What is this brownish stuff?

CRHer700

I keep many coins that I have CRHed in stacks on my shelf, and I have noticed that over time, some coins have developed a reddish-brown haze on them. Below are the specific details of the coins with the stuff on them.

1. Only silver coins, no copper or nickel.
2. Only the side facing up receives it.
3. It isn’t the shelf itself, as coins at the top of stacks get it.
4. Only occurs on coins not covered by another coin.
5. The stuff wipes off if you run a piece of fabric over the coin, but sticks in recessed places on the coin.

Here are pictures of some affected rosies, the reverse of the 1952( facing down on the shelf) is shown to illustrate the difference in color.





As far as I can tell it must come from the air and settle straight down onto the coin based on which parts are affected. Any opinions on what it is, where it comes from, and what to do about it are welcome.

PeakRarities

The merc looks like it was stored in an envelope and there was moisture. I see that look on a lot of early silver and I’m not a big fan of it.

hummingbird_coins

@PeakRarities said:
The merc looks like it was stored in an envelope and there was moisture. I see that look on a lot of early silver and I’m not a big fan of it.

I think these are developing on his coins as they are sitting on the shelf.

CRHer700

@PeakRarities said:
The merc looks like it was stored in an envelope and there was moisture. I see that look on a lot of early silver and I’m not a big fan of it.

That's odd though, as I pulled it from the coin star and it was already dark, but this brownish substance was added later, and it has never been in an envelope.

coinbuf

Just residue that is reacting with the environment you live in, is it dusty, humid, combination of those? As these are circulated coins unless you washed each coin in acetone there is bound to be some skin oils on the coins, those oils or other surface contaminates will change the surface over time as well as attract dust.

CRHer700

@coinbuf said:
Just residue that is reacting with the environment you live in, is it dusty, humid, combination of those? As these are circulated coins unless you washed each coin in acetone there is bound to be some skin oils on the coins, those oils or other surface contaminates will change the surface over time as well as attract dust.

They are in the air conditioning, but I live in a very humid area. I wonder if that speeds it up.

PeakRarities

@CRHer700 said:

@coinbuf said:
Just residue that is reacting with the environment you live in, is it dusty, humid, combination of those? As these are circulated coins unless you washed each coin in acetone there is bound to be some skin oils on the coins, those oils or other surface contaminates will change the surface over time as well as attract dust.

They are in the air conditioning, but I live in a very humid area. I wonder if that speeds it up.

Air conditioning removes humidity, so if the AC is running strong then I doubt it. So you know what the RH (relative humidity) is inside your house?

CRHer700

@PeakRarities said:

@CRHer700 said:

@coinbuf said:
Just residue that is reacting with the environment you live in, is it dusty, humid, combination of those? As these are circulated coins unless you washed each coin in acetone there is bound to be some skin oils on the coins, those oils or other surface contaminates will change the surface over time as well as attract dust.

They are in the air conditioning, but I live in a very humid area. I wonder if that speeds it up.

Air conditioning removes humidity, so if the AC is running strong then I doubt it. So you know what the RH (relative humidity) is inside your house?

Nope. I might be able to find out though.

Bikergeek

An observation I made (in my cool air conditioned house in humid Kansas City) today: I had a glass of ice water and very quickly, big drops of water coated the entire glass and dripped down onto the coaster. It's not scientific, but if you do the ice water test in the room where you keep your coins and it's instantly soaked, you can bet that humidity is working on your silver. ;-)

Coinscratch

Do you live close to a chemical plant?

PerryHall

Are there any smokers in your house? I remember in the old days coin dealers would take a dipped cent and blow cigar smoke on it to darken it and give it a more natural appearance. Not sure if they still do this.

PeakRarities

@CRHer700 said:

@PeakRarities said:

@CRHer700 said:

@coinbuf said:
Just residue that is reacting with the environment you live in, is it dusty, humid, combination of those? As these are circulated coins unless you washed each coin in acetone there is bound to be some skin oils on the coins, those oils or other surface contaminates will change the surface over time as well as attract dust.

They are in the air conditioning, but I live in a very humid area. I wonder if that speeds it up.

Air conditioning removes humidity, so if the AC is running strong then I doubt it. So you know what the RH (relative humidity) is inside your house?

Nope. I might be able to find out though.

Anything above 60% might be cause to experiment with alternate storage solutions. In my safe, and safety deposit box, I use dessicant packs to help wick up the moisture. I would buy this and put it where you store your coins, just to be sure.

https://www.amazon.com/ThermoPro-TP50-Digital-Thermometer-Temperature/dp/B01H1R0K68/ref=sr_1_1_sspa?crid=3CSOEIIA6X37N&dib=eyJ2IjoiMSJ9.oKbRZRMgkFkS2IsXGJHokY9V_M8Wn6OMI3ieTIDdEG3GpUwbisfBZKmX3fk6poM5p2RWaYCtl4wIBZWhheaJssgcYgoL6Mhg3Tyblm3IE3CBe19luSTdESBwoFePRP7jWUfbTxbR4CYllowNKuarCNTn0Y4dTUOqfuv1RcyF_tCChvPFsCHonJKARFwCiS8hQLtax9bwsEJsl7I8w1fXqCRC5OVXybmoQ_qHR24KX5Tp55fMnMVWZwP3pTFxVE_133LjkJHOI4aNGNt_dO7w-gn3cg7aeCLwdrxiMt0hQxw.7mCdVpa6wCYRwXh80_igmg8cWF5hq6lzVPz4DXou1-s&dib_tag=se&keywords=humidity+meter&qid=1725211499&s=hpc&sprefix=humidity+,hpc,626&sr=1-1-spons&sp_csd=d2lkZ2V0TmFtZT1zcF9hdGY&psc=1

CRHer700

@Coinscratch said:
Do you live close to a chemical plant?

No.

@PerryHall said:
Are there any smokers in your house? I remember in the old days coin dealers would take a dipped cent and blow cigar smoke on it to darken it and give it a more natural appearance. Not sure if they still do this.

No.
I assume that it must be the humidity, but I don't get why it only affects silver and not copper or nickel.

CoinRaritiesOnline

Almost never a question I want to hear.

Cougar1978

Envelope or wallet tarnish.

joeykoins

Been frying alot of eggs recently?

oreville

Mercury dime looks like it was dipped then re-toned an ugly brownish color.

The roosevelt dime looks like a shadow from the finger? Hard to tell from photo.

Cougar1978

Perhaps the roll stored in hot garage for ages.

CRHer700

@oreville said:
Mercury dime looks like it was dipped then re-toned an ugly brownish color.

The roosevelt dime looks like a shadow from the finger? Hard to tell from photo.

I know my pictures are bad, but in real life the Rosies are the same color as the merc.

oreville

@CRHer700 said:

@oreville said:
Mercury dime looks like it was dipped then re-toned an ugly brownish color.

The roosevelt dime looks like a shadow from the finger? Hard to tell from photo.

I know my pictures are bad, but in real life the Rosies are the same color as the merc.

A tight one way rub from your clean thumb and forefinger should eliminate the ugly brown toning. That kind of toning occurs no matter how your dime is stored. The Roosevelt dime reverse side does not show the same brown toning.

CRHer700

@oreville said:

@CRHer700 said:

@oreville said:
Mercury dime looks like it was dipped then re-toned an ugly brownish color.

The roosevelt dime looks like a shadow from the finger? Hard to tell from photo.

I know my pictures are bad, but in real life the Rosies are the same color as the merc.

A tight one way rub from your clean thumb and forefinger should eliminate the ugly brown toning. That kind of toning occurs no matter how your dime is stored. The Roosevelt dime reverse side does not show the same brown toning.

You are correct, and that is what I will have to do.