moisture and impact protection. Though it has been used for about 200 years in Western woodshops, it has largely been replaced by lacquer on furniture. Shellac doesn’t hold up well against alcohol, so it’s a poor choice for bar tops and counters. Poly-based coatings also require less frequent renewal. But genuine shellac is prized by many woodworkers, especially luthiers and fine furniture replicators who use a technique known as French polishing to build up enough thin layers to gain a deep gloss. A word often used to describe one optical effect of light meeting this finish is chatoyancy, or ‘cat’s eye’. It is a dynamic effect that changes with the angle of reflection, giving the wood an almost vital appearance.

Shellac should be mixed as needed, as it has a short shelf life once dissolved. Premixed shellac is available, and its usable life is quite a bit longer. One salient advantage of shellac is that it is easier than most other commercial coatings to reclaim and reuse wood thus treated.

This is a big subject. Natural beeswax offers almost no protection to wood, but it can enhance the aesthetics of wood for a while. Most other waxes are compounds containing hardeners, and they can be applied as a topcoat over other finishes to add a temporary sheen. Wax sits on the surface of sanded wood, rather than penetrating deeply. Wax can be applied and wiped off for a matte finish or allowed to dry and then buffed for a higher gloss. It requires periodic renewal to retain a sheen.

Wax comes in liquid and solid versions, the latter being less likely to contain dryers or hardeners. Some waxes are colored by the manufacturer.

Beeswax is often enhanced by the addition of carnauba wax, which is harvested from a specific family of palm trees. When mixed, these two waxes offer a tougher finish, and they can make it easier to raise a gloss that lasts longer.

There is a difference between plant and mineral based oils. Many of the commercial tung, walnut and Scandinavian oils are versions of polyurethane varnishes that have been thinned to a viscosity similar to natural oils. Plant oils have very low or no VOC impact. Some organic oils are vegetable based (olive oil being the most common) and these can turn rancid and spoil, often emitting an odor of decaying vegetation.

Boiled linseed is usually the closest one will get in the big box stores to a pure oil, but it soaks into the grain rather than constituting a topical barrier. It can help repel moisture but offers very little protection against abrasion. It is made from flax seed and gains a patina that fades over time and requires frequent renewal. Raw linseed is available, but the boiled version usually dries faster and contains additives to facilitate that.

Tung oil is harvested from tung tree seeds and has been used for thousands of years. It soaks into the uppermost cells of dry wood and cures over a few days to create a relatively impervious layer that repels moisture but adds no hardness.

Walnut oil has gained some popularity as shops search for safer finishes, but there’s a possibility that it can negatively affect woodworkers and even customers with nut allergies. Read the label carefully.

When purchasing natural finishes, including water-based coatings, watch for solvents that have been added to manipulate cure times. These may add VOC impact to a product that is being touted as natural. Some manufacturers will use fine print, so read all labels fully. The more open a manufacturer is, the more comfortable the choice.

For example, Briwax is one of the oldest and most trusted names in wax finishes, and it makes a point of being very upfront about additives. Its basic finish is a blend of beeswax and carnauba with a solvent that includes toluene to emulsify the waxes for ease of application. “Solvents are necessary in the formulation of Briwax because without them Briwax would just be a hard chunk of wax, almost unusable,” the company says on its website, briwax.com.

The Real Milk Paint Co. (realmilkpaint.com) says that its tung oil “comes without any heavy metals, additives, or distillates. Most other oils can be anything from a thinned-down varnish to polymerized tung, and most have petroleum distillates added. Ours will not build a gloss finish or heavy finish but will penetrate deeply into the wood to enhance character or wood grain, and water resistance while creating a great wood finish.”

Some manufacturers will recommend a combination treatment of natural finishes to add some protection. For example, Vinnie’s Oil (vinniesoilusa.com) says that its “surface treatment is a natural, solvent-free and non-toxic hardwax oil consisting of several different solvent-free and cold-pressed oils with different deep penetrating properties. For very exposed surfaces, a layer of Vinnie’s Wax on top is recommended.”

Hard wax oil is perhaps the most facile and satisfying of the natural finishes. Natural hard wax oils such as Odie’s Oil (odiesoil.com) don’t contain isocyanate catalysts, and they penetrate the surface like an oil but coat like a wax. Odies says its product “will reside in the surface instead of relying on a weak surface bond.”

Whatever ‘natural’ finish a woodshop chooses, the bottom line is that the customer is looking for low environmental impact, low or no health implications, and a lasting topcoat that will stand up to daily use. The romantic notion of pure organic highly protective coatings is a myth. Natural finishes will require more upkeep. But that said, they also offer some peace of mind, and most create a deep, almost tactile surface that reflects light in a way that enhances the underlying wood in ways that chemical coatings simply can’t replicate. 

This article was originally published in the April 2024 issue.