Straighten a silver hammered coin

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Re: Straighten a silver hammered coin

Post by sweepstick47 » Wed Feb 20, 2019 9:10 pm

Although the deed has now been done so, I'll just proffer my preferred method which is to to roll the coin flat by using a series of graduated dowel rods, starting with the smallest diameter and progressing. I think any attempt at straightening silver coins has to be a personal choice, involving a good visual assessment to arrive at a possible solution as well as the probable outcome.

Probably not the outcome you would have wished for, but without experimentation all forms of progress would falter ::g Thanks for your report. Regards ss47


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Re: Straighten a silver hammered coin

Post by TheMellowedMole » Thu Feb 21, 2019 7:18 am

Shame that it cracked on you during your process of getting it straighted but at least now you (we/us) should have a better understanding of the limits of the process.
You done better than me i found a hammered coin the other day that i never got a chance to straighten as it just fell apart in my hand when i was wiping the mud from it before i realised that it even was a coin when i pulled it from the soil it looked like a bit of lead :(
Thanks for the post ::g

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Re: Straighten a silver hammered coin

Post by norfolk_booty » Thu Feb 21, 2019 10:26 pm

Thanks for sharing your experience on here, I've annealed using a blow torch with great success on Edward pennies with a high silver content and had a pretty appalling results with a posthumous Henry VIII/Edward VI groat (heavily debased).

I've also had great success cold straitening if the crease arn't too severe.

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Re: Straighten a silver hammered coin

Post by Ten pence! » Thu Feb 21, 2019 10:58 pm

The coin below was straightened by being annealed three times, any creaking or resistance during the straightening process and another blast with the blowlamp, it was cracked to start with but it was still in one piece when the job was finished, zapped for a few minutes to even up the colour and remove the scale and then toned with bleach, a coin fit for the scrap silver pot rescued.
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Re: Straighten a silver hammered coin

Post by Chilgrove » Wed Feb 27, 2019 10:54 am

Update: I thought I had ended up with a cracked coin. Wrong! I picked it up the other day, very gently, and guess what, it decided it would be happier in two pieces so now I will have to decide on the best way to rejoin. My two choices so far are the silver expert I know or to use what the museums use, HMG Paraloid B72 adhesive. I have not so far managed to see anything in this forum about rejoining 2 halves.

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Re: Straighten a silver hammered coin

Post by Allectus » Wed Feb 27, 2019 11:01 am

Chilgrove wrote:
Wed Feb 27, 2019 10:54 am
Update: I thought I had ended up with a cracked coin. Wrong! I picked it up the other day, very gently, and guess what, it decided it would be happier in two pieces so now I will have to decide on the best way to rejoin. My two choices so far are the silver expert I know or to use what the museums use, HMG Paraloid B72 adhesive. I have not so far managed to see anything in this forum about rejoining 2 halves.
Loctite super glue gel. ::g
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Re: Straighten a silver hammered coin

Post by targets » Wed Feb 27, 2019 1:40 pm

super glued some hammys and u can use silver solder if you have a fine torch and some silver solder to get em back together but best left to a metal worker if its worth it
' hammys how i love ya, how i love ya my dear old hammys '

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Re: Straighten a silver hammered coin

Post by Dangerous Norman » Wed Feb 27, 2019 4:24 pm

I had a silver hammered that already had a small crack, even the slightest pressure and I knew it was going to get worst. Anyway out came the blowtorch, a nice cherry red and dropped in water. A bit pressure to straighten it a bit then back to the blowtorch to repeat the process (I had been told that been told that straightening it too much in one stage wasn't good). After the third time I heated it to cherry red and allowed it to air cool. A gentle rub with a soft cloth and I now have a nice flat coin with plenty of patina and weathered silver look to the raised detail. It's how I would imagine it to be when in normal use rather than looking like it's been polished to a high shine.
MDF 00106 Edward I Hammered (reverse).jpg
You can see the small crack at the top, left of centre. During the straightening it didn't actually crack any more than it hade been before I started. I think I was lucky.
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Re: Straighten a silver hammered coin

Post by shaggybfc » Thu Feb 28, 2019 12:58 pm

My Eddy penny that was found completely bent in two. Debated whether to straighten it... but did in the end. 4 times annealed to dull red and quenched in water cycles and it straightened OK I guess. Stress marks can be seen running from 2 o'clock / 8 o'clock position
Before:
hammy2.jpg
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Re: Straighten a silver hammered coin

Post by Tronic5 » Mon May 27, 2019 10:03 am

Hi, just thought I'd add a bit of info regarding annealing silver. As a working goldsmith I hope I'm able explain the process. First things first you need to assess the coin or item and see how bad the bend is, no amount of annealing will help if the metal has stressed too much.

The process of annealing silver is carried out when the metal has been WORKED and becomes hard to bend or shape. The heat process used in annealing basically loosens up the molecules of the metal thus making it easier to work. This procedure is used multiple times when silversmithing as silver does work harden quite easily.

As previous posts have mentioned boiling water will not do anything. I would stay clear of a gas hob flame too. For best results annealing silver should be carried out on a heat proof block and with a hand held gas torch. The key thing here is to use the blue part of the flame not the yellow. Gently move the torch from left to right over the coin keeping the torch at the same distance. What you are looking for is the coin changing colour to a mid white pinky colour. DO not take it further to a bright white pink as this will be close to melting point. Once you have reached the desired colour I usually keep it there for a second or two, no more.

After annealing Jewellers usually quench silver and gold in a diluted acid bath called "Pickle" this will remove oxidisation. Once cooled you should be able to bend the silver gently with you fingers
Depending on the bend you could also use a hard rubber block with a Hyde mallet and gently tap it out.

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Re: Straighten a silver hammered coin

Post by targets » Mon May 27, 2019 2:50 pm

i found a rare chas1 shilling last week and it looked not right so a quick heat on the hob confirmed it was a tin snide as its started melting in blobs
' hammys how i love ya, how i love ya my dear old hammys '

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Re: Straighten a silver hammered coin

Post by Dangerous Norman » Mon May 27, 2019 3:19 pm

I found a silver hammered penny bent almost double. It already had a small crack on the bend and even the slightest pressure and I could hear it about to get worse.

It was either leave as is of give it the heat treatment.

In to the shed, lit up the torch, lights out so I could see it glow red and, with everything crossed that could be crossed I applied the heat. Got a dull red glow all over and in to water. Straighten it out carefully then before the final straighten I repeated the annealing process. Probably not necessary but I thought better safe than sorry. Last effort to completely straighten and a bit polish. I have a nice flat hammered coin with a patina.

Did the crack get worse you ask, NO it didn't so would I do the same on another silver coin. Yes I will and although I haven't needed to as yet I did the same on a squashed thimble with 2 or 3 small holes at the ends of some bend creases. Didn't risk attempting to remove the small dents which were quite angular but the thimble is now thimble shaped
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Re: Straighten a silver hammered coin

Post by Spearhead » Mon May 27, 2019 4:35 pm

Chilgrove wrote:
Wed Feb 20, 2019 4:25 pm
Those who thought I could make a mess of this have been proved correct. Tried today to straighten and although it is now flat, there are 2 cracks which were not apparent before. I thought I was being clever as there has been much debate about the best method. So I compromised by using our electric oven at max. (250 degrees C) then immersion in cold water to anneal. I was too apprehensive about using the gas torch and thought the oven would work even though I know it is much lower temperature required for 100% annealing process. I do know a local jeweller who makes her own jewellry so I have asked her to take a look at my mess. Should have left it to the pros.
Not the end of the world. A cocktail stick a steady hand and some silver grey epoxy putty will make the cracks almost invisible to the naked eye. When dry use the silver foil cleaning method to help the colour match. ::g
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