Should I try moulding it back into shape??

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Emily
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Should I try moulding it back into shape??

Post by Emily » Mon Feb 26, 2018 11:05 am

Found an undatable thimble yesterday which has been a little squashed over the passing years. I am considering heating it and then placing it slowly over a mould to get it back into shape.

Is this a good idea or will it wreck it completely?? Opinions please. :)
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Re: Should I try moulding it back into shape??

Post by Wormdigger » Mon Feb 26, 2018 11:12 am

I had one like that but with some cracks. I tried the heating method and it fell apart ;;z
It can be very brittle.
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Re: Should I try moulding it back into shape??

Post by Rhumours » Mon Feb 26, 2018 11:44 am

Honeatly I know nothing about metal detecting and precious little about what is found but ... I know a lot about annealing (heating up the metal to relax the molecules to make it maleable), so if you don't care about it go for it but ... if you don't know what metal it is the thin bits will ping off ... it will go black and it will probably fall part.

If you fancy a go anyway ... if you have a cooking blowtorch ... one of those small ones ... set the flame to just blue ..... wave it around the round end of the item first ... flicking at it. Don't get it glowing just till it plumes. ... try on a few 2 pence pieces you'll see what I mean .... goes a off dull colour .... and flick around the end .... too much it will pop and blister. ..too little and it will split at the thin opening ... and then .... after you think enough is enough .... 1 minute max .... leave it to cool on a lump of metal ... a hammer end or fire grate. The metal should. Now be annealed. Softer. Mealable. But don't take the p*@$.

Then find a bag of sand and stuff as much as you can into a garden gloved and tie up the end. It should feel like pushing against an appLe. Lay it down and get your thimble. You will need something round ended which will fit inside it. Like a wooden spoon handle. Get it in there ... tap gently inside ... against the sand filled glove. Little taps. After about 20 taos you'll need to aneal again. Keep this cycle up until you're happy with the shape or ... until your beautiful artifact is ripped asunder and you hate me :D

I know what I'm doing and I love how it looks. Genuine ... beautiful patina ... my last go at the metal detecting resulted in 5 feet if barbed wire ... 20 feet of electric fence .... two bottle tops .... one keyring fob thing .... a bag of crap I can't identify even .... and a bloody big hole that beeps like Indiana Jones should be running out of it .... I'd so love that thimble. ... ;)

Good luck - start watching from 4.30 minutes in.- https://youtu.be/gcoerxiIaMg
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Re: Should I try moulding it back into shape??

Post by fred » Mon Feb 26, 2018 1:00 pm

It probably won't straighten and if you try it will almost certainly fall apart. Even if the brass is OK the iron tops of these sorts of thimbles are usually little more than rust after a century or two in the ground. ::g
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Re: Should I try moulding it back into shape??

Post by Saffron » Mon Feb 26, 2018 3:07 pm

I think that is a great question, because I have some in exactly the same state and had thought about trying to straighten them out a bit.

I am sure that lots of other people also have thimbles in the same state, so we could all benefit from knowing the answer.

Would be interested in others thoughts about if we should risk it or not.

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Re: Should I try moulding it back into shape??

Post by Bargeman » Mon Feb 26, 2018 3:20 pm

Thimbles are quite a common find, so I see no reason in not practising your restoration skills on one, if it goes wrong, then you have learned by the error, no harm done.

And remember, the person that never made a mistake, never made anything


BM [:)


Edit for bad grammar.
Last edited by Bargeman on Mon Feb 26, 2018 4:06 pm, edited 1 time in total.
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Re: Should I try moulding it back into shape??

Post by fred » Mon Feb 26, 2018 3:48 pm

Bargeman wrote:
Mon Feb 26, 2018 3:20 pm
Thimbles are quite a common find, so I see no reason on practising your restoration skills on one, if it goes wrong, then you have learned by the error, no harm done.

And remember, the person that never made a mistake, never made anything ::g

BM [:)
Actually i agree with these sentiments entirely. ::g So perhaps wait until you have built up a few, decide which ones to keep 'as is' for you own delectation and then launch into the rest! :D
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Re: Should I try moulding it back into shape??

Post by Fusion » Mon Feb 26, 2018 5:12 pm

Thimbles can easily be re-shaped, thanks to the thin metal. Just anneal it ( do it properly; heat to dull cherry red, then quench in cold water, bend it some, then re-anneal, repeat, until it's how you want it.)
I found electricians needle-nosed pliers a useful tool for working on things like thimbles, use thick card between the pliers and the metal.

Re-patination is the main problem to overcome afterwards.
:(

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Re: Should I try moulding it back into shape??

Post by fred » Mon Feb 26, 2018 5:32 pm

Fusion wrote:
Mon Feb 26, 2018 5:12 pm
Thimbles can easily be re-shaped, thanks to the thin metal. Just anneal it ( do it properly; heat to dull cherry red, then quench in cold water, bend it some, then re-anneal, repeat, until it's how you want it.)
I found electricians needle-nosed pliers a useful tool for working on things like thimbles, use thick card between the pliers and the metal.

Re-patination is the main problem to overcome afterwards.
It will depend upon what has happened to the metal while it is the ground. If it has undergone dezincification or gone brittle through any of the myriad other strange chemical reactions that can take place in the soil it might not be quite so straightforward but probably still worth a try. ::g
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Re: Should I try moulding it back into shape??

Post by Easylife » Mon Feb 26, 2018 6:01 pm

The trouble is that you just won't know how brittle the metal is until you attempt to reshape it. Then when it quite possibly breaks you may wish that you had just left it as is. x;
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Re: Should I try moulding it back into shape??

Post by Rhumours » Mon Feb 26, 2018 8:53 pm

fred wrote:
Mon Feb 26, 2018 5:32 pm
Fusion wrote:
Mon Feb 26, 2018 5:12 pm
Thimbles can easily be re-shaped, thanks to the thin metal. Just anneal it ( do it properly; heat to dull cherry red, then quench in cold water, bend it some, then re-anneal, repeat, until it's how you want it.)
I found electricians needle-nosed pliers a useful tool for working on things like thimbles, use thick card between the pliers and the metal.

Re-patination is the main problem to overcome afterwards.
It will depend upon what has happened to the metal while it is the ground. If it has undergone dezincification or gone brittle through any of the myriad other strange chemical reactions that can take place in the soil it might not be quite so straightforward but probably still worth a try. ::g
Do not quench anything in water ... this makes the metal.brittle ... you must allow to cool naturally.
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Re: Should I try moulding it back into shape??

Post by Hawkeyes » Tue Feb 27, 2018 1:39 am

I have worked with metal most of my life and many exotic metals that most would not have heard of and this guy Rhumours is spot on you do not quench in water unless you want it to crack apart in fact the slower it cools the better this would be better done in an oven if you have one that will get hot enough as you can control the rate of cooling better.
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Re: Should I try moulding it back into shape??

Post by Easylife » Tue Feb 27, 2018 2:05 am

Thanks for the more precise annealing info guys. The plough bends the cast copper alloy items fine but then they seem to go brittle whilst laying in the ground. The slow and repeated method should have more success. ::g
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Re: Should I try moulding it back into shape??

Post by Wormdigger » Tue Feb 27, 2018 3:15 pm

Thanks for the great description of annealing Rhumours. Some things are just beyond that type of process. I'm with Fred on this one - I think that thimble will fall apart.
Having said that - practicing with some dispensable items is a great idea.
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Re: Should I try moulding it back into shape??

Post by Fusion » Tue Feb 27, 2018 3:46 pm

Quote:"Do not quench anything in water ... this makes the metal.brittle ... you must allow to cool naturally."
I disagree, that's why I made the effort to post here, stating the correct way to anneal.

But that's the problem with forums, ask how to do something, you'll get many different replies. Previous threads on straightening coins etc get all sorts of suggestions, from using 'hot water to soften the metal" ??? to those who would only consider bending the metal while it was glowing bright red.
:(

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Re: Should I try moulding it back into shape??

Post by Koala » Tue Feb 27, 2018 6:40 pm

Rhumours wrote:
Mon Feb 26, 2018 8:53 pm
fred wrote:
Mon Feb 26, 2018 5:32 pm
Fusion wrote:
Mon Feb 26, 2018 5:12 pm
Thimbles can easily be re-shaped, thanks to the thin metal. Just anneal it ( do it properly; heat to dull cherry red, then quench in cold water, bend it some, then re-anneal, repeat, until it's how you want it.)
I found electricians needle-nosed pliers a useful tool for working on things like thimbles, use thick card between the pliers and the metal.

Re-patination is the main problem to overcome afterwards.
It will depend upon what has happened to the metal while it is the ground. If it has undergone dezincification or gone brittle through any of the myriad other strange chemical reactions that can take place in the soil it might not be quite so straightforward but probably still worth a try. ::g
Do not quench anything in water ... this makes the metal.brittle ... you must allow to cool naturally.
Copper and its alloys can only be hardened by working them

Quenching does nothing to its hardness

People quench copper as the thermal shock removed most of the oxides and saves time


Quenching does harden high carbon steel

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Re: Should I try moulding it back into shape??

Post by Rhumours » Tue Feb 27, 2018 7:02 pm

I appreciate where you are coming from but you tend not to quench anything delocate in water ... as you have said .... because of thermal shock. But my post was made in the context of this thread of course .... and in particularly the OP. Thermal shock to that little thing will run the risk of splitting it. You might do it regularly and we all do what works.

Outside of this thread I have quenched many times. Not in water admittedly but sulphuric acid I believe it was ... was a few years ago now. Now it's pickle lol. As has been said water is used to quench to harden steel .... blacksmiths etc ... brimstone! Interesting thread too.
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Re: Should I try moulding it back into shape??

Post by Fusion » Wed Feb 28, 2018 3:09 pm

Quote:"People quench copper as the thermal shock removed most of the oxides"

The heating to dull red changes the crystal structure of the metal, to one more malleable and less brittle. The purpose of quenching is to 'freeze' this new crystal structure, the cold metal can then be bent/worked easily ( in moderation). If you allow the red-hot metal to air-cool, it gives time for the crystal structure to change slightly, into a harder, more brittle form. This is not desireable, especially having gone to the trouble of carefully heating the item in order to soften it.

It's not unreasonable to say that a very thin item such as Emily's thimble will air-cool fairly quickly, and maybe this effect is not so evident, compared to something more substantial, like a buckle.

Quote:"Thermal shock to that little [thimble] will run the risk of splitting it."

It does seem brutal, I agree, but in practice, it seems trouble-free, presumably because the heating process has removed the brittleness from the metal. I've straightened some severely bent and cracked hammered coins, involving multiple bending/annealing sessions, and they've all been a success, so far.

One mistake some people make is to be too excessive with their bending, which work-hardens the metal, making it brittle, and it cracks. Bend it just a modest amount, then re-anneal, and re-bend. I think it's fair to say if all goes well on the first annealing session, the repeat sessions will be trouble-free.
:(

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