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Re: [Shop-talk] Annealing Copper bars

To: Donald H Locker <>
Subject: Re: [Shop-talk] Annealing Copper bars
From: Jack Brooks <>
Date: Sat, 8 Aug 2020 22:50:49 +0000
Accept-language: en-US
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Thread-topic: [Shop-talk] Annealing Copper bars
Insulation - BINGO!  Great thought Donald!

I underestimated copper's heat transmission rate.  Using propane, I could not 
get a 1/8 x 1 inch x 8 inch bar to get to glow with the bottom of the bar 
clamped in a vice.  I decided to try "Insulating". 

I laid a 3 inch long copper bar (typical busbar length) across the teeth of two 
sections of a coarse hack saw blade clamped off to the side of my vice.  There 
is almost no contact between the copper bar and these supports, only across the 
tips of the teeth on the two halves of the hack saw blades, so maybe a dozen 
pinheads.  With this arrangement and with a partially-dark room, I could just 
barely see the red glow in the copper. After a quench, the copper bar was soft!

I now have a method.  Now I have to insure that I can clean up the contact 
surfaces well without affecting the flatness and I can go forward with 
softening the real busbars.

Thank you everyone for a fun adventure in learning,


-----Original Message-----
From: Donald H Locker <> 
Sent: Saturday, August 8, 2020 10:14 AM
To: Jack Brooks <>
Subject: Re: [Shop-talk] Annealing Copper bars

The temperature that the copper reaches is controlled by the rate at which the 
heat escapes it vs the rate at which heat is added to it, and finally by the 
temperature of the flame.

An oxy-fuel torch adds heat quickly, so the rate at which it is lost is less of 
a problem. Propane/air is not as hot as oxy/fuel, but they're both plenty hot 

I would expect a propane torch to do OK as long as your copper bar is 
reasonably well insulated from the outside world - how about [nearly] burying 
it in vermiculite? Add heat in the middle with the rest of the bar pretty well 
buried and it should get reasonably hot throughout. You could use a Tempil Stik 
or an IR thermometer near the ends to see when it has heated sufficiently.

It would be easy enough to then pick up the bar with pliers or tongs and dunk 

At least I'd try that before tempting the fates with Mrs. Jack's oven.
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On 2020-08-08 12:06 p.m., Jack Brooks wrote:
> I disagree to some extent on the water/oil quench vs. air cool, from 
> text and experience.  Iâ??ve done both with oil pan drain plug washers 
> and while there may be a difference, itâ??s minor making the two methods 
> interchangeable in my experience, especially if I am trying to go from 
> half hard to a softer condition.   A quench is the ultimate way to 
> soften, but just getting it up to temperature makes a huge difference 
> in hardness.
> The question remains, lacking an Oxy torch, thoughts on the clean 
> cycle of a home over or any other suggestions?  I may talk with my 
> body guy about using his Oxy torch.  That was a good suggestion.
> Thanks,
> Jack
> *From:* Shop-talk <> *On Behalf Of 
> *Pat Horne
> *Sent:* Saturday, August 8, 2020 8:44 AM
> *To:* John Innis <>
> *Cc:* shop-talk <>
> *Subject:* Re: [Shop-talk] Annealing Copper bars
> So, referring back to the OP about using the oven to anneal the bars, 
> it WOULDNâ??T be a good choice.
> Peace,
> Pat
> Pat Horne
> We support Habitat for Humanity
> On Aug 8, 2020, at 10:03 AM, John Innis < 
> <>> wrote:
> This matches my understanding as well.  Brass and copper soften when 
> quenched.  Steel and Aluminum harden when quenched.
> On Sat, Aug 8, 2020 at 9:59 AM Bob Spidell < 
> <>> wrote:
>     Could be (the plot thickens):
>     "Annealing copper makes it softer and less brittle, which allows you to
>     bend it without breaking it. This malleability allows you to hammer and
>     mold the copper into any shape you wish without cracking the metal. You
>     can anneal any grade and thickness of copper as long as you have a
>     flame
>     that can transmit enough heat to the metal. The most straightforward
>     way
>     to anneal copper is by heating it with an oxygen acetylene torch and
>     rapidly cooling it in water."
>     On 8/8/2020 7:43 AM, Pat Horne wrote:
>     > Maybe youâ??re right & Iâ??m wrong! Wouldnâ??t be the first time.
>     >
>     > Peace,
>     > Pat
>     >
>     > Pat Horne
>     > We support Habitat for Humanity
>     >
>     >
>     > On Aug 8, 2020, at 9:33 AM, Bob Spidell <
>     <>> wrote:
>     >
>     > Well snap. I've been doing it wrong all these years I've reused
>     copper, mostly on sealing washers for oil pan plugs.
>     >
>     > Thanks for the reply.
>     > Bob
>     >
>     >
>     >> On 8/8/2020 7:21 AM, Pat Horne wrote:
>     >> I thought quenching made the metal less soft.
>     >>
>     >> Annealing requires slow cooling.
>     >>
>     >> Peace,
>     >> Pat
>     >>
>     >> Pat Horne
>     >> We support Habitat for Humanity
>     >>
>     >>
>     >> On Aug 8, 2020, at 9:18 AM, Bob Spidell <
>     <>> wrote:
>     >>
>     >>  Question for the List: Is it proper to quench--in water,
>     presumably, or oil maybe--copper to achieve softness after it's been
>     heated 'cherry red?'
>     >>
>     >> Bob
>     >>
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