HomeRoast Digest


Topic: Magnetic stainless steel (10 msgs / 269 lines)
1) From: Mike Chester
This is a multi-part message in MIME format.
This sounds like a quality pan.  The magnetic layer is added so that it =
will work with an induction burner.  Since an induction burner transfers =
energy directly to the pan via electromagnetic waves, the pan must have =
at least a layer of magnetic material to heat up.  The heat is actually =
generated in the pan, not the element.  If there is not a magnetic piece =
within the field, no heat is generated.  You can lay your hand on an =
induction element that is on and feel nothing. 
If you are asking if this would be good for coffee roasting, I would =
think that the heavy bottom and copper layer may hold the heat too =
stable.  I have not roasted coffee in a frying pan, but would think that =
you would want one that would change heat quickly in response to burner =
settings.  This type of pan would tend to hold a steady temperature =
which is desirable for "normal cooking.  A cheaper pan may actually work =
better for this purpose since it would be more responsive.  
Mike Chester

2) From: Lynne
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On Oct 28, 2006, at 12:41 PM, Mike Chester wrote:
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Interesting. I never thought of this.
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better 
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I am aiming to actually have a pan that will hold the heat - but that's =
because I am roasting on electric. If I'm ever in a home w/a good gas 
stove (oh, would MUCH prefer it), then that's something to consider.
Lynne
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On Oct 28, 2006, at 12:41 PM, Mike Chester wrote:
Arial I would think that the heavy
bottom and copper layer may hold the heat too stable.
Interesting. I never thought of this.
ArialThis type of pan would tend
to hold a steady temperature which is desirable for "normal cooking. 
A cheaper pan may actually work better for this purpose since it would
be more responsive. 
I am aiming to actually have a pan that will hold the heat - but
that's because I am roasting on electric. If I'm ever in a home w/a
good gas stove (oh, would MUCH prefer it), then that's something to
consider.
Lynne
--Apple-Mail-3--935627335--

3) From: Dan Bollinger
This is a multi-part message in MIME format.
Magnetic SS simply has more chromium and less copper, making it not only =
magnetic, but more corrosion resistant as well.  All of the 300 series =
SS are magnetic.  SS is not a great conductor of heat.   Dan

4) From: Brian Kamnetz
Thanks to all who replied for your info.
Brian
On 10/28/06, Dan Bollinger  wrote:
<Snip>

5) From: Stephen Niezgoda
Not to be contradictory but.....
300 series stainless steel are austenitic (FCC crystal structure) and are
not magnetic in the annealed state.  They may become slightly magnetic after
coldworking (rolling, shot peening, grinding etc) due to a change in crystal
structure (martensite tranformation)
Most magnetic stainless is ferritic (BCC crystal structure) and contain less
chromium
or martensitic (Body centered tetragonal) stainless.
Sorry the materials scientist can't help from coming out sometimes.
Steve N
On 10/28/06, Dan Bollinger  wrote:
<Snip>

6) From: Jim Anderson
Interesting thread.
Although a bit off topic, this has answered a question I have had for a
while. A friend of my son's is an elevator mechanic and he gave me an old
stainless door off of a repaired unit. It is about 2' by 7' and 1.25" thick.
It is in great shape and I am using it as a work bench top. Noticed one day
that a magnetic tipped screwdriver stuck to it and didn't know why until
now.
Thanks,
Jim Anderson

7) From: raymanowen
Two things about "Stainless Streel"- It's a marketing term.
Not all such metal is chemically neutral in any given environment, nor does
magnetic permeability contraindicate "Stainless Steel."
The copper in inductive cookware forms a low resistivity shorted secondary
turn of a transformer. The primary winding is in the cooktop itself.
The cookware could be fabricated of stainless without any copper because
the S/S would act like a shorted turn secondary in the same transformer.
The- lower- heat would be generated homogeneously due to the eddy current in
the pan bottom. No copper needed for heat transfer, the heat being generated
in situ.
Aluminum or Silver would work too, especially with their lower resistivity
than stainless
I hope the bench top is not solid Stainless! At 2520 cubic inches volume, it
would weigh over 700 pounds!
Cheers -RayO, aka Opa!
-- 
"When the theme hits the bass, I dance the Jig!" - -Virgil Fox at the Mighty
Wichita (ex- NYC Paramount) WurliTzer- 1976

8) From: Dan Bollinger
This is a multi-part message in MIME format.
Thanks for the info, I was told wrong and repeated it.  I stand =
corrected.  
Did you know, when you say "Not to be contradictory but..."  that really =
means "Not to be contradictory, but I will."  It's the psychologist =
coming out in me.  ;)  
Anyway, I checked and you are right. 300 series is generally =
non-magnetic.  Dan
  Not to be contradictory but.....
  300 series stainless steel are austenitic (FCC crystal structure) and =
are not magnetic in the annealed state.  They may become slightly =
magnetic after coldworking (rolling, shot peening, grinding etc) due to =
a change in crystal structure (martensite tranformation) 
  Most magnetic stainless is ferritic (BCC crystal structure) and =
contain less chromium
  or martensitic (Body centered tetragonal) stainless.
  Sorry the materials scientist can't help from coming out sometimes. 
  Steve N
   
  On 10/28/06, Dan Bollinger  wrote:
    Magnetic SS simply has more chromium and less copper, making it not =
only magnetic, but more corrosion resistant as well.  All of the 300 =
series SS are magnetic.  SS is not a great conductor of heat.   Dan

9) From: Aaron
Ray, true on the shorted secondary for the inductive heating, BUT,  
while it will heat with any metal really as you stated, the copper does 
have a better heat transfer / heat conductivity than the stainless does, 
and aluminum for that matter, so probably works better at getting the 
heat 'up to the food' than the stainless does. Silver would work great, 
as would gold too but hmm the price, ouch.  Maybe a rich oil baron arab 
prince could afford such but I sure cant.
Oh and a motor is a rotating transformer with it's secondary shorted :-)
aaron

10) From: raymanowen
Aaron, roger on the magnetics. The thought of Gold crossed my mind, but in
deference to the Carpal Tunnel-afflicted that can't endure the pain of
stirring a pound mass of beans in a HG/DB roaster, I hit on the idea of
aluminum. A small penalty would be due to higher resistivity limiting eddy
currents, so lower IČR power/ heat generated.
Easily offset in the primary design of the inductive heating cooktop.
Sooner, rather than later, there will be superconductors that will exhibit
the property at cooking temperatures. Then there will be Hell to pay in
Peoria when someone turns on the cooktop and the pan of stew flies into the
air...
Cheers -RayO, aka Opa!
"The indisputable truth is that no coffee is fresh if it isn't fresh
roasted."- -Martin Diedrich


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