9 Jan
2006
9 Jan
'06
7:16 p.m.
On Jan 9 2006, 13:05, James Fogg wrote:
Something in powdered detergents would
"sandblast" the previously
shiny
surface of the soft plastic handles of our Revereware
pots. Liquid
detergents don't cause this problem.
I don't think it's silicon dioxide, though. I've often seen the effect
you describe; it seems to happen when the wash cycle is hot and I think
it's mainly the harshness of the detergent.
--
Pete Peter Turnbull
Network Manager
University of York
9 Jan
9 Jan
11:20 p.m.
Pete Turnbull wrote:
I'd also think it was done chemicaly. I tried cleaning an aluminum pan,
that I thought was steel with lye. It bubbled a lot, and came out with
a sandblasted texture.
Normally, I wouldn't mistake aluminum for steel, but this was a well
used restaurant pizza pan that had a thick build up of carbonized
oil/grease on it, so it felt heavy enough to be steel!
Chad Fernandez
Michigan, USA
surface of the
soft plastic handles of our Revereware pots. Liquid
detergents don't cause this problem.
I don't think it's silicon dioxide, though. I've often seen the effect
you describe; it seems to happen when the wash cycle is hot and I think
it's mainly the harshness of the detergent. 
10 Jan
10 Jan
12:33 a.m.
On 1/9/2006 at 11:20 PM C Fernandez wrote:
Normally, I wouldn't mistake aluminum for steel,
but this was a well
used restaurant pizza pan that had a thick build up of carbonized
oil/grease on it, so it felt heavy enough to be steel!
Just what I wrote earlier. Aluminum, zinc and magnesium all react with hot
water to form a hydroxide, liberating hydrogen as a reaction product.
The reason your aluminum pots don't dissolve when you boil water in them is
because aluminum (and zinc and magnesium) form a thin, very tough layer of
oxide which seals the metal suface from the action of the water.
One of the classic freshman chemistry demonstrations is (or was) to immerse
a piece of aluminum under a pool of mercury, with hot water poured on top.
The aluminum has its layer of oxide removed with a bit of sandpaper and
when the metal is raised out of the mercury into contact with the hot
water, it reacts with the water, producing bubbles of hydrogen gas. This
is also why one doesn't put out a magnesium fire with water, by the way.
When a moderately strong base (such as sodium phosphate or sodium
carbonate) is hydrolized in hot water, the basic solution attacks the
oxide on the surface of the metal, forming a soluble salt, exposing the
underlying metal to the action of the water. If the base is very strong,
such as lye, the water needn't even be hot; which is how good old Drano
works (nothing more than lye and aluminum granules); the reaction produces
enough heat, which coupled with the action of the now-hot lye acts on
grease and protein to clear blockages.
All of which goes to saying why you shouldn't put aluminum, magnesium or
zinc (including galvanized hardware) in your dishwasher with dishwashing
detergent.
Cheers,
Chuck
1:22 a.m.
Chuck Guzis wrote:
One of the classic freshman chemistry demonstrations
is (or was) to immerse
a piece of aluminum under a pool of mercury, with hot water poured on top.
Our local city high school was closed for about 3 days while a Hazmat
team cleaned up a dropped vile of mercury. Some kid found it and
brought it to school, then dropped it by accident! I'm not sure if that
was a massive over reaction, or not. Is mercury really that much of a
hazzard?
All of which goes to saying why you shouldn't put
aluminum, magnesium or
zinc (including galvanized hardware) in your dishwasher with dishwashing
detergent.
That is consistent with my results with computer hardware. My pans are
iron, so they don't really get washed in the traditional sense.
Chad Fernandez
Michigan, USA
1:27 a.m.
Our local city high school was closed for about 3 days
while a Hazmat
team cleaned up a dropped [vial] of mercury. Some kid found it and
brought it to school, then dropped it by accident! I'm not sure if
that was a massive over reaction, or not. Is mercury really that
much of a hazzard?
I'd say it was a severe overreaction, as far as the actual hazard from
the mercury itself goes - not that I'm any hazmat specialist, but given
the historical damage from mercury and the amount of mercury it took to
produce it, I have trouble getting too concerned over one small vial of
the stuff.
I note you signed as being in the USA, though, so it probably was not
an overreaction as far as the legal hazard of responding with anything
milder goes, unfortunately.
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2:58 a.m.
On 1/10/2006 at 1:22 AM C Fernandez wrote:
\
Our local city high school was closed for about 3 days while a Hazmat
team cleaned up a dropped vile of mercury.
Some kid found it and brought it to school, then dropped it by accident!
I'm not
sure if that
was a massive over reaction, or not. Is mercury really
that much of a
hazzard?
I don't know--it's not the metallic mercury that's terribly reactive, but
vapors aren't awfully safe. There are safe ways to clean up the metallic
mercury--binding to a more active metal is one. Still, it's worthwhile
considering that calomel (mercurous chloride) was used since the 1600's as
as a purgative and treatment for yellow fever in humans. Mercuric chloride
(or corrisive sublimate) was long used as an antiseptic. Before arsenic
was used as a treatment for syphilis, mercury was used.
Mercury salts were extensively used as fungicides and insecticides.
And of course, you're familiar with mercury switches and thermometers, in
addition to the use of mercury in lighting devices, such as mercury-vapor
lamps and fluorescent lamps. Old photographic tintypes and daguerrotypes
were developed by fuming with mercury.
In some ways, I think we're trying to be too safe. Certainly, too much
mercury will rot your brain; witness the old saying "Mad as a hatter" from
the practice of preparing rabbit skins using mercurous nitrate for
toughening and removal of the hairs (called carroting) in order to turn
them into felt. Many workers were poisoned by the mercury. But in
general, we've always had mercury in one form or another all around us and
I've never heard of anyone dying from ingesting the mercury in an old-style
fever thermometer
The same goes for lead. In addition to the applications of lead-based
solder in electronics, the same has been used for a couple of centuries to
construct brass musical instruments. The water main that fed my parents'
house was made of lead (that use dates back to the Romans, whence comes our
word "plumber"). Lead paints were used as durable coatings for everything
from battleships to bridges Sometimes I wonder if
tomorrow's lead will be
today's mercury--that is, schools will be closed for
three days because
some child brought in a fishing sinker to show and tell..
Maybe I'm too old to deliver a modern opinion on how much exposure is safe.
Heck, I still miss carbon tet and zinc chromate.
Cheers,
Chuck
4:17 a.m.
Maybe I'm too old to deliver a modern opinion on
how much exposure
is safe.
Heck, I still miss carbon tet and zinc chromate.
Cheers,
Chuck
Well said, Chuck.
I still have a pint or so of carbon tet left and maybe two or three
gallons of seakrome.( it's getting more solid each year that passes)
Every now and then my wife spots the seakrome and tells me I should
get rid of it - "You'll poison someone if you paint anything with that
stuff". I just smile and say quietly, "I know"<g>
Cheers
DaveB, NZ
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11 Jan
11 Jan
6:58 a.m.
On Tue, 10 Jan 2006 08:58:38 +0100, Chuck Guzis <cclist at sydex.com> wrote:
On 1/10/2006 at 1:22 AM C Fernandez wrote:
Back when I studied chemistry, mercury was considered harmful but not very
dangerous. Then, new biology research proved it to be one of the most
hazardous metals because it takse very small amounts of organic mercury
compounds to cause permanent damage. I think much of that resarch started
after the Minemoto disaster in Japan.
Later research has indicated that most of the bad effects attributed to
syphilis 100+ years ago were actually caused by the treatment. The visible
lesions improved, but the brain was harmed. The expression "mad as a
hatter" comes from the fact that mercury was used by hatters, and they had
a tendency to ende up as anything from eccentic or dimwitted to raving
lunatics.
The human body is able to get rid of a certain amount of organic mercury
without lasting damage, but apparently a number of modern pollutants are
using the same quota.
--
Using M2, Opera's revolutionary e-mail client: http://www.opera.com/m2/
\
Our local city high school was closed for about 3 days while a Hazmat
team cleaned up a dropped vile of mercury.
Some kid found it and brought it to school, then dropped it by accident!
I'm
not sure if that
was a massive over reaction, or not. Is mercury
really that much of a
hazzard?
I don't know--it's not the metallic mercury that's terribly reactive, but
vapors aren't awfully safe. There are safe ways to clean up the metallic
mercury--binding to a more active metal is one. Still, it's worthwhile
considering that calomel (mercurous chloride) was used since the 1600's
as
as a purgative and treatment for yellow fever in humans. Mercuric
chloride
(or corrisive sublimate) was long used as an antiseptic. Before arsenic
was used as a treatment for syphilis, mercury was used.
13 Jan
13 Jan
2:48 a.m.
On 1/11/2006 at 12:58 PM Bj??rn Vermo wrote:
Back when I studied chemistry, mercury was considered
harmful but not very
dangerous. Then, new biology research proved it to be one of the most
hazardous metals because it takse very small amounts of organic mercury
compounds to cause permanent damage. I think much of that resarch started
after the Minemoto disaster in Japan.
Organic mercury I could believe. There was a story awhile back about a
Dartmouth chemistry professor who managed to spill a few drops of dimethyl
mercury on her latex gloves with tragic results:
http://en.wikipedia.org/wiki/Karen_Wetterhahn
I think you mean "Minamata Bay Disease" which was a tragic episode that
involved methylmercury in fish eaten by residents. There was also an Iraq
episode back in the 1970's that involved grain treated with methyl mercury
as a fungicide.
From everything I've read, inorganic mercury as
well as the elemental
metal are far less dangerous.
Cheers,
Chuck
8:38 a.m.
C Fernandez wrote:
Chuck Guzis wrote:
I guess I don't understand. I thought mercury was mercury.
Chemically, a metal behaves very differently when in a compound. Sodium
metal has a tendency to react violently with water. A chunk will fizz
violently. Ground sodium in cold water will explode, due to the higher
surface area. However, if you compound it with chlorine, you get
ordinary table salt, necessary for life.
Peace... Sridhar
From
everything I've read, inorganic mercury as well as the elemental
metal are far less dangerous.
Cheers,
Chuck
12:01 p.m.
Sridhar Ayengar wrote:
Ok, I get it. I was thinking of it as a pure substance, rather than in
a compound.
Chad Fernandez
Michigan, USA
I guess I
don't understand. I thought mercury was mercury.
Chemically, a metal behaves very differently when in a compound. Sodium
metal has a tendency to react violently with water. A chunk will fizz
violently. Ground sodium in cold water will explode, due to the higher
surface area. However, if you compound it with chlorine, you get
ordinary table salt, necessary for life.
Peace... Sridhar
12:18 p.m.
C Fernandez wrote:
Sridhar Ayengar wrote:
Ok, I get it. I was thinking of it as a pure substance, rather than in
a compound.
Yeah. I believe that the point was that many organomercuric compounds
are significantly more toxic than metallic mercury alone. The canonical
example is usually dimethylmercury. It killed a well known chemistry
professor in 1997 when she spilled just two drops on her latex glove.
Metallic mercury isn't *nearly that toxic*.
Peace... Sridhar
I guess I
don't understand. I thought mercury was mercury.
Chemically, a metal behaves very differently when in a compound.
Sodium metal has a tendency to react violently with water. A chunk
will fizz violently. Ground sodium in cold water will explode, due to
the higher surface area. However, if you compound it with chlorine,
you get ordinary table salt, necessary for life.
12:35 p.m.
Sridhar Ayengar wrote:
Yeah. I believe that the point was that many
organomercuric compounds
are significantly more toxic than metallic mercury alone. The canonical
example is usually dimethylmercury. It killed a well known chemistry
professor in 1997 when she spilled just two drops on her latex glove.
Metallic mercury isn't *nearly that toxic*.
Peace... Sridhar
Yup, read about that just last night.
Chad Fernandez
Michigan, USA
1:58 p.m.
On 1/13/2006 at 8:38 AM Sridhar Ayengar wrote:
Chemically, a metal behaves very differently when in a
compound. Sodium
metal has a tendency to react violently with water. A chunk will fizz
violently. Ground sodium in cold water will explode, due to the higher
surface area. However, if you compound it with chlorine, you get
ordinary table salt, necessary for life.
The problem with many of our hazmat regulations--particularly when it comes
to heavy metals, is that they rarely take into account the form the metal
is in. For example, if you have amalgam fillings in your teeth, you have
mercury that's been placed in your body (silver amalgam is a solution of
silver in mercury). In this form, the mercury's not particularly reactive
with the substances inside your mouth and the danger is minimal. Yet the
amount of mercury in one filling, combined with two other harmless elements
(hydrogen and carbon) to make dimethyl mercury, is sufficient o kill you
and a couple of your friends. Add a little sulfur and some sodium,
rejuggle the molecular structure and you've got thimerisal, a preservative
used in vaccines and injected right into your bloodstream.
The EU RoHS has me in a tizzy because the regulations are beginning to
mandate that lead be removed from solders used to assemble brass musical
instruments. Well, the substitutes don't flow as nicely and it's much
harder to make a strong joint. I've seen instruments that have come from
the top German manufacturers that have cold solder joints. But a musical
instrument has a very long life (50 years and longer isn't unusual); the
solder is well contained and doesn't leach from the joints during use, so
where is the harm? We're not talking about mobile phones with an average
life of less than a year here. My oldest (and still-played) tuba dates
from 1895.
Cheers,
Chuck
2:05 p.m.
Chuck Guzis wrote:
The EU RoHS has me in a tizzy because the regulations
are beginning to
mandate that lead be removed from solders used to assemble brass musical
instruments. Well, the substitutes don't flow as nicely and it's much
harder to make a strong joint. I've seen instruments that have come from
the top German manufacturers that have cold solder joints. But a musical
instrument has a very long life (50 years and longer isn't unusual); the
solder is well contained and doesn't leach from the joints during use, so
where is the harm? We're not talking about mobile phones with an average
life of less than a year here. My oldest (and still-played) tuba dates
from 1895.
Bismuth-tin solder with high-temperature soldering gear works well
enough, doesn't it?
Peace... Sridhar
2:17 p.m.
On 1/13/2006 at 2:05 PM Sridhar Ayengar wrote:
Bismuth-tin solder with high-temperature soldering gear
works well
enough, doesn't it?
Not really--"high temperature" is relative in this case. I use an
acetylene-air torch for soft-soldering; many use oxyacetylene (you're
dealing with a big hunk of metal and local heating is more improtant that
getting the entire part hot). The problem is that joints are of the
plumbing sort--you depend on capillary action to form the joint and fill
any small gaps. Eutectic Sn/Pb is ideal. The substitutes, including some
rather expensive indium alloys that I've tried, just don't flow the same
way.
I don't know of any plumber who perfers lead-free solder to the leaded
kind.
Cheers,
Chuck
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bv＠norbionics.com -
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