i know there will be a consensus here and it will be reached easily
i did not want to hijack the other thread on BLO so posting here
i have read in various places the BLO (boiled linseed oil) is not the most
stable finish and in fact it has a propensity to spontaneously combust
is this hogwash or legit
On Friday, August 14, 2015 at 7:34:30 PM UTC-7, Electric Comet wrote:
Both. Boiled linseed oil soaks in, then oxidizes and polymerizes
(gums up). The oxidation can be a cause of spontaneous combustion
if you leave a pile of rags saturated with the oil, because the "boiled"
variety has catalysts that make it oxidize readily.
The finish, AFTER a cure period, is stable - and easy to renew- and
lasts nearly forever. The liquid, kept sealed away from air, is stable, too.
This is generally true of any oil finish (linseed, tung,
etc). As the finish dries, it polymerizes (the oil molecules
link together), which is an exothermic reaction (generates
If the finish is spread out (i.e. is on a surface you're
coating) that's no problem, because the heat dissipates.
If it's not spread out (e.g. is soaked into a wadded up
rag) the heat is trapped, and can increase to the point of
For safety, you should spread your used rags (or anything
else coated with oil) out somewhere with good air flow,
and allow them to dry completely before throwing them in
Once dried, oil finishes are safe and stable.
i thought that the boiled variety had some special characteristics but i
do not recall what they are
perhaps the boiling causes the chains to link together in larger than
naturally occuring chains and makes the curing process proceed
further into its stable finished form
i have left mine on the bricks to dry
an article i read seemed to imply that even when dried and stable it
had increased combustability
"Boiled" linseed oil dries faster (raw linseed oil takes a
very long time to dry). Today, no-one boils oil, instead
they add a metallic catalyst which has the same effect.
I'd be dubious that wood finished with linseed oil, or
anything else for that matter, is any more combustable than
unfinished wood. Once it's ignited, tho, finished wood
will burn hotter than unfinished wood.
Any oil based product is going to have a propensity to spontaneous
combustion. But that is only until the product cures. The biggest risk
is not being careful with the used rags and or brushes. Don't toss them
in a trash can. I lay mine spread out on the concrete floor until they
are dried, and then I throw them away, "on trash pick up day".
On Saturday, August 15, 2015 at 10:56:59 AM UTC-5, Leon wrote:
That's a great way to handle it. Spontaneous combustion of rags with oil b
ased finishing materials on them is very well documented and you treatment
is pretty much the "by the book" remedy to prevent a fire.
Personally, I have never seen it happen, but I actually knew a finisher tha
t said his rags started to smolder inside a trash can he was using to toss
all his dirty rags in while at work. It took two days, but he said there w
as no doubt in his mind it was ready to flash.
The oily rags thing got pounded into me in my jr high shop classes. Growing
up, I knew of several fires caused by oily rags. It still happens from time
to time on the local news. There was a fire in town here last year from
somebody refinish their floors. The floors were fine. It was the rags
piled up in the corner that caused the fire.
I used to have a metal can to put the oily rags in. But they still got hot.
So I started to put them out to dry. But rainy weather often interfered
with that. If I have a sunny day, I will put out he rag to dry. Otherwise,
I just burn the rag. A little newspaper and it burns right up. I supervise
it till it is all gone. And I do it on concrete.
Some people just don't get this simple fact. I have had them pick up my
drying rags and throw them in the trash. If there are any folks around I
don't trust or know, I burn the rags. So folks think I am some kinda
pyromaniac. Just the opposite. I want to PREVENT fires. Not cause them.
On Monday, August 17, 2015 at 1:34:04 PM UTC-5, Lee Michaels wrote:
Same here, I leanred that in 7th grade. I never questioned it since I didn
't know ay better, but I seemed to have forgotten it along the way. Then I
didn't do any finishing for years.
And yessiree, we have fires every year behind nearly finsihed construction
projects from oily rags being incorrectly disposed of. Fires in dumpsters,
fires in trash piles, you name it.
When I am on a job that generates a lot of dirty rags full of solvents and
oils, I try to dry them out before I dispose of them. If I can't, I picked
up a tip from an older fella many years ago. He told me that in HIS day,
they had sealed metal cans that they put the rags in and dumped them out at
the shop to dry. He said the proper procedure was to put about 3 inches o
f water in the can (about 5 gallon size) and dump the rags in and put the l
id on. I have used his method since then, and have had no problems. I pou
r them out when I can and let them dry out, then toss them.
I think that is a pretty good idea myself, and have burned a few rags where
I can. It is an instant kill shot on the problem and lets you go on your
way with one less worry.
"Lee Michaels" <leemichaels*nadaspam* at comcast dot net> wrote in message
As someone else stated, BLO is no longer boiled to get an initial
polymerization. Today, metal catalysts are added. The polymerization gives
off heat. This heat can be enough to ignite a rag if it is crumpled up. If
the rag is spread out, the heat will dissipate into the surrounding air. I
just hang my BLO rags on a chain link fence and then toss them with the
regular trash the following day. Once polymerized, BLO is not going to give
off any heat to cause a fire.
Please keep in mind that an office building in Philadelphia lost several
floors to BLO contaminated rags that were thrown into a closet before they
had a chance to fully cure / polymerize. The heat generated from
polymerization was enough to ignite the balled up rags.
On Friday, August 14, 2015 at 9:34:30 PM UTC-5, Electric Comet wrote:
I'm convinced it legit, though I've never experienced it. I use to use BLO often and would take care to either burn the rags, myself, or seal them in paint cans, before tossing in the trash can. I don't "trust" any oily rags.
yes it seems BLO has been used for a long time
there's a recipe for leather preservative that uses BLO and animal fat and
i always just toss the rags or paper towels
was concerned with the finished product but it seems to stabilize
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