Distilled water soaks work!

In clean environments, such as wafer fabs or optics manufacturing, distilled water (or de-ionized water) is used for cleaning and surface etching. Very clean DI or distilled water has etching properties that are inhibited by ionic contaminants. However, this is somewhat moot since the coins in these experiments are quite dirty, and even if distilled water is used, it will be quickly contaminated by the materials it is dissolving from the surface of the coin.

Keep in mind though that tap water today contains chloramine (a mix of chlorine and ammonia) and this mixture is chemically reactive. So if you are OK with rinsing your coins in chlorine and ammonia, then go ahead and use tap water. If those chemicals give you pause (which they do me) then I would suggest sticking with distilled.

 

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Whoa...let's talk about water. Really good stuff particularly with some added bourbon . Distilled water (evaporation followed by condensation) gives what we would consider pure water, 99.99999% except that there might still be organic solvents that distilled over with the water. Now tap water by government standards can contain 500 mg/L which would be roughly 99.95% pure (except in Flint, Michigan...not so funny). I have no idea what dissolved "rock" is. Also, chloramine is no more a mix of chlorine and ammonia than sodium chloride (table salt) is a mix of chlorine and sodium!
With that being said, soaking coins in water is a good thing. In most parts of the world, tap water is perfectly acceptable, however a couple of rinses with distilled water after the soaking is a really good idea. If you don't have distilled water, just make sure you blot the coins off after soaking.
@Seattlite86 I hope that orange color isn't rust.

 

If using acetone, how long should it sit if there is gunk on copper?

Does it literally melt off the gunk, or do you use a Q-tip or something?

And what do you do immediately after you take it out of the acetone bath? Let it dry? Rinse it? If so, with what?

 

https://www.epa.gov/dwreginfo/chloramines-drinking-water

 

"Formed by mixing" is not the same as "a mixture of".

Water is "formed by mixing" (and igniting) hydrogen and oxygen, but it's not "a mixture of" hydrogen and oxygen. Otherwise, it would explode when you poured it on a fire.

 

You quote "formed by mixing" but where did you see that stated? Here is an actual quote from the EPA website I linked to:

Chloramines "Are most commonly formed when ammonia is added to chlorine to treat drinking water."

 

The very line you quoted: "...formed when ammonia is added to [mixed with] chlorine..."

When ammonia and chlorine are mixed in water, they react with one another, and one of the products of that reaction is chloramine. Depending on conditions, they can produce a lot of other things, some highly toxic, some explosive; water treatment plants avoid those conditions.

But mostly that was just my inner pedant slipping out while I was sleepy and lacking self-control.

 

Not all municipalities use chloramines. Some do but I believe most do not. They require a special filter on an RO unit to remove.

Ok, just read above post. I'm learning here too. I honestly was aware of it but didn't know wth they were.

 

Thanks so much

 

First of 3 filters at the 10 micron level. These filter from the inside out so the brown on the outside is what made it through. Depending on where your municipality gets it's water it may have been sitting in rock for thousands if not millions of years. Do you think limestone won't dissolve into water in time?

I guess the point everyone's trying to make is that tap water is extremely contaminated with various things to be considered safe for cleaning a good coin. It's good for washing cars...if you have a spot free rinse available. lol

 

Limestone is calcium carbonate, also in different crystalline forms known as marble and as chalk. It has very limited solubility in water but small particles can be carried along in a stream of water. The difference in being dissolved and not being dissolved is filtration. You can't filter table salt (sodium chloride, a compound, not a mixture of sodium and chlorine, but their product) from water.

And finally on chloramines, let me quote my government source... https://www.cdc.gov/healthywater/drinking/public/chloramine-disinfection.html

 

So what is your take-away from the CDC that is different from the EPA?

 

My take-way is they say chloramines are used for disinfection rather than saying that chlorine and ammonia are added separately in the hopes that they make the correct chemical.

 

Well, they are added separately, but not "in hopes that they make the correct chemical" -- more like "in such a way that they make the correct chemical".

It's kind of like the way gasoline and air are added to a car engine, but what comes out the tailpipe isn't "a mix of gasoline and air".

 

Keep in mind though that chloramine is chemically active, and kills bacteria, etc through chemical reaction. I have never done an experiment to see what chloramine does to copper or silver but for sure it won't be "nothing".

 

Plenty of things are chemically active and kill bacteria but won't touch silver or copper. Hydrogen peroxide comes to mind. So does alcohol.

 

Are you sure? If that were the case, then it would be much safer to clean our coins with alcohol than with acetone, yet no one recommends using alcohol. Why is that? I'd bet it has undesirable effects. I'm not sure about hydrogen peroxide, but I'd bet it also would have undesirable effects, though it also would not be as effective at cleaning.