All You Need to Know About Wood Finishing Oils
The primary purpose of wood finishing oils is to protect and enhance the appearance of wooden surfaces. Typically used for indoor and outdoor furniture, cutting boards, cabinets and wood floors, wood oils seep into the wood grain to provide a durable and water-resistant finish.
Some common types of wood finishing include tung oil, linseed oil and danish oils, among others. These are relatively easy to apply and require minimal tools but can take longer to dry and require periodic refinishing.
What is Tung Oil
Extracted from the seeds of the tung trees, tung oil is a natural drying oil known for its versatility and distinct properties. Tung oil is highly durable, forming a hard and water-resistant barrier that protects the wood.
When boiled, the coating has a transparent and almost wet appearance or a wrinkled look when used raw. Traditionally used on decks and now on floors, this oil resists water better than other variants and doesn’t darken with age. Boiling tung oil can increase its viscosity, allowing it to seep into even the finest grain woods. But it may be less susceptible to mold than linseed oil.
Types of Tung Oil
Some commonly used tung oil variants include:
- 100% pure tung oil: This is the most traditional form of this wood finish oil, offering a deep, natural finish. It provides excellent protection but may take multiple coats and more drying time. In its purest form, this oil is non-toxic and food safe.
- Polymerized tung oil: It’s chemically treated to dry faster and produce a harder and more durable finish. This option is ideal for outdoor applications and high-traffic areas. When combined with varnish additives, it can be used as a wiping varnish, making applications easy.
- Tung oil finishes: These are premixed formulations combining tung oil with resins, drying agents or solvents. While this offers a faster drying time and more consistent finishes, this can compromise their non-toxicity and food safety.
What is Linseed Oil
Also called flaxseed oil since it’s derived from the seeds of the flax plant, linseed oil is another popular wood finishing oil. This oil has a colorless or yellow finish and can take longer to dry compared to other finishes. Linseed oil seeps into the wood grains, protecting the wood from scratches and weather changes, but may shrink upon hardening.
It’s eco-friendly, non-toxic, low maintenance and produces a satin sheen. This oil is typically used for wood products that come into contact with food, like cutting boards and wood bowls. It yellows slightly over time and is more susceptible to scratches and water rings than varnishes or lacquer.
Types of Linseed Oil
Some commonly used linseed oil variants include:
- Raw linseed oil: This is the purest and most non-toxic form and works great if applied in thin coats and given plenty of curing time. Depending on the environment and application thickness, it may take 2–10 weeks to fully dry.
- Polymerized linseed oil: It’s created by heating without oxygen, resulting in higher viscosity and faster drying time. This wood finish oil is non-toxic and contains zero VOCs (volatile organic compounds).
- Boiled linseed oils: These contain drying agents (petroleum-based or heavy metals) to make them more appropriate for wood furniture. This is the least food-safe of the three types and emits some VOCs during drying.
Know the Differences: Tung Oil vs. Linseed Oil
While both tung and linseed oils are natural wood-finishing oils, they differ in certain characteristics. This comparison highlights the properties of tung oil vs. linseed oil so you can choose which is right for your wood finishing project.
Origin and Drying Time
Tung oil or China wood oil is derived from the seeds of the tung tree, which is native to East Asian countries. It dries faster than linseed oil, often within two to three days.
Linseed oil is obtained from the seeds of the flax plant, which has multiple other uses as well. It has an extended drying time and can take several weeks to cure fully.
Finish Appearance and Color
Tung oil dries to a transparent finish but can add minimal color to lighter woods. It offers a hard, matte sheen. There might be minimal color change over time, but it preserves the original wood color.
Linseed oil dries to a softer, more flexible finish with a slight satin sheen. It might become yellowish and darken over time, especially in direct sunlight.
Food Safety and Application
Both tung and linseed oils are food-safe in their purest forms, while their variants might contain blends that might make them unsafe for wood products in contact with food. Both also need regular reapplication to maintain their protective properties.
For tung oil, multiple thin coats can allow for deeper penetration into the wood. The traditional technique involves diluting pure tung oil with solvent and using a soft, lint-free cloth to apply successions of five or more very thin films.
For linseed oil, you can apply 2–4 layers using a cloth or brush and sand between layers. Give it time to dry completely for the best results.
Durability and Cost
Tung oil is highly durable and water-resistant, making it ideal for outdoor applications. It’s also generally more expensive than linseed oil.
Linseed oil protects wood but can be prone to scratches and is less water-resistant than tung oil, making it better suited for indoor wood products. This is a more affordable option compared to other wood finishing oils.
Popular Wood Oil Features
Three key features of wood oils include mineral oil, moisture resistance and UV protection.
- Many wood oils contain mineral oils since they nourish and condition wood grains. Opt for wood oils with mineral oil to enhance the appearance of wood, protect it from cracking and warping and repel water and stains.
- Moisture resistance is a necessary feature for outdoor furniture and humid environments. Moisture-resistant oils prevent mold and mildew, minimize swelling and shrinking and significantly extend the lifespan of the wood.
- UV radiation can lead to fading, cracking and deterioration of wood. UV-protective wood oils preserve the wood’s original color, prevent sun damage and splitting and enhance the wood’s durability.