Milk Spots- Are They Such a Big Deal?

I don't think so...?

There's PVC, of course, which is still widely used, and PVDC (Saran), which is falling out of favor partly because of environmental considerations around its manufacture. Other than that, how much is there? Polyethylene, polypropylene, polystyrene, ABS, PET -- most of the polymers are essentially chlorine-free. I doubt any of the TPG packages contain it.

 

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I always thought slabs were a polycarbonate, due to how tough they are, but I guess not. Hey, how about Pollyanna?

 

There are other potential sources of chlorine besides the packaging. The labels and the ink (especially lazer printing ink) that is printed on them can contain chlorine. Even the glue on a label can contain chlorine.

 

Thot I would add my two cents:
Imagine a conveyor belt moving thousands and thousands of silver planchets out of the drying ovens to meet the presses. They are shiney, and have just been washed with detergent (a soap, often with borax compounds). Occasionally some residue of the soap remains, it is almost invisible to any inspectors. The press stamps each planchet with (lets say with 100 tons) tons of pressure. The invisble residues are actually pressed INTO the metal of the coin, the small bit of detergent is now a part of the coins metal structure! It cannot be removed without removing metal from the coins surface. These milky whitish spots (see "Doug's ASE sun-with-rays, pic) are especially troublesome in the fields of silver proofs. The mints are aware of the problem. But it requires some extra time and effort to CAREFULLY dry and remove/rinse with clean distilled water, repeatedly to remove all of the residues. Heat, air drying, and even hand drying with clean towels are used. Some mints (such as the old Franklin mint) and the Perth mint rarely if ever released/release such ruined coins! The lazy and sloppy -- and usually busy -- mints should be held liable for selling such coins!! It is hard for a buyer to avoid such ruined coins, especially if the buyer cannot FIRST inspect the coins. Thus it is a gamble when ordering directly from the mints, or buying off auction websites. Such coins are part of a numismatics life. live with it!! And beware. The fiber cloth "solution" stems from a person who does not know what true milk spots are. I mean really -- rub a fiber cloth across the mirror surface of a proof ASE, you will leave hairlines. (see the period ...).
Gary

 

Desertgem - I did confirm that normally HCL dip is used and this is standard practice for treating silver making it non-corrosive to airborne elements. It could also be that traces are possibly left on the surface which of course is AgCl. A remote possibility. QC Inspection would catch this phenomenon. These high silver pieces simply need a better post-treatment anti-oxidant specific to this alloy's requirements. These milk spots of AgCl and other? Ag compounds possibly are being created after they leave the mint - IMO.
Like you said - we would need EVERY step of the production process. I would dig into this further in my lab but for what purpose? They will work it out.

JPL

 

IIRC the hydrochloric acid treatment was allegedly started back in 1921 which explains why the 1921 Morgans and Peace dollars and subsequent 90% silver issues tone differently that the 1904 and earlier coins. Where and with whom did you confirm the use of HCl? Where in the process is it used and removed? How is it removed? The incipient milk spots are already there simply awaiting for the right conditions to complete the reaction and make them visible. Since silver doesn't ordinarily react with HCL, then some other species must be the source of the silver in the AgCl. How does the HCl act as an antioxidant. Isn't that the purpose of the trace/s of copper which is/are present in ASEs? I expect that reaction with atmospheric contaminants is of more concern than reaction of the coin with oxygen.
Since you can't see the spots, how would QC inspection find them? I have seen it said/written that the incipient spots can be seen with the aid of a halogen flashlight BEFORE they become visible as the dreaded milk spot, but I have never been able to confirm this in practice.

 

You may find the linked video interesting.

 

I read this entire thread mystified that none of this was brought up yet.

 

It's hardly relevant to ASEs. The spotting isn't due to detergent/s.

 

But it is relevant to milk spots in general and the way that numismatists have considered them created for decades. Take a look at some Franklin half proofs for many classic examples of milk spotting.

 

Has it been established chemically that those spots are different than spots on ASEs or modern silver coins?

 

Thank you BAJJERAN for that video. Interesting. Believe me ASE's are washed with a chemical (or detergent) prior to stamping. I am not referring to the polishing stage, but actual washing and rinsing. But again thanks for the video, I think the guy is foolish to use jewelers cloth, and the erasure, both methods will ruin a proof coin to the discerning collector. Perhaps okay for a quick EBAY sell, but not for serious numismatic uses.
Gary

 

I think I did this right ,embedding a Utube file. But in this vidoe of silver rounds, it does show the washing step before the polishing step. After polishing the residues are practically invisible. They then will be impressed into the coin, be it silver, of CuNi or whatever. Hope this helps.
Gary

 

The serious numismatist will simply find unspotted coins. He did mention the use of borax which does not seem to be a contaminant on ASEs.

 

How common is spotting on silver rounds?

 

I simply offered a suggestion, which I heard somewhere, by a person who worked in a mint. He said it was probable that the cleaning residues were most likely stamped into the coins. Who he is, I no longer recall. It was offered for your considerations. I am not about to get into a time wasting argument over such a trivial issue. Its a fine day, yes?
Gary

 

Kinda cloudy n gloomy here, but we do need the rain. Otherwise it is a fine day. Regardless of what the spot material is, it is not added after the coin is struck so by default it must be on the planchet before it is struck. Whether the strike pressure contributes to its permanancy would, it seems, depend upon what it is. In the above video the milk spots are stated to be borax and except for the cloudy ammonia method which wasn't shown, appear to be easily removable. From what I have heard even the silver chloride based milk spots are easier to remove from proof coins than they are from business strike coins,which would lead one to believe that strike pressure is not a significant factor in the appearance of spotting. In the case of borax based spots a physical attraction is involved whereas for chloride based spots it's more likely the result of a chemical [often delayed] transformation.

Tom

 

I don't know and don't claim to. And neither you nor I know whether the spots on my coins imaged come off or not as they were returned to the Mint for having sent out inferior product to a customer. I let them figure it out. And so what you assume is your assumption alone, and unproven to posit that they are unrelated, as it an assumption not a proven.

 

On your pictured coin maybe , but I've had other proofs that looked like yours that I dipped and the marks disappeared and never came back . So I can make an educated assumption that the marks on your pics would like come off too .

 

There is scientific proof about why the sky is blue, yet none for what is or isn't a milk spot and you certainly haven't that proof to tell it from photos for which you have yet to provide evidence or any of your supposed knowledge about this topic, to suggest how you can tell.

People study a lot of things without gaining knowledge. Kids sit in school and the get accused of information going in one ear and out the other. And your 'sky is blue' example is further weakness in your argument in this thread, and further proof of your style of three card monte, slight of hand, argument in which you constantly try shifting the topic away from your erroneous.

Just admit it Doug, you're beat here. You're struggling to keep up your game and with each reply you stray further and further from sharing knowledge as you have professed for years and defer to others needing to look at coins. Guess, what. I don't take your words for granted. I do study, read and look at other milk spots on coins, and from my observations, readings and the lack of any supporting evidence you've provided find yours failing. Sure I can a scientist and many school kids to prove to me why the sky is blue, and when I do, I get an answer. When the same is requested of you, you do everything but stand up to your assertions that you are correct. You do everything but provide any proof that you have knowledge, let alone grounds to base your assertions on.
Squirm all you like. Go silent and say you can't get anywhere with this discourse, but the onus is on you since you suggested you have the knowledge and can identify this condition yet refuse to explain how.