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Safe, Chemical-Free Wood Sealers for Raised Beds and Container Gardens

Kari Spencer is a Master Gardener volunteer and a local gardening and homesteading speaker. Her family operates The Micro Farm Project.

This article will break down five of my favorite safe, chemical-free options for wood sealing container gardens and raised beds.

This article will break down five of my favorite safe, chemical-free options for wood sealing container gardens and raised beds.

From cities and suburbs to rural environs, people are discovering the joys of vegetable gardening and the health benefits of controlling the chemicals that come in contact with their food. Many of these gardeners are opting to grow plants in raised beds or containers in lieu of traditional, in-ground row gardens.

Gardens come in constant contact with water and weather, so those that are made of wood or other porous materials require a sealant to prevent degradation. However, many conventional wood sealers on the commercial market are made with solvents and other ingredients that may release hazardous chemicals and volatile organic compounds (VOCs) into the air and your garden soil. Hazardous chemicals may find their way into the plants themselves, and ultimately into your body if you are growing edibles.

I recently came across some free wooden wine crates that were the perfect size for a small herb garden. The wood was completely unfinished and would need to be sealed. I began to research organic and natural options and found many suggestions online, ranging from low-VOC commercial products to homemade organic preparations. These products varied widely in cost, effectiveness, and ease of use.

This article will rate what I consider to be the best options based on these criteria. I will also explain how to make the homemade products and where to obtain materials.

Top 5 Natural Wood Sealers and Conditioners

  1. Raw Linseed Oil
  2. SoySeal Wood Sealer and Waterproofer
  3. Soapstone Sealer and Wood Wax
  4. Homemade Milk Paint (see several different recipes below)
  5. Homemade Beeswax and Jojoba Oil Wood Conditioner (my favorite)
Raw linseed oil is an all-natural, eco-safe wood preservative that is fairly inexpensive and can be purchased in organic forms.

Raw linseed oil is an all-natural, eco-safe wood preservative that is fairly inexpensive and can be purchased in organic forms.

1. Raw Linseed Oil

Raw linseed oil is an eco-safe wood preservative that was commonly used before modern synthetic sealers were created. It is an all-natural product that can be purchased in organic forms. It is fairly inexpensive and easily applied with a brush. The oil is very slow-drying and will take days or even weeks to thoroughly dry. If you choose to use linseed oil, be certain to purchase it in raw form, not boiled, which contains additives that are potentially toxic.

Linseed Oil Sources

  • I recommend linseed oil by Sunnyside Corp. It is natural and the price is very reasonable.
  • Linseed oil may also be available at local woodworking or craft stores.

A Note About Products' VOC Levels

The numbers cited on a low-VOC paint can are measurements taken before any additives or pigments are added, both of which can contribute to higher VOC levels than indicated. And paints can be labeled "VOC-free" if they contain less than 5 g/L.

Therefore, I was unable to verify whether or not a product is truly VOC-free, or may contain very small levels of these toxins. The individual gardener must weigh the cost and effectiveness of the product, which are both excellent, with the possibility of a minute amount of toxicity.

Made out of soybeans, the SoySeal wood sealer and waterproofer is a solid choice for sealing raised beds and containers.

Made out of soybeans, the SoySeal wood sealer and waterproofer is a solid choice for sealing raised beds and containers.

2. SoySeal Wood Sealer and Waterproofer

SoySeal is a non-toxic commercial wood sealer. According to the label, it is VOC-free and claims to provide a 24-month seal. It contains oil, water, and other ingredients.

Though it is one of the least expensive natural commercial products on the market, I did not rate it higher on the list, because I was unable to verify the exact contents of the "other ingredients."

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3. Soapstone Sealer and Wood Wax

  • Soapstone Sealer and Wood Wax, manufactured by the Real Milk Paint Company, is safe for wood that comes in contact with foods. It contains food-grade walnut oil and carnauba wax. It contains no solvents and no VOCs.
  • The product is easy to apply with a soft cloth. A second application can be made in 30 minutes, and the finish dries overnight. The product cures in 15–30 days, rendering it safe for people who have nut allergies.
  • The only drawback to this product that I can detect is cost, which is the highest amongst the products recommended in this article.

4. Milk Paint

Milk paint is an organic preparation that gives a whitewash finish to wood.

Before paint was manufactured and sold commercially, it was made at home with simple ingredients and techniques passed down through the generations. Due to the abundance of milk in early rural America, a combination of milk paint and iron oxide (rust) or animal blood was often used to paint idyllic red barns that dot the countryside to this day, a testament to the durability of the finish.

As the name suggests, milk paint is formulated using curdled milk or curd cheese, lime, and pigment (if color is desired). I rate milk paint high on the list due to its simplicity and ease of use. It can be made with organic ingredients very inexpensively. The paint is time-tested and lovely. The only drawback to consider is that milk paint can water-spot, a likely occurrence in the garden.

After painting with milk paint, I recommend rubbing the dried surface with linseed or vegetable oil. Water spots can easily be removed with a soft cloth and oil. Some consider these spots desirable, adding to the rustic appearance that milk paint provides.

How to Make Milk Paint (Lemon Juice Recipe)

Here's a recipe to make your own milk paint with a lemon juice base.

Ingredients You'll Need

  • Mixing container with a lid (such as a wide-mouth jar)
  • Large bowl
  • Sieve
  • Cheesecloth
  • Polyester or natural bristle paint brush
  • Soft cloth or rag
  • Steel wool or sand paper
  • 1 large lemon (juiced)
  • 1 quart skim milk
  • Oil (olive, linseed, walnut, or mineral oils are recommended)

Directions

  1. In a pitcher or carafe, stir together the lemon juice and milk. Leave the mixture at room temperature overnight or over two nights. The milk will curdle. Do not jostle or stir the mixture once the lemon juice has been added.
  2. Separate the solid curds from the whey liquid by placing a sieve lined with cheesecloth over a large bowl. Pour the milk through the sieve, discarding the liquid whey or saving it for cooking purposes (it makes a wonderful substitute for water in bread recipes).
  3. If color is desired for the exterior surfaces of your garden containers, add a few drops of non-toxic acrylic paint and stir in thoroughly. Continue adding paint, one drop at a time, stirring constantly until the desired color is achieved.
  4. Use the paint immediately, as it does not store well. Apply the first coat with a brush, and allow to dry for at least one hour. The first coat may be a bit difficult to spread. After one hour, sand the paint or rub it with steel wool. Then paint your second coat.
  5. Once the paint is completely dry, rub the surface again with steel wool or sandpaper. Vacuum or wipe off any dust that accumulates, and rub the surface with oil.
  6. If the paint gets water spots, remove them by rubbing with a soft cloth and oil. Optionally, cover with a coat of SoySeal, Soapstone Wood Sealer, or a layer of homemade wood polish.