Fire inspectors have determined what sparked a three-alarm fire that caused serious damage to a West End apartment on Sunday.

Vancouver Fire Rescue Services (VFRS) announced today (June 4) that investigators determined that a fire in a 15th floor suite at 1275 Pacific Street on June 2 was caused by rags soaked with linseed oil that were not stored properly.

Linseed oil (also known as flaxseed oil or flax oil) and its derivatives, often used for staining furniture, can self-heat during oxidation, which can be accelerated by confinement (such as balling up or piling up rags) and can lead to combustion.  

According to CBC News, the rags in the Pacific Surf Apartments suite had been placed on top of cardboard, which in turn was on wood decking while facing the sun on a hot day.

VFRS recommends rags with linseed oil be stored in metal or soaked in water.

No one was injured in the fire.

As the building is made of concrete and due to the fast response of firefighters, the blaze was contained. However, smoke damage was visible on the exterior of the building.