Milk Spots on Silver Coins

[LawrenceChard]

I had never heard the term "milk spot" until the last year or two.

I think I first became aware of it on TSF, where there seem be be lots of discussions and complaints about milk spots, mainly about British Royal Mint silver coins including some high premium proof coins, and also bullion coins like Britannias.

This composite images shows milk spotting on a 2021 UK silver proof Queens's Beasts Black Bull of Clarence coin, one of 9 coins from a 10 coin Royal Mint set to feature this production defect.

Of course, I have seen white spots on silver coins before, but had never called them milk spots, or heard anyone else call them that, until quite recently as I just mentioned.

I can call to mind seeing a slight grey blue bloom on some silver proof crowns from 1980 and 1981. In the past, we have tried silver dipping a few coins, but with very poor results. I suspect that this bloom is caused by the same or a similar production problem.

A quick search using Google will find many pages discussing the problem, but none which states its cause, although a few of the sites including YouTube videos seem to claim to explain the phenomenon and its cause, but fail to actually do so.

A number of these sites mention that it might be caused by solvents or detergents used to clean the planchets (blanks). Some suggest PVC. Although PVC can and does cause some tarnishing, corrosion, or discoloration, I have never noticed it causing milk spots, so I think we can discount the PVC theory. My own thoughts were that it might be caused by oils or other lubricants, affecting either the blanks or the actual coins during the striking process.

The Royal Canadian Mint is to be commended because, according to its website, it carried out research over about 4 years, and in 2018 introduced something called MintShield, which reduces , slows down, or helps to prevent milk spotting. It proudly states that it now incorporates MintShield into its silver bullion maples, and other silver coins. However...

... Disappointingly, the RCM fails to state clearly what causes the problem, what MintShield is or how exactly it works, stating it is a secret process. While I can understand it protecting its investment in research to develop the process, I feel I should deduct points for choosing to withhold the basic facts, namely what is milk spotting, and what causes it.

As recently as yesterday, I asked our main Perth Mint contact what Perth Mint knew, as I cannot remember seeing it on their silver coins, although I feel sure somebody will have done.

I received the following very prompt reply:

Such spots are caused regularly by some small pollutions at the production process. TPM has made large efforts by cleaning the factory to prevent such spots.

I will check if there is any further “official” statement available about that theme from TPM.

Obviously, this does not explain everything we all want to know, but at least it is more than I have heard from any other mint, apart from the RCM as mentioned above. If I receive any further information, I will post it here.

 

 

 

[TeaTime]

Interesting.

I wonder if other mints are bothering to research the cause of this - i suspect that as long as there are customers willing to buy the coins then there is no incentive for them to do so...

As a long-time collector of RM silver proofs  i am always surprised at the number of people who complain about milk spots. I suspect some of them are new to buying silver coins and have unrealistic expectations. Every single silver coin minted will end up with toning or bloom. Not nice when it happens on a new coin but it will happen anyway, either next week or in a decade. As far as i am concerned the more collectors who sell silver coins at reduced prices because of spotting (and toning) the happier i am... Right now milk spots are a fact of life and expecting FDC coins every time is a recipe for disappointment.

Historically all oxidisation and 'bloom' was descibed as toning and i too had not heard it described as 'milk spotting' until recently. I suspect our transatlantic friends of 'coining' this phrase.

 

[LawrenceChard]

34 minutes ago, TeaTime said:

Interesting.

I wonder if other mints are bothering to research the cause of this - i suspect that as long as there are customers willing to buy the coins then there is no incentive for them to do so...

As a long-time collector of RM silver proofs  i am always surprised at the number of people who complain about milk spots. I suspect some of them are new to buying silver coins and have unrealistic expectations. Every single silver coin minted will end up with toning or bloom. Not nice when it happens on a new coin but it will happen anyway, either next week or in a decade. As far as i am concerned the more collectors who sell silver coins at reduced prices because of spotting (and toning) the happier i am... Right now milk spots are a fact of life and expecting FDC coins every time is a recipe for disappointment.

Historically all oxidisation and 'bloom' was descibed as toning and i too had not heard it described as 'milk spotting' until recently. I suspect our transatlantic friends of 'coining' this phrase.

 

Most toning or tarnishing on silver is caused by sulphides or other chemical in the atmosphere, although moisture is also required, generally in the form of humidity. Most chemical reactions also occure more readily and rapidly at higher temperatures. We could blame it on pullution and global warming.

Milk spotting does seem to be connected to production, almost certainly some chemicals in the processing of blanks or striking, and it's my view that it is not directly related to atmospheric polution. The RCM story would tend to confirm this view.

[sovereignsteve]

The RCM had to do something to be fair, as their record with milk spots over the last 10 years at least has been appalling. Their coins have been by far the worst affected.

[LawrenceChard]

13 minutes ago, sovereignsteve said:

The RCM had to do something to be fair, as their record with milk spots over the last 10 years at least has been appalling. Their coins have been by far the worst affected.

Yes, so I read.

It seems like they have passed that mantle on to the RM, so in another 10 years, we might follow!

[Bimetallic]

Yeah, it's disappointing that there's no real information or public research identifying exactly what milk spots are and where they come from. That's such a basic requirement for proceeding further, and yet we don't have it. It might take a motivated individual researcher to do the requisite testing and analysis, perhaps a chemist or metallurgist.

@TeaTime It's not clear if you're talking about milk spots. You seem to be saying that "toning", "blooming", and "milk spots" are the same thing, but that can't be true if "toning" is synonymous with "tarnish" as seems to be the case. Tarnish is caused by sulfur in the air. It's usually a shade of brown. Milk spots are not tarnish, they have a fundamentally different whitish appearance, and they are not cleaned by the methods that clean tarnish (e.g. the aluminum foil and baking soda method).

Moreover, it's not true that all silver tarnishes or that all silver develops milk spots. I've never had silver tarnish if I keep it in Ziploc bags, tubes, or capsules. And lots of silver doesn't develop milk spots. The nature and cause of milk spots are currently unknown to the public.

It's a tough problem because these mints are government mints and their employees are government employees. This creates a dynamic that breeds complacency and entitlement, and a lack of accountability or the strong customer service mindset common with private-sector enterprises. The Royal Canadian Mint is the most business-like of them all, and mints coins for lots of countries around the world. They're very innovative with both their circulation coins and bullion. The (British) Royal Mint is maybe in second place on innovation, and they also compete for business minting other countries' coins. The US Mint has by far the most money/revenue of the world mints, but they don't do anything with it. They're the worst of the major mints in terms of quality and innovation – they have no security features, trail behind on purity, and their circulation coin production is extremely inefficient and uninnovative (still using precious copper and nickel as base metals...)

It would help if the US Mint and others rolled up their sleeves and did some simple research on the milk spotting phenomenon, the chemistry, etc. It's not rocket science. But these organizations seem to be extremely complacent and unaccountable. They don't really communicate. They don't even respond to emails sometimes. I wonder if a private mint will do some research, like Sunshine or Scottsdale. Their products aren't collectibles though, not like the proof, ultra high relief, memorial, historical, baseball champion something or other that the government mints issue. It's just so hard to get real communication from the government mints. Even major dealers like Chards don't get much of a response, and we live in a culture where it's normal for organizations like this to have people on staff who issue nonsense answers to questions for a living, PR people and so forth. Clear communication is increasingly rare.

[silenceissilver]

4 hours ago, LawrenceChard said:

Such spots are caused regularly by some small pollutions at the production process. TPM has made large efforts by cleaning the factory to prevent such spots.

I will check if there is any further “official” statement available about that theme from TPM.

Obviously, this does not explain everything we all want to know, but at least it is more than I have heard from any other mint, apart from the RCM as mentioned above. If I receive any further information, I will post it here.

I have watched one video on Youtube about the Austrian Mint where they proudly state that their gold and silver productions are completely separated, with separated ventilation systems, in order to avoid pollution - little dust of one metal on the other - which is or at least can be responsible for red spots on gold coins as far as I know. I have no clue if this is standard for all big mints and just mentioned as a PR message or if this makes them stand out. In any case the Austrian Philharmonic silver coin does milk spot, I only have a few but I have seen it on them, quite badly on one, more milk than silver. Thanks God I bought this particular coin for someone else 

4 hours ago, LawrenceChard said:

A number of these sites mention that it might be caused by solvents or detergents used to clean the planchets (blanks). Some suggest PVC. Although PVC can and does cause some tarnishing, corrosion, or discoloration, I have never noticed it causing milk spots, so I think we can discount the PVC theory. My own thoughts were that it might be caused by oils or other lubricants, affecting either the blanks or the actual coins during the striking process.

I thought it must be one of these things too and was wondering why it couldn't be rinsed off - maybe it would take too much rising and thus increase the costs or maybe it could leave tiny scratches - or maybe it wouldn't be possible to rinse if off in the first place, depending on what exactly it is.

4 hours ago, LawrenceChard said:

The Royal Canadian Mint is to be commended because, according to its website, it carried out research over about 4 years, and in 2018 introduced something called MintShield, which reduces , slows down, or helps to prevent milk spotting. It proudly states that it now incorporates MintShield into its silver bullion maples, and other silver coins. However...

It's my understanding - actually I'm pretty sure - they don't remove whatever is causing the milk spots but there is a very thin layer of a chemical added, all around the coin that prevents whatever the milkspots are from becoming visible. I thinks someone mentioned it in God knows which thread, there is a company that colours also the Maples and in order to do so they have to get rid of this extra layer of chemical, so they can spot again. They are literally camouflaged, not removed - still better than not camouflaged.

Edited August 18, 2021 by silenceissilver

[TeaTime]

All marks that appear on untouched silver are caused by a chemical reaction.

I'm not saying that they are all the same thing (my post didn't say as much) but they are all caused by an interaction between the silver and a chemical agent. I think that the first two are a natural result of the properties of silver when exposed to the air (and the various sulphides therein). My belief is that milk spotting occurs due to surface contaminants because of how it manifests. That also seems to be the majority opinion.

However;

I've had Perth Mint coins that show milk spotting well over a year after purchase. I would expect milk spots (if being caused purely by contaminants) to show pretty much immediately (refer to the recent Queens Beasts proof sets debacle), not 12 months later. The only conclussion i can come to is that atmospheric conditions are also a part of the problem with milk spotting.

We all agree that milk spots are unsightly and we would all prefer spot-free silver. Realistically though, it's a long way off if even possible.

 

 

 

[goldhunter]

Is it just me or do these milk spots look like dried ejaculant?

[TeaTime]

In the case of my Britannias it may well be..... Although i think the 2021 proof version should be ok.

Edited August 19, 2021 by TeaTime

[LawrenceChard]

9 hours ago, goldhunter said:

Is it just me or do these milk spots look like dried ejaculant?

Come again?🦻

[LawrenceChard]

We have a customer who asked the Royal Mint about milk spotting.

Although I do not know his exact question, this was the reply he received:

Dear xxxxx,

 

Thank you for your email.

 

Please see response below, this has been approved by the relevant department regarding your enquiry below:

White spots or milk spots are occasionally found on the surface of silver bullion products and do not affect their value, as the silver content will remain unaffected.

The spots can develop over a period ranging from weeks to years and can be the result of a number of factors including microscopic chemical surface contamination during the manufacturing processes or incorrect handling & storage of the products where oils or moisture from hands/fingers reacts with the surface of the Silver. Safe handling and storage can greatly reduce the likelihood of white spots occurring. During our manufacturing process we take all precautions and adhere to rigorous quality standards to ensure that we reduce the possibility of introducing milk spots.

Any attempt to clean or remove the white spots is not advisable as this can introduce further contamination and scratches on the surface of the products.

As milk spots do not damage or erode the silver content, the intrinsic value of the silver is not effected (sic), you will, however, have to speak to the dealer for details of their refund policy as we are unable to advise on their policies.

If you have any enquiries, please do not hesitate to contact us,

 

Kind Regards,

 

It seems to me that someone at the Royal Mint does not know that it also occurs on silver proof coins.

It is misleading of the the RM to state that milk spots do not affect the value of the coins.

I do not think milk spotting occurs as a result of post-production handling, although it might be difficult to prove this either way.

While the intrinsic value of the silver is not affected, I suspect there will not be many TSF members who would be happy about milk spots, and most would say that it detracts from the aesthetic value, and market value.

I suspect our customer was asking about a Royal Mint coin, which he probably bought from them.

All in all, I think this is a rather unsatisfactory answer, but not totally unexpected.

[Rll1288]

17 minutes ago, LawrenceChard said:

We have a customer who asked the Royal Mint about milk spotting.

Although I do not know his exact question, this was the reply he received:

Dear xxxxx,

 

Thank you for your email.

 

Please see response below, this has been approved by the relevant department regarding your enquiry below:

White spots or milk spots are occasionally found on the surface of silver bullion products and do not affect their value, as the silver content will remain unaffected.

The spots can develop over a period ranging from weeks to years and can be the result of a number of factors including microscopic chemical surface contamination during the manufacturing processes or incorrect handling & storage of the products where oils or moisture from hands/fingers reacts with the surface of the Silver. Safe handling and storage can greatly reduce the likelihood of white spots occurring. During our manufacturing process we take all precautions and adhere to rigorous quality standards to ensure that we reduce the possibility of introducing milk spots.

Any attempt to clean or remove the white spots is not advisable as this can introduce further contamination and scratches on the surface of the products.

As milk spots do not damage or erode the silver content, the intrinsic value of the silver is not effected (sic), you will, however, have to speak to the dealer for details of their refund policy as we are unable to advise on their policies.

If you have any enquiries, please do not hesitate to contact us,

 

Kind Regards,

 

It seems to me that someone at the Royal Mint does not know that it also occurs on silver proof coins.

It is misleading of the the RM to state that milk spots do not affect the value of the coins.

I do not think milk spotting occurs as a result of post-production handling, although it might be difficult to prove this either way.

While the intrinsic value of the silver is not affected, I suspect there will not be many TSF members who would be happy about milk spots, and most would say that it detracts from the aesthetic value, and market value.

I suspect our customer was asking about a Royal Mint coin, which he probably bought from them.

All in all, I think this is a rather unsatisfactory answer, but not totally unexpected.

It seems to me then they should sell their bullion coins closer to "spot" if they think it doesn't affect the value... as we, in the UK pay a hefty premium above it (including VAT).. Maybe we should charge them VAT (Vanquish All Tarnish) when we buy them 🙂

[silenceissilver]

4 hours ago, LawrenceChard said:

I do not think milk spotting occurs as a result of post-production handling, although it might be difficult to prove this either way.

If it was a result of handling it after it was minted, you'd see it on old silver coins as well. I've only got a handful or two that are older than 100 years but I have also never heard about it, so I assume it doesn't exist for those coins but you'd know much better as you must have dealt with many, many thousands.

[LawrenceChard]

24 minutes ago, silenceissilver said:

If it was a result of handling it after it was minted, you'd see it on old silver coins as well. I've only got a handful or two that are older than 100 years but I have also never heard about it, so I assume it doesn't exist for those coins but you'd know much better as you must have dealt with many, many thousands.

We both share the same impression.

I suppose it is possible, but I am certainly not convinced.

[StackemHigh]

34 minutes ago, silenceissilver said:

If it was a result of handling it after it was minted, you'd see it on old silver coins as well. I've only got a handful or two that are older than 100 years but I have also never heard about it, so I assume it doesn't exist for those coins but you'd know much better as you must have dealt with many, many thousands.

I was under the impression that fine silver is most at risk of milk spots at 999.9 but with sterling silver or 500 silver milk spotting is negligible.

[Arcadian]

A quick Google suggests it's caused by leftover traces of borax, used in the manufacturing process.  I don't know if this is true, but it might explain the random nature of spotting.

[silenceissilver]

12 hours ago, StackemHigh said:

I was under the impression that fine silver is most at risk of milk spots at 999.9 but with sterling silver or 500 silver milk spotting is negligible.

That could be an explanation of course although I don't have any 500 silver but of course it's not 3 or 4 nines either - my old coins.  Honestly, I very much doubt it though that it has much to do with the purity. It's obviously one or another chemical that is used in the minting process. It it came from handling it, you would see it on Sterling silver as well, most likely.

[LawrenceChard]

13 hours ago, StackemHigh said:

I was under the impression that fine silver is most at risk of milk spots at 999.9 but with sterling silver or 500 silver milk spotting is negligible.

It is unlikely that fine silver would be worse affected than lower finenesses such as 925 or 500.

It is probably that many modern silver bullion, collector, and proof coins are made using 999 silver, which buyers expect to be perfect, so they get scrutinised more than older circulation coins.

Much of this evidence is anecdotal, but I believe that a large enough sample of anecdotal evidence can become statistically significant.

My experience, and a growing consensus, is that the problem seems to be caused by some contaminants from modern production processes, which presumably were not as prevalent in previous production processes.

 

40 minutes ago, silenceissilver said:

That could be an explanation of course although I don't have any 500 silver but of course it's not 3 or 4 nines either - my old coins.  Honestly, I very much doubt it though that it has much to do with the purity. It's obviously one or another chemical that is used in the minting process. It it came from handling it, you would see it on Sterling silver as well, most likely.

I agree.

[LawrenceChard]

1 hour ago, Arcadian said:

A quick Google suggests it's caused by leftover traces of borax, used in the manufacturing process.  I don't know if this is true, but it might explain the random nature of spotting.

Thanks for that input. I guess you mean the page on "Bullion Exchanges", which I have now read.

It may be correct, and sounds well written, but I am not totally convinced yet. 

If it is borax contamination, it should be quite easy for most mints to mitigate the problem, and there may be other contaminants.

I will continue to try and get expert opinions, which I will post here.

Any other input is welcome.

[LawrenceChard]

18 hours ago, Rll1288 said:

It seems to me then they should sell their bullion coins closer to "spot" if they think it doesn't affect the value... as we, in the UK pay a hefty premium above it (including VAT).. Maybe we should charge them VAT (Vanquish All Tarnish) when we buy them 🙂

Yes, perhaps we need a new, revised, definition of "spot price!" 🙂

[LawrenceChard]

On 18/08/2021 at 18:58, LawrenceChard said:

As recently as yesterday, I asked our main Perth Mint contact what Perth Mint knew, as I cannot remember seeing it on their silver coins, although I feel sure somebody will have done.

I received the following very prompt reply:

Such spots are caused regularly by some small pollutions at the production process. TPM has made large efforts by cleaning the factory to prevent such spots.

I will check if there is any further “official” statement available about that theme from TPM.

Obviously, this does not explain everything we all want to know, but at least it is more than I have heard from any other mint, apart from the RCM as mentioned above. If I receive any further information, I will post it here.

 

A brief follow up from my Perth Mint contact said:

"We focus on keeping a very clean environment to avoid white spot on our coins".

So this is very close to my answer earlier.

[KevinFlynn]

I'm learning to leave my tubes sealed 😯

What is the trust value on originally sealed tubes in private to private trade?

I talked to a professional seller and they said they would open the seal to make sure the content is what it says it is (kind of defeats the idea of the seal, but who knows).

 

Edited August 20, 2021 by KevinFlynn

[TeaTime]

Random thoughts;

I don't believe that surface contaminants have increased in modern times - just the opposite in fact. So that leaves a change in how coins are produced as the culprit. Any mint should be easily able to identify when a process change happened. If they believe it's a modern phenomena and had the will to do it...

Maybe it's a simple case of quality control - spotted proof coins that would have historically been melted are now deemed suitable to be sent out to the punters. As for milk spots appearing post-production - could it be that natural toning of the coins hid the underlying spotting issue ?

Bullion coins - could it be that historically no-one collecting silver bullion actually cared about surface blemishes ?  Is this pre-occupation with receiving flawless coins tied to the massive premiums we now pay ? Does speculation play a big part in expectations ? Have increasingly higher minting standards (and increased use of mirror-like fields) encouraged collectors to become more fussy ?

Until someone can pinpoint when milk spotting first manifested on silver coins then an answer wont be forthcoming.

Perhaps the real issue is why do milk spots appear so quickly in modern times when, historically, it took years ?

 

 

[zxtm99]

On 18/08/2021 at 22:58, Bimetallic said:

....It would help if the US Mint and others rolled up their sleeves and did some simple research on the milk spotting phenomenon, the chemistry, etc.....

I would be willing to bet that all the mints have looked into this very carefully. My suspicion is that some part of the minting process was reduced in cost by doing it differently, but a side-effect was milk spots. If a mint could nail the problem, they would not willingly share that knowledege as it gives them a competitive advantage.