Fire from Linseed rags

[Matt B]

My son sent me a link to this video.  
A test was set up to determine if oily rags used to apply boiled linseed oil will actually self combust.  The video is 30 minutes long, but if you use boiled linseed oil, you should watch this.  Even the person performing the test was surprised with the result.  
Link to video

[dgman]

Not surprised at all! I didn’t have to see the video as I’ve known this all along. It hasn’t happened to me because I take precautions to prevent it.  I don’t use rags anymore. I use blue shop towels. I lay them on the edge of a plastic trash can till they dry, usually over night. Then they are safe to toss into the plastic trash can.

[Sycamore67]

All my finishing rags, towels, etc go outside immediately after using.   They are spread out away from the house.

[BadBob]

Nothing new. The boiled linseed oil I have tells you that on the can.

[kmmcrafts]

Not just linseed oil does this.. all oil base finishes and most chemical finishes too.. motor oil and many other things are the same way..

As Dan said I use blue shop towels.. I set mine on fire when I'm done so it's a controlled burn rather than a wait and hope it doesn't catch fire when I'm not there.. I live in the middle of nowhere so I have a burn barrel just for doing this.. once done finishing they go in the barrel and get lit while standing there. 

[BadBob]

13 minutes ago, kmmcrafts said:

I set mine on fire when I'm done

Not a bad idea. I have been hanging mine on the fence outside for years.

[Matt B]

In the video, he used paper towels and also cloth rags.  He had cameras on the trash cans nonstop.  He set up 25 different scenarios with combinations of storage containers, rags and different products.  Over a ten hour period, there were three fires.  
Up to now, I felt like I have bern aware of the risk.  Seeing how quickly these fires started, I realize that I have not been careful enough.  

[Bill WIlson]

I watched that same video a week or so ago.  I've long known about the risks of BLO rags and spontaneous combustion, but this video really highlighted just how quickly things can turn bad.  Also remember that many stains are also linseed oil based and pose the same risk.

[kmmcrafts]

25 minutes ago, Matt B said:

In the video, he used paper towels and also cloth rags.  He had cameras on the trash cans nonstop.  He set up 25 different scenarios with combinations of storage containers, rags and different products.  Over a ten hour period, there were three fires.  
Up to now, I felt like I have bern aware of the risk.  Seeing how quickly these fires started, I realize that I have not been careful enough.  

It is a great reminder for all of us,  and also we have a lot of newer members so I am glad you brought this up and as you mentioned, you knew it but didn't realize how quick it can happen etc.. This is the reason I set mine on fire and do a control burn.. even just setting them up outside to "dry" they should be watched over to be sure the wind doesn't carry them into the yard or a neighbors house etc.. I'd rather stand by a fire that I light and watch for 5 minutes than to get side tracked and forget about the rags drying out in my driveway or wherever..   

[Scrappile]

Don't forget hay stacks, they can do it also.

I also do the paper towel and hang them on the edge or the can until dry.  

Edited April 5, 2023 by Scrappile

[OCtoolguy]

5 hours ago, kmmcrafts said:

Not just linseed oil does this.. all oil base finishes and most chemical finishes too.. motor oil and many other things are the same way..

As Dan said I use blue shop towels.. I set mine on fire when I'm done so it's a controlled burn rather than a wait and hope it doesn't catch fire when I'm not there.. I live in the middle of nowhere so I have a burn barrel just for doing this.. once done finishing they go in the barrel and get lit while standing there. 

We're not allowed to burn anything. Except eletricity that is.

[heppnerguy]

I was not aware of that at all. Don't know that I have ever used boiled linseed oil yet but I am now certain I will not start using them. Thanks for posting this. I have others, like myself, that are not aware of this problem, see it too.

Dick

heppnerguy

[OCtoolguy]

I've been watching for a deal on a "rag can". Something fireproof.

 

[CharleyL]

All drying oils and many paints that include drying oils in them can do this. You need to respect the rules about safe handling of these, especially linseed oil. A significant part of my life career was that of a Fire Marshal and fire investigator. I have been to several fires that were caused by careless use of these drying oils. Don't loose your shop, garage, or house because you didn't take the time to properly dispose of rags, paper, brushes, paints, etc that were used on a project involving a drying oil. Petroleum oils are not drying oils, so are less likely to be a source of fire problem, at least not like this, but I treat them the same too. At the very least, they will burn very easily once they catch on fire. 

I have a small lidded galvanized trash can that I keep several gallons of water in. When I finish applying anything containing drying oils or boiled linseed oil, everything used to apply it goes into the water in this can and the lid goes on. Then I set it outside my shop and about 10' from anything, and it sits there for a day or two, before I remove the materials, ring them out, and put into a trash bag that gets sealed for dropping into my trash can for city trash collection. Keeping oxygen away from these oils is necessary to prevent combustion. The oxygen unites with the dryers and causes the heat, and it can build up quickly in wadded up rags, enough that they can cause a fire.

One time when I was working with boiled linseed oil on rags, I had difficulty clearing enough flat space to place the project while it dried, so the rags sat bunched up on my workbench for maybe 20-30 minutes. When I grabbed the rags to use them again they were already hot enough to give me a burn when I grabbed them. Needless to say their next position was outside the door on the driveway. I had no intention in leaving them on the workbench, but just needed a few extra minutes to better prepare the place for the project so it could dry, and those rags had already become hot enough in their center to lightly burn my hand when I picked them up to use them again. Needless to say that they got evicted from my shop quickly and I started again with new rags. Once spread out and in the open air they dried with no further problems.

At my former shop, my neighbor's chain link fence was near my shop, and I used to spread and hang my oil soaked rags on his fence to dry. If hung spread out so free air circulation can cool as well as dry your rags, like when hanging from a metal fence, they dry without problems and once fully dry you can throw them away safely. It's the drying action and uniting with oxygen without free air circulation for cooling that causes the hazard. Spreading them out on gravel or concrete will work, but it's best to get the air circulating freely on both sides. Submerging in a pail of water seems to completely cool and stop the reaction instantly.

Charley 

 

[BadBob]

Metal cans will help contain the fire if it starts but will not stop spontaneous combustion. If the can is not isolated from flammable, you could burn your house or shop anyway. The standard oily rag cans are not airtight.

Many things can spontaneously combust. Sawdust piles and hay can burn from the inside, for example. I don't think a compost heap will burn, but I have measured the temperature on mine as high as 180 degrees using a soil thermometer.

 

 

Better and cheaper to hang them outside or burn them.

[BadBob]

 

I got curious and did some digging. This is a short list of materials that will spontaneously combust. Note that I was wrong about the compost burning.

• Hay
• Straw
• Sawdust
• Coal
• Oil
• Grease
• Rags soaked in oil
• Towels soaked in oil
• Paint overspray
• Material from a paint spray booth
• Compost
• Mulch
• Manure
• Leaf piles
  
  Spontaneously combustible chemicals, such as:
• Phosphorus
• Magnesium
• Aluminum powder
• Sodium hydride
• Titanium powder
• Potassium
• Lithium
• Ethylene oxide
• Isopropyl ether
• Peroxides (such as diethyl ether peroxide and acetone peroxide)
• Some metal hydrides (such as lithium aluminum hydride and sodium borohydride)
• Some organic compounds (such as cotton, linen, wool, and some oils)

 

[BadBob]

1 hour ago, CharleyL said:

At my former shop, my neighbor's chain link fence was near my shop, and I used to spread and hang my oil soaked rags on his fence to dry.

That is my prefered method.

 

[Gene Howe]

Learned my lesson back in the 70s when I threw a batch of Watco soaked rags in a 5 gal. plastic paint bucket. It didn't totally combust but, the bucket began to melt. Garden hose to the rescue! Now, the used rags get spread out on the rocked driveway. 

[Bill WIlson]

16 hours ago, heppnerguy said:

I was not aware of that at all. Don't know that I have ever used boiled linseed oil yet but I am now certain I will not start using them. Thanks for posting this. I have others, like myself, that are not aware of this problem, see it too.

Dick

heppnerguy

You may have never used boiled linseed oil alone, but if you have used an oil based stain or varnish, wiping varnish, Danish oil, Watco oil, Tung oil etc then you have been exposed to the same danger.  

We take calculated risks all of the time.  We routinely operate power tools that employ razor sharp blades, spinning at high speeds.  We fill our lawnmowers, weed eaters, leaf blowers, etc with highly flammable gasoline.  Heck, we even store gallons of it in our sheds and garages.  Certain house hold cleaning products, if mixed together, will generate a toxic gas that can be fatal.  My point is, we use these products in relative safety, because we are well aware of the dangers.  BLO is no more dangerous than most of these products we use every day.  The most important thing is to be aware of the risks.  The steps required to mitigate those risks are simple and easy to follow.