(slightly OT) copper disc source?

for a quote you could ask

they list round bar upto 4" dia, but other stuff is available. Id expect it to be spendy tho (~=A3100 as a guess)

Dave

Well it's plate you're after not bar but anyway. Aluminium also has a very high thermal conductivity and a slice cut out of a plate of that would be much easier, and cheaper, to obtain. I doubt many people stock copper plate

6mm thick and fewer still would ever have a need for bar 7" in diameter. Any firm that does laser cutting will have aluminium plate suitable for your needs.

As an aside it's interesting that brass, despite being mainly copper, has a relatively poor thermal conductivity. Not much higher than the zinc it's alloyed with.

While copper is the best material, it's also the most difficult to source. How about a cast iron plate? A suitable car flywheel can be machined to suit and would cost very little. Also remember that one of the major advantages of gas cookong is the rapid response to flame change. A large heat sink will change all that.

John

bugbear wrote:

-- Peter Fairbrother

Oh, you might look for a copper gas kettle and cut the bottom off - they have fins on the bottom to improve the transfer of heat.

-- Peter Fairbrother

Yes - I suspect that cutting a circle from plate is far more likely - I was being slightly facetious with my slice-of-an-enormous bar concept.

Indeed, but substantially inferior to that of copper.

Auminium is my fall back option if my dream of copper comes to naught.

BugBear

Yes - but sometimes you want a slow, uniform simmer.

Whilst I can't make an electric hob quick, my proposal makes a gas hob slow, giving me (sort of) then best of both worlds.

BugBear

Hmm. Given the cost of copper, and the laws of physics, an Alu plate of twice the thickness may be cheaper (and have the same heat conductivity) as a copper plate.

It's the difference betweem heat conductivity of an object and specific heat conductivity of a substance.

BugBear (with options)

Most kitchen shops sell perforated double-skin steel ones that last about 3 years and cost a few quid. They work well and for me at any rate I've got better uses for my time. hth

Why make one when there are commercial ones available at only a few pounds.

Have a look in John Lewis, Debenhams etc.

It does so at the expense of fuel economy. The bigger the lump of metal you need to heat up before the heat permeates to the pan, the more fuel you will use.

Cliff Coggin.

On a 2 hour stock simmer, the extra (e.g.) 5 minutes to overcome the heat capacity of the plate seems a tolerable overhead.

BugBear

They work "fairly" well; I'm on my fifth. They're £2.50 from my ocal (excellent) hardware store.

Perhaps I haven't :-)

BugBear

Would a slow-cooker work ? Or a standalone induction hob ?

-adrian

Both have merit, but do different jobs.

With a slow cooker, if you want to pre-brown the meat, you need a separate vessel.

Induction hobs don't work with all cookware.

(in passing, slow cooking is quite easily achieved with cast iron cookware in an oven. Further, saucepans that are simply MADE of copper are available, and very good, but monstrously expensive)

With my (indulgent) idea, I can brown the meat in a "normal" pan, and then slow simmer on my copper-plate.

It's just a whim, and cheap enough that I may well indulge it.

BugBear

Yuck. Further reviewing of that page reveals that many common Alu alloys have heat conductivity far inferior to pure Alu.

BugBear

On or around Fri, 25 Apr 2008 10:23:18 +0100, bugbear enlightened us thusly:

we've got some, but they go rusty and crappy-looking rather fast. Copper plate would be nicer. I was thinking about a solid steel one.

Ah - I missed that; my little perforated ones are aluminium.

BugBear

On or around Fri, 25 Apr 2008 14:41:54 +0100, bugbear enlightened us thusly:

Alu would make more sense. I shall invest, I suspect. the steel ones looked nice initially but whatver they're coated with is not gas-fire-proof.