Easy / Cheap Chemical Removal of Milk Spots - Does it Work ?

[Pete]

I was browsing recently with regard to cleaning archaeological / museum types of ancient coins.
Various methods have been used, some with better success than others.
Ancient coins that contained a mixture of copper and silver didn't fare well using many techniques because of the copper.

My thoughts moved to modern pure silver coins and the dreaded milk pox.
There have been numerous comments regarding milk spots and milk stains on our popular bullion silver.
Nothing seems to remove them ( including eZest that strips everything else rapidly ) and the best results involve surface abrasion of some sorts, whether using a rubber eraser or ultra fine polishing.
Any mechanical rubbing will introduce microscopic surface damage but on cheap bullion does anyone really care ?
I've polished out some dreadful spots using a soft buff, jeweller's rouge compound and a Dremel to great effect.
Nice shiny beats clouded / spotted especially if the value is just the weight of silver and nothing more.

I researched a little more and came across 2 chemicals - sodium and ammonium thiosulphates.
These white crystalline compounds are safe, non toxic and readily dissolve in water.
Through chemical processes I believe ( but yet to be tried ) a solution of either in theory should dissolve without damage, the milky compounds on pure silver.

Before I experiment, if I do, has anyone already given these compounds a go and did you succeed ?
From what I read ammonium thiosulphate seems to react quicker with less concentrate than its sodium equivalent but costs 2 -3 times as much.

I've seen sodium thiosulphate listed on eBay for £6 per 200g delivered so relatively cheap.
You would maybe try mixing 1 part to 2 water and submersing a badly stained coin in the solution for 24 - 48 hours before rinsing.

Anyone got any experience ?
There was a forum member that was very knowledgeable on chemistry and seemed to have access to a laboratory and all chemicals.

 

 

[blindguy]

i was told that milk spots was soap residue left on the blanks and when the coin is struck the soap is pressed into the metal with so much pressure that it can not be removed. if the spots on your coins came after the coin was minted then maybe. the milk spots i was talking about were on proof franklins and proof kennedys.

[Tattoedamat]

I posted a topic a couple of weeks back using sodium bicarbonate solution although it helps with tarnish won't completely remove probably much safer to use than anything more aggressive

[Auricsstash]

I got mine out of storage recently, large number of brits from 2017 onwards and a pile of QBs I noticed a few were beginning to show the very early stages of spotting so I gave them a bath in hot water and washing up liquid seems to have done the job...

[Arganto]

I seem to be resurrecting necro-threads, sorry. However, it seemed a better option than starting another "can I clean my milky milks with...". Did you ever try the ammonium thiosulphates @Pete? I've read a few posts and watched a video extolling the virtues of Ammonia Hydroxide applied gently with a cotton ball, I was thinking of giving this a whirl as the common weaker solutions (~9-10%) are relatively cheap. Have you any knowledge of this?

Cheers for the time, and sorry again for the zombie!

[sovereignsteve]

I have tried a quite strong solution of sodium thiosulphate but no joy.

I didn't think to try ammonia. I have some strong stuff somewhere so will give it a go. It will clear my sinuses if nothing else😁

[DarkChameleon]

Anyone figures this one out then patent it cos you'll be a millionaire.

[HillWalkerDundee]

On 16/04/2020 at 12:40, Auricsstash said:

I got mine out of storage recently, large number of brits from 2017 onwards and a pile of QBs I noticed a few were beginning to show the very early stages of spotting so I gave them a bath in hot water and washing up liquid seems to have done the job...

That would add some weight to the earlier comments that milk spots were soap based.

[Arganto]

I've still to acquire the ammonia hydroxide, I'm definitely going to try it as a couple of coins I recently bought have some very bad milking so they can't look any worse. I'll post here once I've had a go. The issue with it washing off with dish soap would seem to be that the detergent would have been 'baked' into the surface of the coin. Any clean up would likely be temporary, but it would be interesting to hear from @Auricsstash about it (if he still has those specific coins that he washed). I imagine cleaning with Ammonia Hydroxide will be temporary as well, but maybe there's a chemical reaction that draws the staining out...who knows!

[TutoredSoup232]

I decided to sacrifice a milk spotted 2020 year of the rat coin to science. A good rub with Goddard silver polish did nothing. However it shined the coin up nice. Then I put soap and warm water on it to get the polish off and dried it with a polishing cloth. No more milk spots on my coin

However I now need a way to remove tiny scratches 😅

 

[sovereignsteve]

4 hours ago, Liam84 said:

I imagine cleaning with Ammonia Hydroxide will be temporary as well

If ammonia does work I would guess it will be permanent as it should remove the precursor as well as the milk.

[stefffana]

I am sure that @BackyardBullion know exactly how to clean his milky coins. Some high temperature and the milk spots are gone forever. 😄

 

[Arganto]

7 hours ago, TutoredSoup232 said:

I decided to sacrifice a milk spotted 2020 year of the rat coin to science. A good rub with Goddard silver polish did nothing. However it shined the coin up nice. Then I put soap and warm water on it to get the polish off and dried it with a polishing cloth. No more milk spots on my coin

However I now need a way to remove tiny scratches 😅

 

That's interesting. Was it dish soap? I wonder if using a lot of soap and just bare fingers/nitrile gloves would offset the scratching, as light pressure would keep a layer of soap between the finger and coin so not be as abrasive. Odd that's worked though! Well done 

[TutoredSoup232]

14 minutes ago, Liam84 said:

That's interesting. Was it dish soap? I wonder if using a lot of soap and just bare fingers/nitrile gloves would offset the scratching, as light pressure would keep a layer of soap between the finger and coin so not be as abrasive. Odd that's worked though! Well done 

Thanks, the scratching came from trying to polish it i think. Probably would've worked better if I'd just used soap and water. I used handsoap for mine. I was going to use dish soap but i was upstairs and the kitchen seemed so far away....

[Arganto]

Well, that's the order I'm trying then. I'll get the worst coin out and use hand soap first, dish soap if that doesn't work then the ammonia when I get it delivered. Nice one

[DarkChameleon]

Anyone tried boiling their coin?

[Pete]

As this topic has resurrected all I can share is that there is no chemical rinse suited for silver that will remove milk spots.
I have pretty much tried them all on sacrificial coins.
The only method that works is to mechanically polish and the end result will likely introduce fine lines but looking better than milk stained and spotted.
I have successfully polished fine lines out using jeweller's rouge but many coins have a satin-like finish which is affected by polishing so not every coin is suitable for polishing.

[Arganto]

Have you tried the Ammonia Hydroxide specifically @Pete? I've seen a promising video online, but then it's the internet which isn't always shackled to reality 😁

[Danny-boy]

I always used to use Hagerty Jewellery Wipes for my milk spotted coins.

https://www.amazon.co.uk/Hagerty-Jewellery-Wipes-Perfect-Sparkling/dp/B004FE6UUG/ref=asc_df_B004FE6UUG/?tag=googshopuk-21&linkCode=df0&hvadid=427946992514&hvpos=&hvnetw=g&hvrand=14954898377958081493&hvpone=&hvptwo=&hvqmt=&hvdev=c&hvdvcmdl=&hvlocint=&hvlocphy=1006969&hvtargid=pla-905928126682&psc=1&tag=&ref=&adgrpid=99265823403&hvpone=&hvptwo=&hvadid=427946992514&hvpos=&hvnetw=g&hvrand=14954898377958081493&hvqmt=&hvdev=c&hvdvcmdl=&hvlocint=&hvlocphy=1006969&hvtargid=pla-905928126682

Removed milk spots with ease, and I couldn't see any scratches with my loupe.

[stefffana]

1 hour ago, DarkChameleon said:

Anyone tried boiling their coin?

Nope. But... I can't see why not. Maybe it is a good idea.

[Arganto]

Thus far tried the hand soap; didn't do anything (the ingredients will be so variable for liquid soaps it would be difficult to determine if one is better than another). Also tried a pencil eraser on a small patch, this served to do nothing more than introduce small scratches and hazing. I did a bicarb and hot water bath over foil which removed the hazing left by the eraser and actually faded the milk 'spot' but I didn't expect this to do anything.

I'm considering trying a dab of posh car polish on a spectacle cleaning cloth for poops and giggles. It's not designed for application to metal but it is designed to remove minor marks/hazing/scratches in what is in reality quite delicate paint (auto paint sucks these days) so may do something. The milking on one or two these coins is the worst I've ever seen so tempted to just try for the sake of it.

I'll order the ammonia hydroxide (original plan) and some jewellers cloths (last resort that will at least pull the staining off) tonight or tomorrow.

Its likely the old hands are having a chuckle as these paths have been trodden by many over the years, and milking is still public enemy no.1 at large...you never know though! If I ever sell these coins I don't think the value will be any different all milky as they are or cleaned up with hairline scratches anyway 🤣

[stefffana]

25 minutes ago, Liam84 said:

Thus far tried the hand soap; didn't do anything (the ingredients will be so variable for liquid soaps it would be difficult to determine if one is better than another). Also tried a pencil eraser on a small patch, this served to do nothing more than introduce small scratches and hazing. I did a bicarb and hot water bath over foil which removed the hazing left by the eraser and actually faded the milk 'spot' but I didn't expect this to do anything.

I'm considering trying a dab of posh car polish on a spectacle cleaning cloth for poops and giggles. It's not designed for application to metal but it is designed to remove minor marks/hazing/scratches in what is in reality quite delicate paint (auto paint sucks these days) so may do something. The milking on one or two these coins is the worst I've ever seen so tempted to just try for the sake of it.

I'll order the ammonia hydroxide (original plan) and some jewellers cloths (last resort that will at least pull the staining off) tonight or tomorrow.

Its likely the old hands are having a chuckle as these paths have been trodden by many over the years, and milking is still public enemy no.1 at large...you never know though! If I ever sell these coins I don't think the value will be any different all milky as they are or cleaned up with hairline scratches anyway 🤣

If you are doing home made scientific experiments, try first alcohol, vinegar, lighter petrol... Who knows, maybe the result will be surprising.

[SilverJacks]

I have the quite aptly named "Knockout" household ammonia. Not sure if that's the stuff you're referring to. It absolutely stinks so strong that I assume it is dangerous. I'll try it on a milky Maple and post pictures tomorrow evening.

[TutoredSoup232]

1 minute ago, SilverJacks said:

I have the quite aptly named "Knockout" household ammonia. Not sure if that's the stuff you're referring to. It absolutely stinks so strong that I assume it is dangerous. I'll try it on a milky Maple and post pictures tomorrow evening.

Whatever you do, don't mix it with bleach!

[SilverJacks]

Duly noted. What happened? Did it explode?