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Problem annealing large table top copper sheet

I am making a copper topped coffee table. It is 26" X 52" using 32 oz. roofing copper. I have hammered the entire sheet to get handcrafted look. Naturally it has curved up. In trying to anneal it I don't think I got this entire sheet "red" hot. I'm using propane torch. Do I need to get copper totally "red" hot so to anneal?

Rick De Troyer
artist - Chelsea, Michigan
2006

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First of two simultaneous responses -- 2006

Annealing copper depends on both time and temperature. 1000F will anneal copper in seconds, 350F in an hour. Copper conducts heat so well, that I think it will be difficult to get and keep it hot enough with a propane torch. Ideally you would put it in an over for an hour @ 350F. It could be loosely rolled up to fit. Got a friend at a pizzeria?

Jeffrey Holmes, CEF
Spartanburg, South Carolina

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Second of two simultaneous responses --

You are going to oxidize the copper to several colors if you use a torch. To correct the warping, turn it over and hammer the backside as required to get it to go dead flat.

James Watts
- Navarre, Florida
2006

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To Jeffrey Holmes or whomever else may have the knowledge ~

I tried annealing a sheet of 14-16 Ga. copper in a 350 degree oven for two hours in the past only to have it come out with rainbow colors but still very very hard. Can you tell me where I've gone wrong?

Dick Tracy
- Grand Rapids, Michigan, USA
2007