Usage of Tung Oil in Lacquer Paint
- Nacipe
- Aug 10
- 3 min read
In the world of traditional Vietnamese lacquerware, Tung Oil (known locally as dầu chẩu) plays an essential role. It contributes significantly to the quality of lacquer films—providing adhesion, gloss, elasticity, and depth of color. However, the handling and processing of tung oil remain a technical challenge, especially in the absence of standardized guidelines. This article explores what tung oil is, how it’s traditionally processed, the limitations involved, and how it can be improved without compromising the authenticity of Vietnamese lacquer craftsmanship.

1. What is Tung Oil?
Tung Oil is a natural plant-based oil derived from the seeds of the Tung tree. It is rich in unsaturated fatty acids, especially eleostearic acid, which contains multiple double bonds and hydroxyl (–OH) groups. These reactive sites make tung oil capable of polymerizing—that is, forming three-dimensional crosslinked molecular structures that result in a durable lacquer film.
However, this chemical nature also makes tung oil unstable and sensitive to environmental conditions, requiring careful handling during preparation and use.
2. Traditional Processing and Its Drawbacks
In traditional lacquer-making, Tung Oil is gently heated until it reaches a thick, viscous consistency. Craftsmen assess the viscosity using a traditional method: placing a drop of hot oil onto a knife, letting it cool, then stretching it between two fingers. If the oil pulls into a thread roughly the length of a sewing needle, it’s called "1-needle"; longer threads correspond to higher viscosity levels (2-needle, 3-needle, etc.).
However, this method is highly subjective and temperature-dependent, making it unreliable for quality consistency. Another method involves "trial brushing"—applying the heated oil onto a bamboo strip and waiting for it to dry to evaluate its strength and elasticity.
3. Factors That Limit Oil Quality
During the polymerization process, Tung Oil can create three-dimensional spatial bonds, helping to increase the durability of the paint film. However, this reaction also produces OH groups and free acids, which negatively affect the long-term stability of the coating. On the other hand, the complete bonding rate is only about 80%, the rest is easily affected by UV rays, air and humidity, causing aging phenomena such as peeling, fading, cracking.
Another problem is that Tung Oil slows down the drying process of lacquer. Some painters also add raw tung oil to increase freshness, but this makes the paint film less durable and more susceptible to weather effects.
4. Irreplaceable Tung Oil in Lacquer, But Can Be Improved
Recent studies have shown that Tung Oil is the most vulnerable ingredient to climate. Yet, it remains indispensable due to its crucial role in creating adhesion, clarity, gloss, and color depth. Reducing tung oil content by just 10% has been shown to significantly weaken the film’s integrity, leading to faster peeling and surface damage. Moreover, Tung Oil serves as the binding agent between the natural lacquer resin and pigment. Attempts to remove or replace Tung Oil completely result in poor performance and inferior finish.
In industry, tung oil-based synthetic lacquers (e.g., tung oil + colophony blends) that exclude Vietnamese lacquer resin has been developed. These formulations offer good weather resistance but require highly technical processing—such as heating in an inert gas atmosphere at 300°C under vacuum or steam agitation—which is incompatible with traditional lacquer-making.
5. Sustainable Direction
The current feasible solution is to improve the technique of processing Tung Oil in a more scientific direction without breaking the traditional method. It is necessary to study more carefully the temperature, time, cooking equipment, and how to check the output quality quantitatively.
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