Cold shut definition

[nealeffendi]

I mentioned to Fred that he didn't have cold shuts in his error/variety catalogue.
He had never heard of the variety and still thinks that it is just struck through coins.
Has anyone got a good description of how cold shut coins occur as I realised that I can't properly explain it to him?
Also I can't find that image that someone posted a few days ago of an early 1960s penny with a large chunk missing causing the opposite side to be weakly struck in that portion. That image proves that the cold shut isn't a strike through.
Anybody remember in which thread is the image?
Edit to add. Found the image (#984 Fridays photos)
Still need a good definition and explanation of the variety.

[trout]

I imagine that Fulvio (After he gets back from his afternoon swim in the money bin) will shed some light on this for you :good:

[Fordprefect]

Still need a good definition and explanation of the variety.

Simple, they are not a variety.
A cold shut flaw is unique to each coin.

[nealeffendi]

Still need a good definition and explanation of the variety.

Simple, they are not a variety.
A cold shut flaw is unique to each coin.

So how does this error occur?

[Fordprefect]

Still need a good definition and explanation of the variety.

Simple, they are not a variety.
A cold shut flaw is unique to each coin.

So how does this error occur?

Not an error a flaw.
It starts at the rolling stage of the planchet strip.
A manufacturing flaw in the planchet before being struck.
Fulvio will love this thread just hold on untill he comes back.:idea:
Added:
We in the coin world have been calling them Lamination Flaws

[Goldseeker]

May I suggest you Google "Cold Shut".

[markn]

I agree, it's a flaw or an error rather than a variety.  To my mind its either a piece of foreign material or cold metal that makes it's way into the rolling process.  The "cold metal" can sometimes be partially attached to the underlying material.  The foreign material or metal fails to bond correctly with the underlying metal while rolled and either falls out at a later period or is partially attached.  The best analogy I have is if you're kneading dough and you try to work in a bit of dry crusty dough that's fallen off.  Sure it'll flatten out but it will never bond correctly with the rest of the dough.

[nealeffendi]

I agree, it's a flaw or an error rather than a variety.  To my mind its either a piece of foreign material or cold metal that makes it's way into the rolling process.  The "cold metal" can sometimes be partially attached to the underlying material.  The foreign material or metal fails to bond correctly with the underlying metal while rolled and either falls out at a later period or is partially attached.  The best analogy I have is if you're kneading dough and you try to work in a bit of dry crusty dough that's fallen off.  Sure it'll flatten out but it will never bond correctly with the rest of the dough.

I followed Goldseekers advice and googled it. Your dry dough analogy is good Mark but you have the actual details wrong (no foreign material involved and it happens during casting and not rolling). So if Mark and I were both wobbly on the details I'm assuming that others are as well. For everybody's edification the details are:
Poor pouring technique lets 2 streams of molten metal meet with too low a surface temperature for them to fuse. The interface is a weak point that can later separate producing the cold shut error/defect.
Does that sound about right?

[Goldseeker]

No arguments from me.

[Fulvio]

I imagine that Fulvio (After he gets back from his afternoon swim in the money bin) will shed some light on this for you :good:

Hehe. And very refreshing it was too...

Actually, there's quite a thread here already on the subject, so no need to rehash it all over again, is there?

As to what you found with Google, most of the material out there refers to cold shuts in casting. Its a huge problem, and can produce defective parts that look perfect until they fail disastrously.

Our materials and processes are slightly different, plus we tend to include similar flaws that are not strictly speaking cold shuts. Like when you get a thin layer of impurities rolled in that later cause the surface to peel. I think Mark's dough example is quite good actually. Its all the same dough, but physically two distinct pieces cobbled together temporarily which will eventually part company once subjected to more stress than the weak bond can take.

[nealeffendi]

I should add I've done some more digging and there is also the metallurgical phenomenon known as cold shot (a type of cold shut). It is a globule of metal is encased in a larger body of metal.  That is the chunk of pie crust in the dough.

[runway]

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