There are many commercial brands of finish that are labeled as food safe. These range from many products that are called anything from ‘salad bowl finishes’ to ‘butcher block oils’, etc. In reality, the vast amount of finishing products and oils are actually already food safe, as long as they are allowed to cure properly.
Tried and True Choices
I believe it is best to go with what has been proven safe and effective in the past. There are basically two types of finishes, film-forming and penetrating. While film forming finishes (also called coating finishes) offer better protection initially on the wood surface, eventually the finish tends to chip, peel and crack. These finishes include lacquer, varnish and shellac.
Penetrating finishes, which can be in the form of both drying and non-drying oils soak into the wood and help repel moisture and liquids for a brief period of time, such as when washing the item or during the preparation of food. They are easy to apply, but are not as durable as the film forming finishes and need to be reapplied periodically in order to renew the finish. Reapplication is quite easy, however, and it is possible to patch worn out places without resulting lap marks around the edges.
Since most of the information I have found seems to favor drying and non-drying oils as food safe finishes, I will focus on those two options and give a few facts about each.
Drying oils penetrate the wood and harden the material. Included in this category are linseed and tung oil. They can also be referred to as wood sealers and are very satisfactory finishes for wood surfaces. Not only do they reduce the absorption of moisture, but they tend to make the surface easier to clean and a bit more resistant to scratches.
Pure tung oil can be difficult to apply, and requires many coats to offer good water resistance. The drying time is quite long, usually between 24-48 hours on average, but this depends on the porosity of the wood. It will take three to four coats to achieve a waterproof surface, and you can lightly sand or buff the surface with extra fine steel wool between coats.
Raw linseed oil is another alternative as a drying oil finish. This should not be confused with boiled linseed, which contains metallic driers. The main problem in using raw linseed oil is that it can take weeks, if not months to dry, making it impractical for most finishes.
Non-drying oils are oil finishes that simply penetrate the wood. There are two types of non-drying oils – vegetable oils and mineral oils and are both very suitable for finishing surfaces which are to come into contact with food.
Vegetable oils used for finishing include olive oil, corn oil, peanut oil and safflower oil. They are edible and are usually a good choice for finishing wood utensils. Walnut oil is particularly suitable for this purpose, as it is less likely to turn rancid. Although this condition is not considered hazardous, it may impart an undesirable odor or flavor on the items. For this reason, it is important that treated utensils be allowed to dry thoroughly for several weeks before use.
Mineral oil is a non-drying oil made from petroleum. It is colorless, odorless, tasteless and entirely inert. Mineral oil will not turn rancid after time as many vegetable oils eventually do. It appears to be the non-drying oil of choice for this reason.
Application of these oils is simple, although you do need to periodically reapply them in order to maintain the finish. You simply wipe on a thick coat of mineral oil and allow it to absorb into the wood. After several minutes, simply wipe the excess oil away with a soft cloth. Allow several hours to a day in between coats. Keep building up coats until your desired finish is achieved. It is difficult to make a mistake applying this type of finish.
I also found that applying this finish using a ‘wet on wet’ technique gave a very pleasing result. I first sanded my wood, graduating up to 600 grit. I saved the 600 grit sandpaper that I had used in the initial dry sanding and for the first two or three coats of mineral oil, I used that piece of sandpaper to apply the oil and work it into the finish. The tiny particles which were left on the sandpaper helped work the oil into the pores and gave it a beautiful finish. The wood developed a wonderful luster and the end result was striking.
A final application that I want to discuss is the mixture of beeswax or paraffin wax with mineral oil to offer a slightly more durable finish. You simply melt the wax in a double boiler over hot water with the mineral oil (using a 1 part wax to 5-6 parts oil ratio). Be sure to use low heat and stir the mixture frequently. When the mixture is blended, pour it into a jar and cool until it solidifies. To apply the soft paste, wipe it on with a soft cloth, allow it to dry a bit and wipe the excess off. You may also want to apply it as a liquid or warm the surface with an old iron to help improve the absorption of the wax. As with any finish of this type, however, you will need to maintain it and reapply often to give decent moisture protection.
Source by Sheila Landry