This item text has been erased.

44 responses total.

I have one - I bought it at a flea market. Its an antique. Its made from
several levels of metal disks with perforations. At one time you could get
an asbestos disk with a metal rim for the same purpose - until asbestos
became tres mal. Try a hardware store, for starters. 

Call Kitchen Port at Kerrytown ask if they carry it.  Also call Hertlers.
If you're not successful in Ann Arbor, would you consider asking your mom to
call Bloomingdale's Housewares Dept. in NYC.  They seem to have almost
everything.

I made one out of a chunk of 1/4 inch aluminum plate ;)

I've made them out of a wire hanger.  you get just enough air flow under the
pot to even out the temp.

This response has been erased.

Stores specializing in backpacking supplies/goods ought to have this item,
although it's apt to be on the small side.  Some backpacking stoves need them
because they don't simmer well.  I wonder also if a supply house that sells
chemistry products (flasks, burners, etc.) wouldn't have something that would
work.

r.e. #6 In my basement.  I hang onto stuff like that when I come across it.

You could use a cast-iron skillet.

I checked both REI and Campmoor catalogs before writing #1, having the same
thought as #6 - but was unsuccessful. I just checked the Fisher catalog,
and they have nothing like the old asbestos-wire squares. In fact, burners
(Bunsen, etc), with which the heat dispersers were used, have almost
disappeared from laboratories for general heating - hot plates are used
almost exclusively, and they have thick aluminum tops for heat dispersal.

Well, I bought a ridged-metal disk at the Bivouac here in AA a few
months ago, for my MSR stove that doesn't like to simmer.  As I said,
it's probably on the small side if you're thinking of rangetop use.
I can't recall if they had a larger diameter model as I was thinking
light weight at the time, but it might be worth a call to find out.
I guess I shouldn't be too surprised about the chem lab suppliers not
selling asbestos products anymore, but I remember those wire mesh ones
were quite nice.
 
The cast iron skillet idea sounds like it might be worth a try.  You
can often find such skillets at garage sales.  For that matter, a
cheap new skillet that isn't worth cooking in might be worth cooking
over...

This response has been erased.

We have a big cast iron skillet and it is great for making pancakes and such.
It even out preforms the fancy, high end, aluminum one.  We just recently
got a *huge* Lodge cast iron dutch oven for stews and such.
 
I think an aluminum or copper disk would work the best since those materials
are good heat conductors.  The thicker the better.

This response has been erased.

Congratulations! Please describe each style for us, so we can trace
the technological evoluation of heat diffusers.

This response has been erased.

I can understand the warning because you can melt, or oxidize, both copper
and aluminum, at high heat. Mine is 8 inches in diameter and consists of
two disks of steel - apparently a rust resistant alloy, although magnetic
- the lower one like a pan, crimped together around the top edge, with
three rings of holes (8, 16, and 24) in the bottom and three rings of
larger holes (12, 24, 24) in the top. It also has a bent steel wire
handle. (Say...how'd you like to come up and see my heat diffuser? B^})

This response has been erased.

Try a magnet. Aluminum is non-magnetic. Ordinary steel is magnetic, but
some stainless steels are not. If it is not magnetic, try scratching it.
Aluminum is soft, and stainless is much harder (compare to other steel
and aluminum items you have). You can put a hole in the bottom of a
dry aluminum pan in no time with a gas flame. Copper will take longer,
but you can see it turn black and flakey as it oxidizes. (Now, about
that heat diffuser assignation...........)

This response has been erased.

Yup. Please call ahead as I may have to do some deliveries.

This response has been erased.

This response has been erased.

Let me guess.  You have a gas stove.

This response has been erased.

Hummm.  Then the blackend portion must have been sitting on a hot-spot
in the heating coil, causing it to oxidize on the surface more there.
I wouldn't worry about it.

My heat diffuser is for a gas stove - the discs and holes keep the flame
from hitting the bottom of a pot directly, and also spreading out the hot
gases. I don't think it would work well on an electric stove as it would
have too much thermal resistance. I suggest, therefore, Klaus' original
idea - a thickish (ca. 1/8" +/-) aluminum plate. You could proably buy
a small aluminum griddle at the Kiwanis used-stuff store.

If you find a small metalworking shop, you could get them to cut one out of
almost anything.  I used to know a guy in Lansing who would do that sort of
stuff at a reasonable price, so there ought to be someone here like that.

This response has been erased.

Aha - steel plated with copper for sales appeal - like Revere ware, where
the copper is too thin to do much heat spreading, but a good sales gimmick.

I think any kind of spacer between the electric burner and the pot will do
the job.  It reduces the heat transfer via conduction.  Pots / etc. with
thin bottoms are a problem because the heat doesn't have a chance to spread
out before it hits whatever your tyring to cook / heat.  
 
Rane brings up an issue my wife and I constantly complain about.  We cook
much of our food from scratch.  our family of 4 goes through about 50 lbs.
of flour a month, just to give you an idea.  Too many of the appliances and
utensiles are designed first for looks and second for function.  Our $700
Coloric stove is a piece of junk.  It's difficult to clean, uses a lot of
electrical energy, despite being gas, and the burners on top are poorly
designed and don't heat well.  Looking around, we see that a decent stove
will set us back about $2000 or more.  Even many of these are not well
designed.  Another thing that bugs me is that you can't test them.  Buying
an appliance is like buying a car without test driving it.  You only find
out how well it works after you've payed for it and hook it up.  I guess 
that, once again, shows the priorities for the avrerage consume:  Looks
first functionality second?
 
If your wire gizz works, popcorn, keep using it.  You won't harm anything
doing so.
 
(Could someone tell me why "convection ovens", all the rage these days,
have electric fans in them?  Also, why does a gas stove come with an
electric convection oven?  Oh, and why is being able to simmer on a gas
range a $150 option on many models?)

I bought a stove once because the dials had lights that changed from blue
(low) to red (high) as you turned them. Really neat! Oh, it cooked OK, too.

This response has been erased.

I have a Jenn-Air that works pretty well.  It has down-draft ventilation
which I *really* like, solid disk elements which heat evenly (but take
a while getting hot), and a convention oven which gives you the option
of having the heat blown around the food which tends to give things
a seared or crisp outside, moist inside, and generally takes less time
to cook.  It only matters when food is uncovered, natch.  And I know
it's probably a huge waste of electricity but I'd never ever again
own an oven that wasn't self-cleaning.

The griddle component is nice for big batches of griddle-type
food.  But I found the grill to be mostly useless.  It doesn't
get hot enough to be useful for true grilling.

What Mary says make good (engineering) sense. Circulating the hot
air increases the *heat transfer coefficient* between the air and
food, which increases the surface temperature - hence the seared 
outside. It also increases the *mass transfer coefficient*, which
tends to dry the outside, hence the greater crisp.

This response has been erased.

We used to have a Jenn-air.  The vent is in the middle of the stove, sucking
*down* and out thru a hose in the bottom.  We could even rotisserie, although
we had added a bit of sheet metal to keep the heat in.

That thing was a *bitch* to clean properly.

I've seen the Jenn-air ranges and always wondered about the center vent.
It seems to me that it would need a bigger fan to draw the heated air
*down*, against it's natural tendency to go up.  I can also imagine it 
being difficult to clean since it's in the middle of the range, between
the burners.
 
Putting a fan inside an oven does make sense when it comes to circulating
the hot air.  It's the word "convection" that throws me.  Convection is
the process of warmer fluid rising and a cooler one sinking.  Putting a
fan in there is anything but convection!  Matter of fack, the "old" style
ovens without fans were convection and what they are calling convection
ovens now are really forced air.  Oh well.  More english language abbuse ;)
 
I have a theory on the simmer option but non for the elusive gas oven.

You are thinking of what is called "natural convection", Klaus. The other
type is "forced convection". Natural convection over short distances is
very weak, and easily overpowered by very little fan power. Over large
distances, however, as in thunder clouds (!), it can become very powerful.
Anyway, "convection" is the general term - except among civil engineers,
where the term "advection" is more common, because originally all of the
flows they considered were horizontal. 

I suppose.  Forced convection is not what the mind conjers up when looking
up the word "convection" in the dictionary... At least not my mind ;)
 
The new burners on gas ranges go from off to High and then on down to low.
They use to go from off to low and then on to high heat.  With the old
style it was possible to go between low and off to get the simmer you wanted.

The problem was that it was possible to set it so low that the flame would
go out and than the weeping gas would fill your house and the whole mess
would blow up when it found a spark or flame.  Liability being what it is,
the burner controls were changed so you could only go so-low and always
have a flame.  The problem was that to simmer your stew, you had to set the
pot up on some bricks so the low flame wouldn't give your stew that burnt
tast.
 
Hence the gas stove simmer option was invented!  This option lights your
burner for a few seconds, than turns it off for a few seconds, lights the
burner....  Called Pulse Width Modulation in electronics.

- Backtalk version 1.3.30 - Copyright 1996-2006, Jan Wolter and Steve Weiss