Tung oil, or what is known as Chinese wood oil, is an oil extracted from the seeds of the Tung tree, which grows in China and East Asian countries, and it can also be called Japanese wood oil or wood oil. The Tung tree originated in southern China and was cultivated for Tung oil. The date of cultivation is unknown. But thousands of years ago, during the Chinese Song Dynasty, it was used for waterproofing on ships.
It is a pungent drying oil with a pale yellow colour, it’s very similar to linseed oil, soybean oil, safflower and poppy oil and is known to have a slightly golden color and is considered one of the strongest drying agents. Extremely resistant to acids and alkalis. It is used in quick-drying varnishes and paints, acts as a waterproofing agent, so it is used to seal underwater surfaces, such as swimming pools, dams, bridge and boat supports, and is used in the manufacture of tarpaulin, oilcloth, and insulating compounds. It is used in printing ink. Tung oil-based varnish helps insulate wires and metal surfaces. Tung oil is also used to make paper and fabric waterproof and as a polisher for wood. Because of its high cost, it is replaced by other synthetic oils or resins.
Tung oil is made from the kernels of the seeds of the Tung tree (Aluretis forde and Aluretis montana, Euphorbia family). The dried and pressed tang tree seeds yield about twenty percent of the oil. Under the right conditions, an acre of Tung trees will yield about two tons of Tung kernels and produce about 100 gallons of raw Tung oil annually.
Ingredients: It consists a group of fatty acids, Alpha Elosteric Acid 82%, Linoleic Acid 8.5%, Palmitic Acid 5.5%, Oleic Acid 4.0%, and the main component is a fatty acid with a chain of 18 linked carbon atoms or methylene units containing three bonds. double conjugated. They are particularly sensitive to spontaneous oxidation, which encourages cross-linking of neighboring chains.
Types of Tung Oil
Pure Tung Oil:
It is the purest type of Tung oil and is considered free of additives
Formby’s Tung oil:
Or what is now known as Brand “Minwax Tung oil”, which is not pure tung oil, where varnish is added to make it dry quickly
Polymerized Tung Oil:
Tung oil is heated to obtain it, and this makes it more durable than oil before heating
Dark Tung Oil:
It is pure Tung oil with added color
How to identify pure Tung oil
It is easy to identify pure Tung oil because it does not contain solvents. This is a good thing, as your exposure to VOCs is reduced, but it is a difficult and time-consuming process. You will have to wait at least two to three days for each layer to harden. And it takes five to seven layers to get a protective layer. Speeding up the process or applying a layer that is too thick will create wrinkles that need to be sanded. The density of pure Tung is 0.937 g/ml at normal room temperature, and it appears transparent in a liquid state.
Since Tung oil has become so popular as an environmentally friendly wood finish product, some products labeled “Tung oil” are actually blends that contain oils, varnishes, solvents, or other chemical driers, and may not contain tung oil in their ingredients. launch. It may be tung oil or it may be polymerized linseed oil. It is usually written on the product packaging clearly whether it is pure tung oil.
Tung oil uses
There are many reasons why craftsmen might use tung oil to finish and finish wood furniture. Because its ingredients are natural, non-toxic, and environmentally friendly, it does not turn yellow over time like some common finishing and decorative paints such as linseed oil, nitrocellulose paint, or varnish
1. Tung oil finish “Wood finishing”
Tung oil is very popular today among furniture makers and woodworkers because of two properties:
First, it is a naturally derived substance.
Second: After it has been used and dried on the roof (5-30 days, depending on the weather), the result is a very hard and easy-to-repair coating, so it is used on boat decks and now on floors. The oil is often diluted with hydrocarbon thinner so that its viscosity is very low and the oil is able to reach the pores and openings of the wood. This diluent evaporates within 15 to 20 minutes. Tung oil resists water better than any other pure oil and does not darken over time. It’s said to be less susceptible to mold than linseed oil.
Heating the oil to about 500°F (260°C) in an oxygen-free environment will increase product viscosity, quality, and ease of layering. Most polymerized Tung oils are sold mixed with mild industrial solvents for easier handling. Limonene is one of the least toxic solvents.
2. Oil paper umbrella
The oil paper umbrella is the traditional umbrella used in China and Japan, and it has been used by Western countries. Tung oil is the “oil” mentioned in an oil paper umbrella, which is used to protect the paper from getting wet, and to make the umbrella waterproof.
3. Tung oil products are used for packaging of food,
beverage and medicine packages. and brake linings.
According to the US Food and Drug Administration FDA, Tung oil is food safe, so the food can be placed directly on a wooden table greased with Tung oil.
4. Some other uses: Tung oil can be used as raw materials for paint and ink. Mainly used as waterproof, anti-corrosion, and anti-rust coating in buildings, machinery, weapons, vehicles, ships, fishing gear, and electrical appliances; It can also be used to make cloth, paper, soap, pesticide, etc.
How to use and apply
Apply pure Tung oil using a brush or cotton lint-free cloth. For ease of application, dilute the first one or two coats with up to 50% of an organic solvent such as turpentine. Allow the oil to soak for 20 to 30 minutes and then wipe off the excess oil with a clean, lint-free cloth. Leave it to dry for 24 hours between every second coat. Apply more layers of pure Tung oil as above, in each new layer dilute the amount of solvent used. Leave it again for 24 hours to dry.
Apply the last one or two layers of pure undiluted Tung oil without any solvents, as you did in previous applications. After applying the final coat and removing the oil residue, leave it for 24 hours and wipe it again to help dry and remove any oil that may have surfaced. At least four layers are recommended.
More layers will be required for wood with more pores and for exterior surfaces. For best results, gently rub with thin steel wool (Grade 0000) between layers. Leave it for a few days before using to allow the clear Tung oil to dry completely. Finally, and for an enhanced shine use Wax Polish Black Bison.
To adhere to the surface and provide a good base for thick coats of gloss. The thickly polymerized oil is then applied as a single layer, and allowed to dry completely.
Tung oil vs linseed oil:
Tung oil and linseed oil are among the most commonly used oils in woodworking
Each of these oils has advantages and disadvantages, and there are several differences between the two types, including:
Boiled linseed oil dries quickly, as it needs hours to dry, while Tung oil needs days to dry
Tung oil has excellent water resistance and is better than linseed oil in water resistance
In terms of color change, Tung oil maintains its color for a long time and needs to be re-covered sometimes after a while, unlike linseed oil, which loses its color with the passage of time.
As for the price, it depends on the brand, but on average, Tung oil is about 15% to 25% more expensive than linseed oil.
Teak oil vs Tung oil
The two types are easy to apply on the surface of the wood
However, Teak oil is not suitable for all types of wood and can affect the adhesion of wood to each other and change the color of some types of wood. These defects are not present in Tung oil.