The Dangers of Floor Sanding - The Unforgettable Fire
I’m sure most of you think it’s easy, once a month you think of something to waffle on about, spoof for about for about 750 words and Robert’s a relative! Well I can tell you it isn’t and my headgear is tipped to those who have been doing it a lot longer than me. The fact is inspiration on occasion is sadly lacking and this month was one of those occasions, until that is until I looked at my favourite wood flooring forum and I saw IT.
IT was a thread entitled “After the fire” and that was what sparked (sorry) my imagination, because just like the dangers caused by airborne hazards like dust and toxic vapours, fire is a serious concern for floor sanders particularly.
The strange thing is how common the problem is without actually being seen as a problem, you see it has happened to me in a small way twice, it has happened to one a colleague in a large way once, it has happened to a friend and was nearly lethal and 5 minutes on Google will show several cases where it WAS lethal. So what are the causes?
As well as being dangerous to our lungs, wood dust is amazingly explosive, if you want to lose your eyebrows throw some on an open fire (no don’t, my conscience is already overburdened). However unlike most explosive products, when an ignition source is applied to larger amounts of dust you don’t get bigger bangs (no I’m not going there) but the far less impressive phenomena, smouldering. Now of course smouldering may not be particularly impressive but dangerous it certainly is. Loud bangs and flames are audible and visual warnings that all is not well, but smouldering is so subtle you won’t notice it until it destroys your van or worse still, burns down your clients house.
So we know that wood dust is flammable but what is the source of ignition and what physically happens?
During the course of sanding the abrasive is not only working against the wood but also the nails or anything else that may have been left on the floor or becomes unearthed during the course of the sanding. As it strikes the nail head a small spark is produced, this can happen at exactly the point that the dust particles are making their way into the mouth of the dust collection port on your sander. Should one or more of those particles be ignited by the spark it will make its way to the canvas bag of the sander and begin a process which may take several hours to become a fire.
So how do we avoid the potential for fires caused in the manner described above? The key is in recognising the hazards and eliminating them as much as possible.
First off, is the floor face nailed? If so punch the nails well below the surface.
Second is the floor greasy (like a restaurant) or is it a waxed or oiled floor, both of these massively increase the flammability of the dust. If the former you may consider cleaning the floor first if it is bad or just do what you do in case of the latter which is be aware of the risk and watch the dust bag as you sand.
Third, make sure to vacuum the floor thoroughly before sanding as small stones or other debris can create sparks just like nails do.
Fourth make sure to empty dust collection bags frequently and dispose of the contents outside of, and well away from, the building.
Finally if you do see or smell smoke coming from the dust bag or see an ever growing black/brown mark developing on the canvas it is essential to do the following. First clamp your hand around the neck of the bag closing off the point where it is tied to the machine, this stops large volumes of air getting in and cuts down the speed at which things can develop. Second, untie the bag from the machine keeping your hand clamped around the neck and third, get the bag and contents out of the building!
So, the two occasions that I witnessed a fire starting and the one occasion that it happened to a colleague the cause was as described above, the difference being I saw it happening and dealt with it, whereas the other lad had serious damage done to his van and sanders THE NEXT DAY (told you, smouldering is slow can be slow but dangerous).
The other common instance of fire caused by floor sanding contractors, involves flammable finishes and cigarettes (don’t think I need to elaborate). My friend got away with severe scorching to the room he was working in and remarkable little damage to himself, the migrant workers in Boston Massachusetts were not nearly so lucky.