I had a small can of shellac (half pint) with a press on (not screw-on)
lid, sitting on a basement shelf. Today I noticed a wet floor, though
the toilet leaked.
They saw the can on its side, the bottom buckled as if pressure built up
inside, finnally exploding the can open, and pouring itself on my floor.

WTF?? Is this 'normal'? Anything else down there ready to explode?

JOE

"JoeTaxpayer" wrote in message
...
I had a small can of shellac (half pint) with a press on (not screw-on)
lid, sitting on a basement shelf. Today I noticed a wet floor, though the
toilet leaked.
They saw the can on its side, the bottom buckled as if pressure built up
inside, finnally exploding the can open, and pouring itself on my floor.

WTF?? Is this 'normal'? Anything else down there ready to explode?


Anything else with relatively high vapor pressure that you put away cold and
allow to heat up. That's one reason for screw-on lids.

Never left a bit of cold soda in the bottom of the bottle and closed the
windows on the pickup?

Don't open it near anything you care for.

George wrote:

"JoeTaxpayer" wrote in message
...

I had a small can of shellac (half pint) with a press on (not screw-on)
lid, sitting on a basement shelf. Today I noticed a wet floor, thought the
toilet leaked.
They saw the can on its side, the bottom buckled as if pressure built up
inside, finnally exploding the can open, and pouring itself on my floor.

WTF?? Is this 'normal'? Anything else down there ready to explode?



Anything else with relatively high vapor pressure that you put away cold and
allow to heat up. That's one reason for screw-on lids.

Never left a bit of cold soda in the bottom of the bottle and closed the
windows on the pickup?

Don't open it near anything you care for.


It's been sitting there 8 years. Basement temp is stable. I avoided the
garage figuring the temp extremes would be bad for paint, solvents, etc.
Thought metal cans in basement were safe. But thanks for the reply. I'll
be more careful.
JOE

George wrote:
"JoeTaxpayer" wrote in message
...
I had a small can of shellac (half pint) with a press on (not screw-on)
lid, sitting on a basement shelf. Today I noticed a wet floor, though the
toilet leaked.
They saw the can on its side, the bottom buckled as if pressure built up
inside, finnally exploding the can open, and pouring itself on my floor.

WTF?? Is this 'normal'? Anything else down there ready to explode?


Anything else with relatively high vapor pressure that you put away cold and
allow to heat up. That's one reason for screw-on lids.

Never left a bit of cold soda in the bottom of the bottle and closed the
windows on the pickup?

Don't open it near anything you care for.

Yeah, well...I just went out to my little pick-up and found the damned
rear view mirror (with two overly heavy map lights) hanging by its
wires.

This heat is a real joy. We go years barely seeing 90, and this year, I
think we've had at least 10 days well into the 90s, most of them mid or
high. Pfui.

I'll have to drive the dangler into town, get glue, scrape and clean
and reinstall.

Charlie,

Having had to do this several times - I found out what was causing it on
mine at least. Obviously the high temp of the two dissimilar materials -
glass and metal but the main reason was that the mirror base was not flat
and even had a small, sharp bump in the casting. I did the Scary Harp
routine on it, cleaned the glass and base with alcohol then applied some
standard CA (super glue) and that mirror hasn't budged. The car is in Fla
now with my mother-in-law and its still attached. So look at the base
closely.

Bob S.


"Charlie Self" wrote in message
oups.com...

George wrote:
"JoeTaxpayer" wrote in message
...
I had a small can of shellac (half pint) with a press on (not screw-on)
lid, sitting on a basement shelf. Today I noticed a wet floor, though
the
toilet leaked.
They saw the can on its side, the bottom buckled as if pressure built
up
inside, finnally exploding the can open, and pouring itself on my
floor.

WTF?? Is this 'normal'? Anything else down there ready to explode?


Anything else with relatively high vapor pressure that you put away cold
and
allow to heat up. That's one reason for screw-on lids.

Never left a bit of cold soda in the bottom of the bottle and closed the
windows on the pickup?

Don't open it near anything you care for.

Yeah, well...I just went out to my little pick-up and found the damned
rear view mirror (with two overly heavy map lights) hanging by its
wires.

This heat is a real joy. We go years barely seeing 90, and this year, I
think we've had at least 10 days well into the 90s, most of them mid or
high. Pfui.

I'll have to drive the dangler into town, get glue, scrape and clean
and reinstall.

BobS wrote:
Charlie,

Having had to do this several times - I found out what was causing it on
mine at least. Obviously the high temp of the two dissimilar materials -
glass and metal but the main reason was that the mirror base was not flat
and even had a small, sharp bump in the casting. I did the Scary Harp
routine on it, cleaned the glass and base with alcohol then applied some
standard CA (super glue) and that mirror hasn't budged. The car is in Fla
now with my mother-in-law and its still attached. So look at the base
closely.

Bob S.


"Charlie Self" wrote in message
oups.com...

George wrote:

"JoeTaxpayer" wrote in message
...

I had a small can of shellac (half pint) with a press on (not screw-on)
lid, sitting on a basement shelf. Today I noticed a wet floor, though
the
toilet leaked.
They saw the can on its side, the bottom buckled as if pressure built
up
inside, finnally exploding the can open, and pouring itself on my
floor.

WTF?? Is this 'normal'? Anything else down there ready to explode?


Anything else with relatively high vapor pressure that you put away cold
and
allow to heat up. That's one reason for screw-on lids.

Never left a bit of cold soda in the bottom of the bottle and closed the
windows on the pickup?

Don't open it near anything you care for.

Yeah, well...I just went out to my little pick-up and found the damned
rear view mirror (with two overly heavy map lights) hanging by its
wires.

This heat is a real joy. We go years barely seeing 90, and this year, I
think we've had at least 10 days well into the 90s, most of them mid or
high. Pfui.

I'll have to drive the dangler into town, get glue, scrape and clean
and reinstall.




Back in '74 I brought a brand new Falcon. A bout 4 weeks after purchase
I took my Girl Friend (Now Wife) to the drive in. Had a mate and his
sheila in the back seat. Very proud of my new shiny red car. Set the car
up on the hump, and reached up to move the mirror out of the way so
those in the back seat could see. Yep ended up with the whole bloody
thing in my hand. Major embarrassment. Took the car back to Ford, as it
was under warranty and had the mirror re fixed. A couple of weeks later
found the mirror laying on the front seat. Took the car back to dealer,
had it fixed. A while later while driving the bloody thing fell of
again. Took the mount of, mixed some 2 part epoxy, jammed it in place
with a piece of 2 x 1 from the rear seat to windscreen until dry. That
mirror never came of again.
Regards
John

8 year old shellac is garbage....


David.

The sharp bump at the base is actually intended.
Provides a bit of stand off, such that there will be (has to be) a thickish
layer of glue. A thin layer of glue cannot handle the stress due to
expansion differences between mirror base and window as temperature swings.
A thick layer can.

Theo



"BobS" wrote in message
...
Charlie,

Having had to do this several times - I found out what was causing it on
mine at least. Obviously the high temp of the two dissimilar materials -
glass and metal but the main reason was that the mirror base was not flat
and even had a small, sharp bump in the casting. I did the Scary Harp
routine on it, cleaned the glass and base with alcohol then applied some
standard CA (super glue) and that mirror hasn't budged. The car is in Fla
now with my mother-in-law and its still attached. So look at the base
closely.

Bob S.


"Charlie Self" wrote in message
oups.com...

George wrote:
"JoeTaxpayer" wrote in message
...
I had a small can of shellac (half pint) with a press on (not screw-on)
lid, sitting on a basement shelf. Today I noticed a wet floor, though
the
toilet leaked.
They saw the can on its side, the bottom buckled as if pressure built
up
inside, finnally exploding the can open, and pouring itself on my
floor.

WTF?? Is this 'normal'? Anything else down there ready to explode?


Anything else with relatively high vapor pressure that you put away cold
and
allow to heat up. That's one reason for screw-on lids.

Never left a bit of cold soda in the bottom of the bottle and closed the
windows on the pickup?

Don't open it near anything you care for.

Yeah, well...I just went out to my little pick-up and found the damned
rear view mirror (with two overly heavy map lights) hanging by its
wires.

This heat is a real joy. We go years barely seeing 90, and this year, I
think we've had at least 10 days well into the 90s, most of them mid or
high. Pfui.

I'll have to drive the dangler into town, get glue, scrape and clean
and reinstall.

"Charlie Self" wrote in message
oups.com...

This heat is a real joy. We go years barely seeing 90, and this year, I
think we've had at least 10 days well into the 90s, most of them mid or
high.

That ain't heat...

Pfui.

A'yup!
The older I get, the less I enjoy two of the four seasons...

Theo Veenstra wrote:
The sharp bump at the base is actually intended.
Provides a bit of stand off, such that there will be (has to be) a thickish
layer of glue. A thin layer of glue cannot handle the stress due to
expansion differences between mirror base and window as temperature swings.
A thick layer can.


Mine slips into a plastic boot that I presume is supposed to handle
the expansion problem. CA glue is not supposed to be applied thick,
the design you describe was probably intended to use RTV.

--

FF

On Wed, 03 Aug 2005 13:10:08 -0400, JoeTaxpayer wrote:

I had a small can of shellac (half pint) with a press on (not screw-on)
lid, sitting on a basement shelf. Today I noticed a wet floor, though
the toilet leaked.
They saw the can on its side, the bottom buckled as if pressure built up
inside, finnally exploding the can open, and pouring itself on my floor.

WTF?? Is this 'normal'? Anything else down there ready to explode?

JOE

Anything that was colder or at lower pressure when sealed..

I learned the hard way that you don't put a new can of coffee in the RV at 300
feet and open it at 11,000 feet... we've been finding coffee grounds in the
trailer for over a year.. lol


mac

Please remove splinters before emailing

On 3 Aug 2005 13:39:39 -0700, "Charlie Self" wrote:


Yeah, well...I just went out to my little pick-up and found the damned
rear view mirror (with two overly heavy map lights) hanging by its
wires.

This heat is a real joy. We go years barely seeing 90, and this year, I
think we've had at least 10 days well into the 90s, most of them mid or
high. Pfui.

I'll have to drive the dangler into town, get glue, scrape and clean
and reinstall.

Charlie... they don't glue them any more...
I had one that I re-glued twice, with the special little kits they sell, and it
failed both times within one summer...
The new kits have a pre-cut slice of some really sticky stuff that seems to work
much better.. YMMV


mac

Please remove splinters before emailing

On Thu, 04 Aug 2005 12:58:41 GMT, "patrick conroy"
wrote:


"Charlie Self" wrote in message
roups.com...

This heat is a real joy. We go years barely seeing 90, and this year, I
think we've had at least 10 days well into the 90s, most of them mid or
high.

That ain't heat...

Pfui.

A'yup!
The older I get, the less I enjoy two of the four seasons...


I'd love to see some 90's!!!!
Last night it actually got to about 92 in the shop by 10pm...
Of course, I did have 3 BIG fans going...
I also ran a DC hose up to the peak of the ceiling and took the hose off the
bags and shoved it out a window... running it for about 20 min. brought the temp
down almost 5 degrees.. lol

The things we'll do to be able to make shavings and saw dust constantly amaze
me..


mac

Please remove splinters before emailing

mac davis wrote:
On Wed, 03 Aug 2005 13:10:08 -0400, JoeTaxpayer wrote:


I had a small can of shellac (half pint) with a press on (not screw-on)
lid, sitting on a basement shelf. Today I noticed a wet floor, though
the toilet leaked.
They saw the can on its side, the bottom buckled as if pressure built up
inside, finnally exploding the can open, and pouring itself on my floor.

WTF?? Is this 'normal'? Anything else down there ready to explode?

JOE


Anything that was colder or at lower pressure when sealed..

I learned the hard way that you don't put a new can of coffee in the RV at 300
feet and open it at 11,000 feet... we've been finding coffee grounds in the
trailer for over a year.. lol


mac

Please remove splinters before emailing

I don't mean to be dense about this but;

The can was untouched for years, 7-8 my guess. My basement is 65 in
winter, maybe 75 in summer. I should have trashed it 5 years ago.

I have gallon cans of poly, will I have the same issue?

I understand the solvent soaked rag issue, I leave those out in the yard
to dry and throw out. My real question is, was there something unstable
that caused this? And what else might blow up? No fire, but this small
can made quite the mess.

On Thu, 04 Aug 2005 00:36:07 +0000, BobS wrote:

Charlie,

Having had to do this several times - I found out what was causing it on
mine at least. Obviously the high temp of the two dissimilar materials -
glass and metal but the main reason was that the mirror base was not flat
and even had a small, sharp bump in the casting. I did the Scary Harp
routine on it, cleaned the glass and base with alcohol then applied some
standard CA (super glue) and that mirror hasn't budged. The car is in Fla
now with my mother-in-law and its still attached. So look at the base
closely.

I had a similar problem with my Beretta. I finally used some sandpaper to
rough up the glass a bit before reattaching. Worked great.

--
-Joe Wells

On Thu, 04 Aug 2005 19:19:51 -0400, JoeTaxpayer wrote:

I don't mean to be dense about this but;

The can was untouched for years, 7-8 my guess. My basement is 65 in
winter, maybe 75 in summer. I should have trashed it 5 years ago.

I have gallon cans of poly, will I have the same issue?

I understand the solvent soaked rag issue, I leave those out in the yard
to dry and throw out. My real question is, was there something unstable
that caused this? And what else might blow up? No fire, but this small
can made quite the mess.

sort of a mystery to me, also...
the rag issue needs air to happen, so unless air suddenly got in after all those
years, that wouldn't be it..


mac

Please remove splinters before emailing

JoeTaxpayer wrote:
...

The can was untouched for years, 7-8 my guess. My basement is 65 in
winter, maybe 75 in summer. I should have trashed it 5 years ago.


According to Bob Flexner's book _Understanding Wood Finishes_
shellac is acidic and shellac cans are coated to prevent
corrosion. So maybe after eight years or so the coating
broke down and the corrosion generated enough gas, hydrogen
I would think, to overpressure the can and pop it.

What is the condition of the inside of the can?

--

FF

On Thu, 04 Aug 2005 19:19:51 -0400, JoeTaxpayer
wrote:

I don't mean to be dense about this but;

The can was untouched for years, 7-8 my guess. My basement is 65 in
winter, maybe 75 in summer. I should have trashed it 5 years ago.

I have gallon cans of poly, will I have the same issue?

I understand the solvent soaked rag issue, I leave those out in the yard
to dry and throw out. My real question is, was there something unstable
that caused this? And what else might blow up? No fire, but this small
can made quite the mess.

Shellac is a natural, organic product. It is quite possible that if it
was a partial can there had been some contamination introduced at some
point that allowed bacteria to grow and eventually produce the
pressure and explosion. About the only thing I can think of.

--
"We need to make a sacrifice to the gods, find me a young virgin... oh, and bring something to kill"

Tim Douglass

http://www.DouglassClan.com

wrote:
JoeTaxpayer wrote:

...

The can was untouched for years, 7-8 my guess. My basement is 65 in
winter, maybe 75 in summer. I should have trashed it 5 years ago.



According to Bob Flexner's book _Understanding Wood Finishes_
shellac is acidic and shellac cans are coated to prevent
corrosion. So maybe after eight years or so the coating
broke down and the corrosion generated enough gas, hydrogen
I would think, to overpressure the can and pop it.

What is the condition of the inside of the can?


It didn't seem unusual on the inside, coating looked ok. Can did have
warning that it might not be good after three years but no explosion
warning.

My question remains - will Poly have the same issue? I have a new, half
used gallon can, I thought I'd keep till the next project.
JOE

Crossposted to sci.chem.coatings where maybe there is someone who
will know the answer.

Tim Douglass wrote:
On Thu, 04 Aug 2005 19:19:51 -0400, JoeTaxpayer
wrote:

...
I understand the solvent soaked rag issue, I leave those out in the yard
to dry and throw out. ...

OIL soaked rags, in particular boiled linseed oil and tung oil or
opther _drying_ oils, that is those that react with oxygen and
polimerize as a serious spontaneous combustion hazard as the
process is exothermic and the material is combustible. Solvent-
soaked rags should also not be kept indoors (for the most part,
not _used_ indoors either) both because of the danger of developing
an explosive atmosphere and for to minimise exposure.


Shellac is a natural, organic product. It is quite possible that if it
was a partial can there had been some contamination introduced at some
point that allowed bacteria to grow and eventually produce the
pressure and explosion. About the only thing I can think of.

I thought of that too, but the bacteria in question would have to
survive in a mixture with a high concentration of alcohol. There
are bacteria that do that, they can even contaminate the alcohol
used in hospitals.

Alcohol is an organic base, shellac an organic acid the reason
pre-mixed shellac has a short shelf life is that they react,
degrading the shellac. I think this is the process known as
'aponification'. Does that produce gas?

--

FF

wrote in message
oups.com...
Alcohol is an organic base, shellac an organic acid the reason
pre-mixed shellac has a short shelf life is that they react,
degrading the shellac. I think this is the process known as
'aponification'. Does that produce gas?

Saponification? As in soap-making? Not much NaOH or KOH in the can, I'll
bet.

Look up "ester."

George wrote:
wrote in message
oups.com...
Alcohol is an organic base, shellac an organic acid the reason
pre-mixed shellac has a short shelf life is that they react,
degrading the shellac. I think this is the process known as
'aponification'. Does that produce gas?

Saponification? As in soap-making?

Yes.

Not much NaOH or KOH in the can, I'll
bet.


Alcohols are characterized by an hydroxyl group:

Methanol CH3OH
Ethanol C2H5OH
etc.

Look up "ester."

--

FF