1878 toned

if blue and purple is A toneing then look at this going on right now.http://cgi.ebay.com/1889-CC-Rare-Ra...dual?hash=item45ed8035e7&_trksid=p3286.c0.m14

 

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amen!!!

 

It is somewhat simplified to say that yellow -magenta -cyan is the progression of colors on a silver coin as it does not take into consideration when more layers are deposited over previous ones. This url indicates the progression through several cycles of deposit.
http://forums.collectors.com/messageview.cfm?catid=26&threadid=716279

The other links in this link's first posting charts the depth of the toning deposit and the ability of the human color receptors to interpret the thin film effect. It is difficult reading, but I think anyone doing so would have a better understanding of color progression.

Jim

 

I would just clean it up a bit and be happy with a nice MS45. Put in folder for 100 years and see what happens. Jim, great info on the sunnywoods system. Regards Traci

 

Thanks for the info, I didn't know that was the reason behind the effect. As for my post I wasn't saying that all NT coins have the shadow effect, just that if you see a coin with the "shadow effect" there is a very good chance it's a NT coin. I don't think it's possible to fake it, or is it? :bigeyes:

 

Job well done folks. I think the consensus was reached and the verdict is in.....AT all the way!
Nice check list Lehigh! That's why you're the Chief toning freak
But kudos to Tonedcoins for his wicked skills, you are a major player on the stage of oxidation!
As for the Morgan, now that's a horse of a different color..........looks like a box of crayons exploded on her! LOL

 

Captain Kirk,

Everyone's opinion matters and are considered!


Frank

 

Good desertgem.... it is the way toning happens, it's just the way the human eye sees the colors....

You're not always going to see all this beautiful colors but there are many nice specimens (neon) coins where you would see many of them and this is why this (neon) coins go for much higher than just your typical rainbow toned coins.....

raider34, you are welcome. If you were to study a toned coin with this (not perfect) struck coin up close. You will see a difference in the pattern on that struck area than the rest of the coin. If you look at a toned coin (Morgan) with this type of stars you will have a better understanding why the "shadow" effect happens.

Just the peel effect on that area changes the metal content which will tone differently which gives it the (shadow) effect... Now, not many people know this but I do hope people do a little more research with there next NT coin (Morgan) with this effect. You will see why this is why it happens.

It is almost like a broad strike on the (stars) like pictured below. That area alone will tone differently from the rest of the coin. It is because of the way the coin is struck and changed from the rest. Look around the "CA" area and you can see this similarities on the stars of a (Morgan) which gives it the "shadow" effect.

This is only my opinion and I have studied this for a while. ..

 

i dont think i will clean the coin up because i like the way it looks even if its A toneing. all toneing is from sulfur if its toned in a few min or 50 years its still a toned coin by sulful which is the same for N toneing also.

 

Rigo,

The shadow effect is real. However, the striking of the planchet does not cause the metal content to change. Rather the stresses in those areas are much higher which basically causes a localized area of the metal surface to become work hardened. Corrosion (oxidation/toning) occurs through process called diffusion. The work hardened area slows the diffusion process (corrosion) due to an increased number of dislocations in the crystalline lattice structure.

And I would like to thank you for jogging my memory from my college days. It is not often I get a chance to employ my metallurgy degree.

 

Lehigh96, sorry... I forgot that you were the pro here... But this is exactly what I tried to say including the "stress" on the area part, I just never went to collage like you...lol. I am simply a toned coin collector working as a Orange County Officer. But, from up close there has to be a change on the metal planchet once it is struck in such a way.The (Morgan is not 100% silver and when stress like that happens it changes from the rest of the coin in some way. Now like I said, this is my opinion.

You are welcome about me bringing your college memory back when learning how to be the metallurgy degree to be the expert at cointalk .... :eating:

Lehigh96, you can finish this thread buddy... I gave my opinion and experience... good luck.:hammer:

 

The planchet is a silver alloy. The striking process causes physical stresses on the planchet but there is no chemical reaction, therefore the composition of the planchet/coin can't change during the minting process. Work hardening has been used in many commerical applications on many alloys to increase corrosion resistance. However, in this case, it is purely coincidental.

BTW, I certainly meant no condescension in my previous post. You have a broad knowledge of toning and coins in general. And you are right that the coin changes from the rest of the coin in some way, it is just not a composition change. The localized work hardening around the stars, date, and letters changes the physical properties of the metal inlcuding the resistance to corrosion.

Here is an article about the negative shadow effect. Dick Johnson believes that every Morgan Dollar that exhibits the negative shadow effect has some tin in its composition. No way I am going to agree with that theory. Note that he skips the why part!

http://coinbooks.com/club_nbs_esylum_v12n09.html

The article is about half way down the list.

 

Lehigh, my understanding of the work hardening of silver ( for example) was to align the metallic crystals in such a way to decrease ductility and increase surface hardness and make it more resistant to chemical reaction such as toning/corrosion. I think this is what you said. In silversmithing, the hammering can leave part of piece of jewelry resistant to the patina solution, so it could come out patchy. This is overcome by gently heating the whole piece and "relaxing" the work hardening and then use the toning solution. Patina application is common in silver smith work. An older gentleman who does such work said that leaving the piece in the hot desert sun would heat it evenly enough to tone. With your background, do you think it could occur at 120-140 degrees? ( metal in the sun temperatures), which would eliminate the "shadow effect"? Wonder where he got tin??

Jim

 

The process of heating a metal to reduce the effects of internal stresses is called annealing. I know that the melting point of silver is very low compared to most metals but to accomplish annealing at 140 degrees F sounds a little implausible to me. The problem with using my background in relation to numismatics is that precious metals are not engineering materials and are not really studied at all by the engineering community. We spent all of our time in school dealing with steel, aluminum, copper alloys, nickel and chromium. No mention of silver at all.

I will say this. Every metal oxidizes more quickly at higher temperatures. Perhaps the increased heat is enough to cause the metal to oxidize despite the work hardening. I doubt that silver would undergo a change in ductility at that temperature though.

With regards to Mr. Johnson and tin. It sounds as though he is very experienced with tin composition medals. I didn't sound like the guy understood the science behind what he was trying to explain and he was mostly just using his experience.

 

There goes the neighborhood as I just joined up :-]

This one looks like a shake and bake to me.

 

I am quoting myself. What do you guys think of this coin.

 

Leigh that coin looks like the real deal. I post this not fully confident on my opinion.

 

I beleive I have seen this coin before in a tpg slab, maybe on herritage.com. I think it's the real deal. :bow:

 

Lehigh, I have been trying to map the colors according to Sunnywoods classification, and this one seems to follow a plausible progress of (I) which is 2nd cycle lemon yellow thru (Q) which is 3rd cycle blue-green. I see no interruptions or inserted colors, so I see nothing to say it is not NT. But I still stick to my belief that I can not 100% say it is either one.

If I was in the buying mood, I would chance it myself.

Jim

 

Anyone want to guess the pedigree?