Intermediate Quiz: What caused these marks?

expat, posted: " have a Morgan 1902-O Vam 26 with similar marks but they have been described as "Polishing Bands"

LOL, by whom?

 

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Randy Abercrombie, posted: "But I will take it one step further and suggest the coin was dipped to remove the discoloring."

Bingo! I will expand on this later and post images Tuesday that are on my computer at work. This was a difficult quiz because the marks resemble a lot of things.

 

By whomever put the descriptions to the pages. Look at the images till you find the top of the reverse
http://vamworld.com/wiki/1902-O_VAM-26

 

eventually, PVC forms acid that etches the surface of silver coins. So maybe this coin was in some kind of a pvc holder that had ridges contacting the coin in the area of the marks. Just a thought.

 

Sorry, the marks on the image you posted look NOTHING REMOTELY like the marks in the OP. Does anyone wish to disagree?

 

I agree. These bands (on the 02-O VAM 26 page) come from the die being slowly abraded while in service and are smooth and shiny.

 

I agree that it looks like tape or other debris that ate into the surface and then was dipped off basically environmental damage. A rubber band could be the cause too as they cause a black terminal Toning streak that can be difficult or impossible to remove

 

These marks were caused when black srteaks of terminal oxidation caused by (?? I was not there.) were removed. The surface was turned back to a silver shade of color but the surface under the corrosion was terminally etched. This type of mark is the only evidence that usually remains on a terminally toned surface (Black) when the coin is PROPERLY Cleaned.

I'll post photos of terminal toning streaks that will leave the same mark on Tuesday.

Note: The surfaces and overall appearance of a corroded surface, strike thru, planchet flaw, or PMD are different. This quiz is tough because it has characteristics of a strike thru or planchet flaw. I'll post some additional images of these characteristics as quizzes until the difference becomes easier to see. It is better for everyone if you know the answer (like Paddy in this case) that you KEEP IT TO YOURSELF so more members will have a chance to think the problem through until someone gets the answer.

It is no fun and a big waste of time for me if I post a quiz that is answered in the first or second post. So if I post PMD and you know it , please let the quiz run for a while. I'll keep it moving with questions to encourage posts from the "lurkers" until we get an answer. Thanks for letting me have some fun too.

 

Thanks for the education.

 

Wow, quite a different thread here than on a certain other forum.

A thought occurred to me while reading this thread - it is unusual to see toning in a streaky pattern like that. However, it is somewhat common to see grease stripes (black streaky marks). Could this have some from a grease strike that was removed? Something like this:

 

I’m curious, how do the affected areas respond to secondary toning? Are they resistant? Do they tone more easily?

 

Thanks for the info!

 

Yes, I am familiar with tab toning. Sometimes, it can be quite attractive.

In the case of the current coin under discussion, I suspect (if it is due to deep toning that was removed, that the "rubber band" toning theory might be more correct.

 

I see horizontal lines, similar to the woodgrain appearance you sometimes see in cents. I believe that's an improper alloy mix, right?

 

Thanks

 

Interesting... for a time I was accumulating 3 pence coins (cute little buggers) and ran into this one with a discoloration. I tried a quick, gentle wipe with a cotton swab moistened with eZest, and it did nothing. I applied a drop of eZest and let it sit with no difference I could see.

 

I guess to leave scars marks like this, it would have to have a corrosive in contact with the coin like a rubber band. Other black spots that would leave these kinds of scars that would be from dip residue, spittle, sneezle, and what not would have a different shape. Terminal toning not from contact wouldn't have well-defined borders.

So how to tell between this and a planchet flaw? I imagine the luster of the coin might be an indicator. The full-coin picture looks as though it could be... well... anything. One thing about planchet flaws this shape is that they often have black inclusions smeared through them, and those aren't coming out. Of course, they really don't have to, so I guess looking at the marks in context with the rest of the coin would give you a pretty good idea what you're looking at.

 

Anything is possible. Removing the streaks from the Bust half would leave a completely different surface etch.

Who knows? I've never tried to artificially tone a corroded spot.

No. Answer above.