I recently bought some raw uncertified Morgan dollars from a dealer. I noticed after a few weeks some dark areas have started to develop on the coins. I noticed one time I was in the coin store the dealer had treated an uncirculated coin that had pvc on it and had rinsed it off with tap water and dried off the coin by patting it with a paper towel. Since tap water can contain high levels of salt can rinsing off a coin with tap water cause any corrosion on the coin? Can the flouride in tap water also affect coins? I suspect that my coins may have been treated before I had bought them. Would I cause further harm to the coins if I rinsed them off with distilled water to rinse off any salt? Also, is there anything in the paper towel that would be bad for coins?
Tap water can have lots of minerals. Our tap water at my house has that rotten-egg sulfur smell (those of you who've been places in Florida might be familiar with it). Paper towels also have a good bit of sulfur. Sulfur is used to tone silver coins- sometimes attractively- often not- but the sulfur in paper towels and napkins really should only affect a coin if it's left wrapped up in the paper longterm. Otherwise, paper towels are fine to use. Distilled water is best to rinse a dip off with. It's more likely the coins you are speaking of had residue of the dealer's dip solution left on them, or traces of the PVC contamination (which can be beastly to treat, from what I've heard).
Your post brought to mind something that I think happens rather often. That being that when someone is a coin dealer people seem to automatically assume they (the dealer) know what they are doing. Well, sometimes that is the case, but far more often it is not. Coin dealers are no different than any other group of people, sometimes they know what they are doing and other times they don't. Or they can be quite good at one aspect of their business and yet terribly bad at another. Think of any trade you care to think of, doctors, lawyers, plumbers, electricians, painters, the list goes on and on. Some are really good at their jobs, but most are not. Some are not even adequate. So just because you see a dealer doing something or a dealer tells you this or that - that doesn't necessarily mean he's right ! And remember, he may be Aces in one aspect, say grading just as an example, but absolutely terrible in another aspect like say authentication as an example. And it doesn't much matter what you read or hear either, feedback or recommendation is only as good as the person giving it. I guess what I'm trying to say is you need to get know coin dealers, really get to know them, before you afford them too much of a degree of trust. Just like you do with any other person in your life. As to your questions, yes tap water is bad. Yes paper towels are bad. Tap water is full of all kinds of things that may be harmful to your coins. Paper towels are abrasive, as are all paper products. Granted, if you're talking about a well circulated coin and you wash it of in tap water and blot it dry with a paper towel - you're probably not going to hurt it any more than it already has been. But, if it's a BU coin, or a coin actually worth something - well, it may not be for very long if you treat it that way. And yeah, I know, it's written in books and dozens of articles and on hundreds of websites to "blot" your coins dry after washing/rinsing them in distilled water. But that doesn't mean it's a good idea. It's found in all those places because what everybody does is to merely copy what somebody else said. And that's where all the bad information found in books and articles and websites comes from. And believe me there is just a ton of bad information out there. And yet it just keeps on getting repeated over and over and over again because everybody figures - hey, they all said it, they can't all be wrong ! But yes, they can !
Disclaimer: Doug brings up a good point. I should clarify that when I said paper towels are otherwise "fine to use" above, I meant to lay the coin on for drying, short-term. Not leaving it wrapped in a paper towel or rubbing it.
I use warm running tap water to rinse my coins after I dip them then place them on folded soft toilet paper and pat dry. I have done this with coins from low value to high hundreds. Regular strike to proofs to PL & DMPL. Never had a single problem. The trick is to pat dry right away and completely before any minerals from the tap deposit on the coin due to natural evaporation. If I have distilled water at hand I'll do a final quick rinse with it especially on high value coins just as an extra measure but it's not a necessity
Be careful, too many areas don't have great tap water. This is dangerous in many areas of the US. I've lived in Mich, NY, Ohio PA. and Florida. and all of these areas I wouldn't put any of the tap water on my coins. I've lived in many areas and there is a lot of minerals, sulfer and calcium.. etc.etc. If you really like your coins don't clean them unless your trained. I won't buy a coin labeled as improperly cleaned. The minerals will stain my pool if I don't treat it. The calcium will leave lines on my tile and hard water deposits on my glass shower doors.
Sounds like a sign of dip being used and not being rinsed off well enough or better yet neutralized. I would also never use tap water as a gallon jug of distilled water is like a dollar, so why risk it as you never know what concentration of what is in that tap water.
The pressure of the water from the tap is what helps. Rinsing the coin fully after a minute or so of flipping it in your fingers. I too have a high mineral content in my water. Doesn't effect the coin one bit of you pat dry it quickly and completely. I do agree though that you must know what you're doing to do anything more than giving a coin an acetone bath. I taught myself on ikes and now I'll do it to very expensive coins that I think would benefit from it. But I am confident in my ability. Its always a risk however.
The chemicals found in the tap water, unless you are sipping fresh swamp water are in solution and stay there. You can test this by putting a cover on a glass of tap water and let it set for days. Any sediment should be reported to the water district as your pipes and theirs are probably becoming blocked. The salts in tap water are ionized and are not able to physically damage the coin for a short period of time unless they evaporate on the coin. Leaving distilled water to evaporate on coin ~~Not as bad Leaving tap water to evaporate on coin ~~Bad, Rinsing with distilled water or tap water and blotting with anything ~~Very bad Rinsing with distilled water and then acetone and held on edge to air dry~~Good ( unless of other material than the standard coin metals).
Never, ever had a problem even with DMPL coins and all have straight graded. Blotting or patting in between soft toilet paper is perfectly fine you just don't want to wipe across the coin.
I've been distilling water for several years for my sleep apnea unit's humidifier and for use in the whole house humidifier. In the large humidifier, in the spring when we put it away for the summer, there is virtually NO mineral buildup. I can use the filter medium for several years without replacing it. Years ago when I used tap water the humidifier and filter would be a crusty mess. To meet our needs for distilled water I use a distiller that cost me just over $100. Even with the electricity, I probably pay only 35 cents per gallon. To test the effectiveness, I distilled a gallon of water, cleaned the distiller, distilled that gallon again, and found, to my pleasant surprise, that there was no discernible mineral crud left in the distiller. That double-distilled water is what I use to rinse coins. Even if I had to pay a dollar a gallon I would still avoid tap water. An aside: I am in Norway several weeks/months each year. When I tried buying distilled water there a few years ago it was impossible to find in a city of 3,000. Most retailers had no idea what I wanted. I finally had to buy medical grade purified water at a pharmacy at outrageous cost. Although I wanted it for my apnea machine, if it had been for rinsing coins I would've been tempted to head for the tap. Steve
The problem with patting a coin dry, with anything, is it's too easy to get slight movements and hairline the the coin. Yeah you can be lucky and not have it happen, but you can be unlucky and do have it happen too ! Also, paper towels or napkins, regular towels, any kind of cloth, they can all leave small (and I'm defining small as pieces you're not likely to see) pieces of cloth or paper on the coin. And later, those will cause toning spots. And probably before you notice it. Now, if you use distilled water to rinse a coin, then just stand the coin edge on a soft towel with it leaning up against the backsplash and let it dry. Any excess water will run off and into the towel, and any traces on the coin will just dry with no harm done. This completely removes the issues of potential harm from patting or blotting dry.
Any time you superheat a pure liquid ( not a mixture) and there are no nucleation points ( such as would be ions in tap or natural water), any disturbance can cause gas bubbles to form so suddenly, the water and steam blows out. But if you add anything like powdered soup or tea before starting, it will just boil over and not explode.
I would not recommend this, you have to be very careful of all the Sulphur in the paper towels and the tap water can leave mineral stains. Also paper products are highly abrasive would highly recommend only using a little bit of distilled water if you must rinse your coins. ED
Paper products (towels) contain wood fibers which can scratch the surface of a coin. For pointers on rinsing coins search this site for advice on coin cleaning. You will find very good instruction from GDJMSP.
Try this: take a quarter from your pocket change (a quarter worth no more than face value). Examine the surface carefully, paying very close attention to any hairlines. Even better, take a quick photograph of it. Now rinse it with tap water. Gently pat or blot it dry with a paper towel. Examine it again very closely. Unless you vigorously rubbed that coin with that paper towel, I'll bet you won't see any hairlines.
As I said, you might not - And then, there's this. No guarantee it will happen of course, but it absolutely can. The point is, is it not better to avoid those possibilities when you can easily do so ?
