Linseed-based dyes can be found on the shelves of every hardware store. They are used to dye furniture, floors, decking, and carpentry in your home. However, if not properly stored or disposed of, they can turn on automatically and cause a fire in your home. The vapors of wood dyes can ignite when there is a pilot light or an open flame nearby.
Fresh wood dye vapors are more likely to ignite than if the stain has been drying for a while. Well-ventilated rooms are much safer and reduce the risk of vapors from wood stains igniting when the stain dries. Wood dye is toxic during the application and drying processes, but is not toxic after a 30-day cure. Most wood dyes are not tested for food safety and therefore cannot be labeled as food-safe, but they are manufactured in accordance with FDA regulations.
Stain-resistant rags should never be left in the workplace or simply thrown in the trash. Specially constructed metal cans with spring-actuated sealing lids and double bottoms are available to be used for temporary storage and transportation of rags. If you're not careful, stained rags can ignite while you're driving home in the back of a van, or a fire can start hours later. It's good practice to have a fire extinguisher in every vehicle.
While many people recover fully from damage caused by smoke from wood inks or the ingestion of wood stains, others may experience infections, prolonged breathing difficulties, and even death. The vapors from oil-based stains require adequate air circulation and are often best dyed outdoors when possible. Ultimately, the stain is covered with another finish, and even if it wasn't, given a full cure time, the stains should be OK to come into contact with food. But water-based wood dye contains no hazardous binders than traditional oil-based wood dyes and is therefore significantly less toxic as a result.
Again, this is not a problem after the stain is dry, but when in liquid form, the wood stain is highly flammable. When you finish working with wood dye, be sure to wash the dye off your hands and clean the work area. If you used a rag to apply wood stain or to wipe off excess dye, you should leave the rag in a horizontal position to dry, otherwise it could burn spontaneously. The best way to prevent smoke damage from wood stains is to choose one that doesn't contain volatile organic chemicals.
Wood dye vapors can contain volatile organic chemicals (VOCs), such as formaldehyde, arsenic and benzene, which are hazardous and can be deadly. Vapors are dangerous because wood stains contain dyes, solvents and binders that are not safe to breathe. Last summer I was struck by the story of a fire caused by stained rags that burned spontaneously, although, unfortunately, fires caused by stained rags are not unusual. However, there are a number of edible products that can act as wood dye, if you want to use a truly food-safe wood dye.
This all sounds scary, but the risks are minimal since wood dye is used in a well-ventilated area.