PSA ON OILY RAGS

R

rvieceli

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Feb 4, 2008
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Hey folks! Think you don’t have to worry about oily rags spontaneously combusting because you’re using low VOC low solvent finishes?

Think again!!!

[attachimg=1]

Luckily popped back into the shop after about 20 minutes to find this towel wadded up on the bench about to burst into flames. Would not have been good.

So be careful out there.

Ron
 

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That's a good heads-up reminder Ron.  [smile]  One of the reasons I prefer doing that type of finishing outside if the weather permits. I'm also a fan of the tin Surfix box, with the lid fully closed and use that a lot if I need to keep the towel moist for some reason.
 
[member=44099]Cheese[/member] working outside sounds like a great plan and I do need to do some grinding and stuff outside. But this week doesn’t seem like a good choice.  [sad]

Current heat index is 108 air temp 92. The same or hotter through Thursday.

Ron
 
The funny thing is, most people don't believe this because you can leave a rag with motor oil on it laying around forever and nothing happens. It is NOT the same thing, but this is never really explained well. It is the "drying" oils in oil based finishes that heat up like this and of course the solvents that are usually involved that accelerate it.
This can and does happen surprisingly quickly. Even stain rags, when using multiples on large jobs, need to be spread out. If they are left to hang over something that allows them to dry w/o being in a pile, they will be fine.
 
Cheese said:
That's a good heads-up reminder Ron.  [smile]  One of the reasons I prefer doing that type of finishing outside if the weather permits. I'm also a fan of the tin Surfix box, with the lid fully closed and use that a lot if I need to keep the towel moist for some reason.
Click to expand...

One well-used accessory in my shop is an unused paint can with a tightly-fitting lid in which I can put rags with chemical substances in them prior to disposal. 
 
Sparktrician said:
One well-used accessory in my shop is an unused paint can with a tightly-fitting lid in which I can put rags with chemical substances in them prior to disposal.
Click to expand...

Great idea Sparky..  [thumbs up] …I’m going to Menards tomorrow to pick up some items, I’m going to throw in a new paint can in the mix.
 
The trick I haver been using for many years now is to take the rags outside and use rocks to keep them spread out flat and secured while they dry out. Once they are fully dry, then they go into the sealed can for the next project.
 
Cheese said:
Great idea Sparky..  [thumbs up] …I’m going to Menards tomorrow to pick up some items, I’m going to throw in a new paint can in the mix.
Click to expand...
They are all plastic paint cans these days. I was just looking at one a couple of days ago at Home Depot as I wanted a metal can to use for chemicals.

I have seen pig weed mixed with the wheat crop start heating up in the grain elevator. I switched from one grain bin to an empty one running the grain over the cleaners, and the heat produced was kinda scary from something straight out of a field a day or two before. The grain elevator was eventually sold and burned down on the new owner, but he had it setup as his wood shop in one small part. He wasn't using it for grain storage, just as a work space. Not sure why it burned, but it was a tinder box. The timbers were very old and huge. It was added onto and one continuous building long before I was born. Probably made for a nice wood shop.

s-l1600.jpg
 
Also beware of CA glue. I was inside the house gluing a craft up. For wiping I was using a paper shop rag from one of those big boxes you get at Menards. All of the sudden I felt my fingers getting very warm and saw a little smoke! Read online that cotton and steel wool can cause a rapid chemical reaction generating heat when exposed to CA glue.
 
I know I ruined a perfectly good Tshirt with that stuff once.  I spilled some down the front and a spot about the size of a quarter soaked in. As soon as it hardened, the cotton became very brittle, it cracked, then those hard/sharp edges started scratching me. Out it went.
 
CRC Quick Dry contact cleaner......

90 minutes after reading this thread I was in the basement servicing my 20 year old Honeywell electrostatic air cleaner that's been pretty gritchy and cutting out a lot.  Tons of smoke and really bad air where I live from the CA wild fires, wanted it to work better.  Usually cleaning the electrostatic cells brings it around.

Well, after cleaning the cells as an afterthought I applied the CRC to the internal spring loaded contacts for cells (400 VDC) but was in a hurry and didn't let it evaporate long enough.  Reassembled, hit the switch and "POOF" two small instant fires in the contact areas as the high voltage hit the volatile, flammable cleaner.  Luckily I was near my electronics bench and had an easy clean up type fire extinguisher handy.  The high voltage power supply is now toasted but I was leaning towards replacing the unit anyhow, so the CRC fiasco made decision for me.

Takeaway:
Being sloppy, late in day and messing with a semi familiar item.  I know just enough about this device to feel comfortable but not enough to be respectful - Bad Combo!

 
jonnyrocket said:
The trick I haver been using for many years now is to take the rags outside and use rocks to keep them spread out flat and secured while they dry out. Once they are fully dry, then they go into the sealed can for the next project.
Click to expand...
  My go-to as well for stain and finish loaded towels or rags. Dry them flat outside.  I've seen way too many shop fire pictures of woodworkers who didn't know how fast the heat and combustion could occur when working with oils, stains etc.
It's very sad to see someone's dream shop or way- of- living shop burn down to the ground.
 
I've always soaked my rags in a bucket of water and then into the trash.  I never really thought this through.  The theory is that the water will evaporate slower than the solvents and by the time the water is gone the solvents are long gone. But I never end up with more than one or two rags in the trash at any time.  So I might not be a good source of information.
 
A good heads-up and interesting experiment from Bourbon Moth. Just in case anyone has doubts about linseed oil and spontaneous combustion.

 
Any solvent saturated rags I have, I rinse in water and then drape over the side of the trash to dry.

The rag will not combust while wet, and the solvent will evaporate well before the water. 

After all the solvent and water has evaporated, I toss the rag in the trash. 

I don’t remember where I learned this, but I’ve been doing it for years. 

If the rationale is defective, someone please let me know.
 
Solvent only acts as the carrier and fuel.  It's the chemical reaction of what it was carrying that is exothermic and causes heat build up.  With the solvent evaporated, it can still catalyze and build heat.  Probably faster since evaporating solvent carries some heat away.  The beautiful spontaneous combustion is when the temperature hits the flash point of the solvent. 

Now where you toss that solvent-free rag determines whether you have enough fuel to sustain combustion and it's flashpoint.  A bin of hamster bedding is probably not the best place to toss it.

:)
 
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