It is important to remember that there are many products sold to the general public that are hazardous. Some people do not realize just how dangerous some of the products sold at the local hardware or department store can be, especially when the manufacturer’s instructions are not followed.
In a previous post, we discussed the analysis of debris from spontaneous combustion dryer fires. One other common spontaneous combustion scenario we see involves the use of wood stains, such as those used to finish furniture, doors, and cabinetry. These stains commonly contain an ignitable liquid, such as a medium petroleum distillate (mineral spirits) as well as a drying oil, which is typically linseed oil. The mineral spirits solvent component can certainly ignite when exposed to an ignition source, but it does not self-heat. It is the linseed oil component that is responsible for causing the spontaneous combustion to occur.
Linseed oil is the “gold standard” for spontaneous combustion—the oil is so reactive to air that, under the right conditions, rags containing linseed oil materials will self-heat and ignite at room temperature. These fires typically involve someone tossing used rags into a pile or dumping them into the trash. When the rags are packed together, the rags are insulated and the heat generated doesn’t dissipate. As a result, ignition of the rags can occur.
The laboratory analytical process for investigating a wood stain (linseed oil) related fire is similar to that of dryer fires. The debris is analyzed for traces of ignitable liquids, which would include residual solvents from the stains or other painting and finishing products. The debris, such as a portion of the burned rags, is also analyzed for residual polyunsaturated fatty acids, which are the primary component of linseed oil. It is these polyunsaturated fatty acids that are directly responsible for the product’s self-heating properties, which cause spontaneous combustion to occur.
When working with linseed oil-based stains and similar products, it is extremely important to read the product label and follow the manufacturer’s instructions for proper disposal. Most manufacturers recommend placing the used rags in a can and then filling the container with water to prevent exposure to air. Spontaneous ignition fire loss has occurred on many occasions during the last steps of new house construction due to improper disposal of the staining and wiping rags.
Armstrong Forensic Laboratory has decades of expertise in the analysis of spontaneous combustion fires, and we are happy to assist with any fire investigation. However, we would certainly prefer for consumers to carefully read labels and stay safe. Taking a moment to understand the hazards associated with a consumer product can save a home, a business, or even a life.