Teak oil is a popular finish used on outdoor furniture and decks to enhance the wood’s natural beauty and provide protection. However, this product presents a genuine fire hazard. Teak oil is not a pure substance but a complex blend of oils and solvents, making it flammable and requiring careful handling. Understanding the specific risks associated with its chemical composition is necessary to prevent accidents and ensure safety during and after application.
Understanding Flammability and Combustibility
The risk associated with a liquid is defined by its flash point, the lowest temperature at which the liquid produces enough vapor to ignite when exposed to an ignition source. A liquid is classified as “flammable” if it has a flash point below 100°F (37.8°C). These substances produce ignitable vapors at normal working temperatures, making them highly volatile.
A liquid is considered “combustible” if its flash point is at or above 100°F (37.8°C), but below 200°F (93.3°C). This means the liquid needs to be heated above typical room temperature before it releases enough vapors to catch fire. Commercial teak oil products often contain solvents that lower the overall flash point, resulting in classifications ranging from a Class 1C Flammable Liquid (below 100°F) to a Class II Combustible Liquid (between 100°F and 140°F).
Why Teak Oil is a Fire Hazard
Commercial teak oil is a blended product whose dual composition creates two distinct fire risks. The product typically contains a high percentage of petroleum distillates, such as mineral spirits or naphtha, which act as solvents. These solvents are highly volatile and cause the liquid product to be classified as a flammable or combustible liquid and vapor.
The solvents evaporate quickly, releasing vapors that are often heavier than air and can travel along the floor to a distant ignition source, causing a flashback fire. The second risk comes from the drying oils, such as tung or linseed oil, included for the finish they provide. These drying oils are the chemical source of the spontaneous combustion risk, which is separate from the liquid’s flammability.
Preventing Spontaneous Combustion
Spontaneous combustion is a hazard unique to materials soaked with drying oils and is a serious concern with teak oil application. The process begins when the drying oil reacts chemically with oxygen in the air, known as oxidation. This oxidation reaction is exothermic, meaning it generates heat.
If the oil-soaked material, such as a rag or paper towel, is crumpled or piled, the heat generated becomes trapped. The trapped heat accelerates the reaction, causing the temperature to rise rapidly until the material reaches its ignition point and bursts into flame without an external spark. This process can occur within a few hours of use.
To prevent this hazard, all materials contaminated with teak oil must be handled immediately and correctly. The most effective method is to completely submerge all used rags, applicators, and paper towels in a water-filled, sealed metal container. The water stops the oxidation process by limiting the oxygen supply.
Alternatively, used rags can be spread out flat and unfolded in a well-ventilated outdoor area to allow the heat to dissipate safely. Once the materials are completely dry and hardened, the oxidation process is complete, and they can be disposed of in a regular trash receptacle. Never leave oil-soaked materials piled up, in a plastic bag, or in a regular trash can.
Safe Handling, Storage, and Disposal
When handling the liquid teak oil product, proper ventilation is necessary to prevent the buildup of flammable vapors. Use the product only outdoors or in a space with significant air movement to disperse the heavier-than-air solvent vapors. Keep the open container away from all potential ignition sources, including pilot lights, sparks from power tools, and open flames.
For storage, keep the original container tightly closed and in a cool, dry, well-ventilated location. The storage area must be away from direct sunlight, heat sources, and incompatible materials like oxidizing agents. Keep the container locked up and out of reach of children.
Disposing of unused liquid teak oil requires special attention because it is classified as a hazardous waste. Leftover liquid product should never be poured down a drain or released into the environment. Instead, contact a local waste management authority or a licensed hazardous waste collection point for proper disposal instructions.