Friday, July 11, 2008

Beware of polyurethane dust

Well, it happened again... I learned why not to ignore the warning labels on chemical products! In a sort of marathon session, my wife and I finished the hardwood floors in 6 large rooms and 3 walk in closets in less than 4 days. In the process, we created a lot of dust. Dangerous dust it turns out.

After nailing down the new flooring, I sanded the floors with an orbital floor sander rented from Lowes. (my previous effort at floor finishing convinced me that I don't have the magic touch required to get good results from a commercial drum floor sander.) First, I used 36 grit, then 60 grit, then 80 grit. After the floors were reasonably smooth, we applied a coat of oil based polyurethane using a lambs-wool applicator. When the first coat had dried (about 12 hours later), we sanded the floors lightly with 220 grit sand paper and vacuumed up the residue with a 6 gallon shop-vac, followed by a thorough wiping with a tack cloth. Then we applied the second coat and repeated the same procedure before applying the third coat.

The first day we had the sander rented (I was hoping I would only need it for one day!), I stayed up until 3:00 am sanding floors. OK, I could see it might take two days, but by golly, I wanted to get my $35-per-day's worth from that machine. Three and a half days later, exhausted and covered in dust (the respirator only covers your face!), I was glad to return the sander back to Lowes. The lady at the counter (the same lady I rented the machine!) had pity on me and the four kids and only charged me for one extra day.

That weekend, I made good on a long overdue promise and took the family camping. We didn't have enough room to take all of the kids and the gear on our Polaris Ranger in one trip, so my wife volunteered to stay behind fora while until we had the campsite set up. While she was waiting on us, my wife decided to vacuum some dirt in the sunroom. When I came back to pick her up, she said "You can really smell the polyurethane dust in this shopvac." A dim synapse in my brain flickered and then fired... "Um, I remember reading on the label that the dust from buffing polyurethane can spontaneously combust. Just to be safe, I'll empty the bag." With that, I removed the disposable bag from the shop vac, threw it in a plastic trash bag and tossed it into the back yard. We went camping and never thought a thing about it. Until...

Two days later, I was mowing ironweeds in the cow pasture about a quarter of a mile from our house site. I thought I saw a puff of smoke from the house site. Was it my imagination? I strained to see if it was really smoke. It looked like smoke. I put the tractor in high gear and started booking it up the hill, hay cutter in tow. The closer I got, the more I could see that it really was smoke, and it looked like the house was on fire. I was terrified until I realized the fire was coming from the backyard. There sat glob of burning trash on fire. I put the fire out and wondered why anyone would burn a bag of trash in our back yard. It literally took at least a minute for me to realize that the bag of polyurethane dust had caught on fire by itself. The warning label had said it could, but I never imagined it would happen.

I shudder to think about what might have happened if the bag of polyurethane dust had been left in the plastic shop vac inside the house. If one good thing comes from this blog, perhaps it will be that someone will read this and remember to dispose of that polyurethane dust safely. The same goes for oily rags... they catch on fire too - I've seen it happen with linseed oil.

Less about fire, and more about flooring in my next post...


Anonymous Anonymous said...

I had a similar experience with polyurithane and a hand random orbit on a small 10x10 room. I was wondering why my fiance would be making hot-dogs, something neither of us can stand when in the back of my mind I also dimly remembered that polyurithane dust spontaneously combusts and that I was probably dealing with a collection canister that was smoldering.

Glad to hear you didn't have more serious consequences, as I was cringing from the moment I started reading that till the fire was out. much admiration on your project!

July 12, 2008 at 9:51 AM  
Blogger oldmilwaukee said...

Thanks for helping get the word out by describing your experience. The dust from a 10x10 room can just as easily start a fire as the dust from ten large rooms. After telling my story, I have been told of three different houses/cabins that burnt down just as they were finishing the hardwood floors. Unfortunately, I think the spontaneous combustion phenomenon is all too common.

On a somewhat related topic, I'm thinking that every trash can in our house is going to be metal (with a lid) when we move in. A friend of ours swears by his beat-up-looking metal trash can in his kitchen. He used to own a nightclub and said that historically, most nightclub fires have started in the trash.

July 12, 2008 at 10:17 AM  
Anonymous Anonymous said...

Here I am looking for timberfaming info for a "playset" and I come across your blog. I tip my hat to you dear sir! Great job on everything. I am sure your efforts are legendary to say the least.

July 27, 2008 at 6:44 PM  
Anonymous Anonymous said...

Believe it folks. Yesterday my non-smoker flooring guys applied the 3rd coat of poly to the floors in my new lake house. I hadn't planned on going up there until tomorrow... but this afternoon, the neighbors called to tell us the fire department had just left. Fortunately the big plastic garbage can had been left in the middle of our driveway and the flooring folks didn't move it before they(presumably)put the floor sandings in it. Burned half the landscape to nothing, but didn't hurt the house. Before four days ago, the garbage can had sat in the same spot, on the front porch, for the last 2 months! Needless to say, today would have turned out very differently if it had not. Take it seriously, polyurethane dust can and DOES spontaneously combust.

March 30, 2010 at 11:15 PM  

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