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31 responses total.

Hmm, I haven't really used one for years.  I suppose the more you spend,
usually the higher the quality.  

I think the next time I buy a Thermos-like container, it'll probably be
one of those steel ones, if only for their durability.  I've had too many
of the glass ones end up as a pile of shards after being bounced around.
Are the steel ones really more efficient than glass, though?

I use a steel Thermos. Its pretty good. One warning about it though - don't
clean out deposits from coffee or tea with chlorine bleach. I did, and it
wasn't long before the steel punctured. I now use perborate bleach - which
takes much longer, but isn't going to corrode the steel. 

 how strong was the bleach?

Oh, just a dollop in the thermos full of water. The problem is that
stainless steel is no good with chlorine - decidedly not "stainless"
(it dissolves). I didn't think it would be serious corrosion, but it
was.

 Maybe you should have made a 100:1 solution of bleach and water (100 parts
of water), and that would reduce the corrosive effect.

 Will tin rust?

"Tin" means both the element Sn, a metal moderately resistant to corrosion,
or as a general term for steel sheet plated with tin. Only iron "rusts"
(rust=iron oxide), but tin does react slowly in strong acids or alkalis. 
Tin does not protect iron like zinc does - galvanically - so iron exposed
by a pinhole in tin plate will rust as quickly as unplated iron. 

Is this why tin roofs rust eventually?

"Tin" roofs are likely not to be tin-plated, but rather galvanized. The
term "tin" is used loosely for any thin steel sheet. I just looked up
metal roofing in a building materials catalog, and it is 29 gauge
galvanized (zinc-coated) steel - no tin. It should have been "Cat on
a Hot Galvanized Roof". Galvanized steel roofs will last a lot longer
than a tin-plated steel roof, because exposed steel of a galvanized roof
does not rust until most of the zinc is gone, while it would start to
rust immediately with the smallest pinhole, if tinned.

AAAAH!  Thanks Rane!  I was wondering why the "tin"roofs on all the old barns
and stuff was only just begining to rust after around 30 years....that zinc
must be hard stuff to wear off so slowly!

It's not the strength of the zinc itself, but the way it bonds to the iron.
It is chemistry rather than materials science.

Materials science is chemistry...but we'll let that go. Zinc corrodes
slowly but also becomes coated with a protective layer of the basic
carbonate. More important, it does not engage in an electrical process of
self-destruction that involves products of rusting of iron. Then, as long
as there is zinc near iron, even after the zinc gets holes in it, another
electrical process causes the zinc to be sacrificed rather than the iron
(a process called "cathodic protection" - it is used on ships too, to
protect parts like the propeller shaft, by clamping on a "sacrificial"
disk of zinc). 

AAAhhhh! so a tin roof might not be such a bad idea for a house...

I've often seen galvanized steel roofing on houses in rural areas. Perhaps
they are used more there because they are common for farm buildings. 
_Architectural Graphic Standards_  says they should be *painted* every
3 or 4 years. (AGS refers to metal roofing in general as "Tin Roofing",
but has additional sections on copper, zinc, galvanized iron, lead,
and canvas (!) roofing.) Industrial buildings usually use corrugated
galvanized steel roofing with no underlay but the homes I've seen use
what is called "standing seam roofing", which is laid over sheathing.

I'd like to put a metal roof on the house I'm planing to build.  The 
other day I was blown away when I came across a house with a stainless
steel roof while riding back from Cycle Cellar on Felch St.  It was
of the standing seem variety and, beaing a part time machinist, I'm
pretty sure it was not aluminum.  (This house has been under construction
for several years and seems to be a DIY project.  It is quite unique
and turning out quite nice!)
 
I have run across "corrugated" galvanized roofing being used in energy
efficend designs in Sweden.
 
BTW, what are the byproducts of a stainless / chlorine reaction?

Chlorides....(iron, chromium, nickel...). However in alkaline medium these
precipitate again as hydroxides and oxides, but get washed away. Titanium
would be OK. I don't think you will find any *rural* SS roofs (except in
a high rent district).

Boy do you have that correct, Rane.  I recently checked into different roofing
materials at the 84 lumber yard.  They have "tin" roofing which is painted
and has a 30 year warranty on the paint.  Guess it is somehow bonded to the
metal.  They looked pretty cool and I have seen some on houses around the
area.  Guess I will have to do some thorough checking before any decisions
are made, but seemed like the metal roofing was almost as expensive as the
tile stuff.  What is that raised seam thing Rane?  Sorry to be so stupid on
the subject...only just starting to investigate it.

If you ever drive through Baraboo, Wisconsin, about 2/3 of all the houses have
standing seam metal roofs.  Seems there was a very successful tinsmith years
back.

The separate "tin" sheets have bent-up flanges along their sides. On some
varieties, the flang is bent up and then over and down, and the flange
of the next sheet fits under that. On others, apparently, the overlap is
small, and that is bent over in place to seal the seam (it is easier to
draw pictures of this than describe it). Standing seam roofing requires
a roof pitch of 1/4 or greater. I'm not sure of all the issues involved
in choosing one roofing over another, besides cost. I think I recall that
the steep-pitch, standing-seam tin roofing is useful in areas of heavy
snow, as the snow slides off most readily.

I suspect that tall seams helps by getting the leaky (or potentially leaky)
part up off where the water is going to sit.

A bit further north of here in MI you'll see houses where the lower
portion of the roof is covered with sheet metal.  I suspect because of
problems with ice dams.  Shingled roofs are popular here butI'd like
to try something different.  I don't like the idea of tossing 2 or 3 
cubic yards of old shingles into the landfill every 15 or so years not
to mention another $3 to 5 grand to pay for it all.

In my neighborhood there are some houses with metal roofs that have seams.
the seams are about 2 feet apart and stick out about 3-4 inches.  The seams
run verically, as you might have guessed.

The house we used to own in Ann Arbor (1110 Miner) had a metal roof,
to go with the rest of its metal exterior ... when someone was getting
estimates for having it painted, we had to remind them that the roof
also needed painting.

Aaahhh yes!  I recently purchased two sheets of galvanized, corogated (sp)
metal to put over the top of the cister.  From this experience, I can see what
you are talking about with the raised seams.  The seam area must just be a
bit higher than on these peices, but the fit of one under the other was
excellant.  (oops I mean pieces)...Boy, I can't spell today!  change to great!

Hmm... apparently the Lovelaces were just a few houses down from where I now
live.

I have a metal roof, (and a metal house, too), but it is a "Lustron", and the
roof is made to look like tiles.  Big tiles.  :)

There are several of those metal houses scattered around Ann Arbor's West
side.  I've never lived in one though.  Every few years the A^2 news
features them and interviews people who live in them.

Is it noisy in the rain? 

I was in a metal roof building in a violent hail storm and it was so loud it
was deafening.  When the storm cleared, a tornado had just passed within 500
feet and taken down many trees, ripped off the roof of the building next door,
and turned over many trailers and trucks.  The hail storm was so loud we did
not hear the tornado.

Metal roofs are not loud, at least not by the time you put in a foot of attic
insulation!  And a good quality roof is thicker metal, which doesn't sound
the same as a "tin roof".

Aaaahhh, but the sound of rain on the roof is a very easy sound to sleep to!

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