This 1865 3-cent nickel I got in a recent consignment has a rather bizarre appearance. At first glance, it sort of appears to have a massive strikethrough error on the reverse. But I know that’s not really the case. It has to be PMD (post-mint damage), or, as @paddyman98 says, a “DEFDAM”. (Definitely damaged). But it is rather intriguing damage, nonetheless. I’m at a loss as to what might have caused that localized area of (corrosion?) in that bizarre ovoid pattern, almost in the shape of a capital “D”. Eh. Who knows. Weird, and mostly worthless, but interesting, huh? Maybe acid-etched, but if so, the pattern is still rather baffling.
I thought about that, too. And that could well be the case, though I would normally expect to see traces of the solder still there. And for the traces of mounting to be nearer the middle of the coin. But I guess solder does seem the most likely scenario.
It was just three cents to them, back in the day. Nothing special at the time. And if you wanted to make a cufflink or whatever, it would have been cheaper than using a half dime, and you’d have a slightly bigger coin to work with.
Indeed it does, and I suppose that’s also possible, but I think I still subscribe to the solder theory (which, after all, would have still involved hot stuff being applied to the coin). The “D” shape might be coincidental. I think it’s probably random.
If solder was hot enough to melt nickel, I would too. But nickel’s melting point is significantly hotter than solder’s melting point
Perhaps the controlled acid treatment? I don't think that it's solder as the pattern is not that of raised additional metal. The obverse displays no flattening as one would expect from punching.
Even so, you have to get the nickel hot enough to accept the solder. What do you think is used in the electronics industry on connectors, circuit board pads, components, etc.? Nickel plated copper or a gold-nickel alloy. That's either the result of a cold solder joint, or, more likely, they used acid-flux solder like the kind you use in plumbing, and the acid based flux corroded the connection and it broke off. Look at how pitted the coin is in those areas. That's CORROSION. Even the obverse has a few pits in it. Back then, I don't think they had rosin flux or other non-acid fluxes like they do now. I've worked in the electronics industry for 40 years...
The more I look at it, the more I think that's solder. I do see excess metal in a few areas, like the rim at 9:00 on the obverse, and on and below the wreath at 6:00
It depends. Solder used for brazing has a much, much higher melting point than that used, for, say, electrical work. The type I use in my electronics work melts at around 360 to 370 degrees F. However, most techs, including myself, heat our irons at around 750 degrees to ensure a good connection, a little higher if I am using lead-free solder or have a large area to heat up. The connection has to be heated to the point where it will accept the solder, which means it has to be hotter than what it takes to melt the solder, otherwise you end up with a brittle, "cold" joint. It also depends on what you are soldering TO, don't forget that, (the ring or cufflink itself in this case) to get the joint hot enough. I am both J-STD-001 and IPC-A-610 certified.
I came into the electronics hobby well after the tube era, so the constraint was always "don't cook the semiconductors", which (in those days) didn't like to go much above 250 or so. But copper doesn't melt until almost 2000 F, and nickel above 2600 F. (It doesn't look like they form a eutectic with a lower melting point, either). But my understanding is that solder dissolves some of the copper (and presumably nickel) when you're forming a joint. Remove the solder, and some of that coin will come along, right? I'd guess, though, that acid flux is even more likely. Given that even vinegar will gnaw out the nickel from cupronickel, I'm sure hydrochloric acid/zinc chloride would chow right down on it.