5 Food and Child Safe Finishes that Everyone Should Know
The general consensus among finishing experts is that any wood finish is safe once it’s fully cured. Depending on the finish you use, it could be weeks to month before it is ready for use. For people who prefer not to wait, or who would prefer to use a more natural product, here is a list of food-safe finishes to try.
Tung oil is extracted from the nut of the tung tree (also known as the China nut tree), native to China and Southeast Asia. The majority of tung oils sold as “Tung Oil” are actually oil/varnish blends. If you’re looking for food-safe tung oil, there is a pure variety on the market that contains no solvents or chemicals.
Like linseed oil, tung oil belongs to the drying oil family. Drying oils evaporate when exposed to oxygen causing them to harden through polymerization. Pure tung oil will leave behind a matte finish, whereas tung oil/varnish blends leave behind a glossier surface. This happens because pure tung oil polymerizes at a much slower rate than tung oil blends, which contain additives that quicken polymerization. When pure tung oil polymerizes, it expands, leaving behind a surface that’s microscopically textured and uneven.
Pure tung oil requires many coats to build a decent finish. It’s a fairly weather resistant — more resistant to water than linseed oil, in fact — and darkens relatively little as it ages. The downside to tung oil (and all pure oil finishes) is that they are much less protective than other finishes.
Most linseed oils seen on the market are boiled linseed oil (BLO). These contain chemicals to increase the rate at which the oil dries, and are not food safe. The food safe variety is called raw linseed oil. Raw linseed oil is extracted from flax seeds, and like tung oil is a drying oil. It absorbs readily into wood fibers and creates a light surface finish that’s mildly durable and requires frequent reapplication to maintain.
Though linseed oil is a drying oil, there are quite a few characteristics that separate it from tung oil. Linseed oil has relatively low water resistance and a tendency to yellow with age, which can be an issue when used on a light wood like maple. You may be wondering, just what are the benefits of linseed oil, then?
Apart from being non-toxic, linseed oil brings out tremendous luster in wood grain. Linseed oil leaves even less of a film behind than tung oil. Think of washing a car: how brilliantly does the paint shine before the last layer of water dries? That is how you can think of linseed oil’s effect on wood.
Raw linseed oil or pure tung oil? Of these two pure oil finishes, tung oil is the better choice for most applications. It cures more quickly, is more water resistant, and doesn’t darken as much over time. But this doesn’t mean that raw linseed oil doesn’t have its uses. It’s slower drying time makes it a great choice for projects where drying time isn’t such an issue, such as with patio or garden furniture. It’s important to keep in mind that linseed oil does not protect against insects or fungus.
Though a petroleum-based distillate, most mineral oils on the market are safe for consumption. Usually mineral oil is sold in two main varieties to indicate the level of purity: food-grade mineral oil and non-food grade mineral oil. Be sure to check the label carefully before use. The best thing about mineral oil is that it is a common household item that most people have tucked away in their medicine or kitchen cabinets.
Unlike tung and linseed oil, mineral oil is a non-drying oil, which means it doesn’t cure and requires frequent reapplication to maintain. Because of this, mineral oil is rarely used on furniture. It is more often used with things like bowls, cutting boards, and items that often come into contact with food.
The most well-known and versatile food safe finish is shellac. Shellac is a resin secreted by the female lac bug (hence “she” + “lac”), native to India and South Asia. While raw shellac flakes are completely safe and edible, premixed shellac uses denatured alcohol as the solvent which can be deadly if consumed. If you don’t want to wait for the denatured alcohol to evaporate before your finish is harmless, you can easily mix your own food-safe version. Simply dissolve raw shellac flakes in high-proof grain alcohol. To read more about the uses and benefits of shellac, read our article on wood finishes for every use.
We generally think of furniture waxes as a maintenance item or secondary finish to cover a primary finish. While beeswax can be used in those ways, it can also be used as a primary finish. This is done by melting raw beeswax in a water bath and mixing it with an oil (typically linseed oil). The final product is a soft paste that can be easily applied with a cloth. Several coats produces a matte finish that’s more resistant to wear and water damage than raw linseed oil.