Preservation of Lincoln cents

Glass is usually not the outermost surface of a lens. The outer surface of most, and especially very prestigious and expensive lens is a thin film rare earth mixture which is much softer than glass. These layers are usually 2-5 millionth of an inch thick and if a gold coin was rubbed against the lens surface, I am sure the lens surface would lose.

Jim

 

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Only talc and gypsum are softer than gold. So I doubt very seriously that any mineral (rare earth mixture) would not scratch gold. Here is the Moh's hardness scale. Note the position of a fingernail. That is carotene which is the same material as hair.

Hardness Substance or Mineral
1 Talc
2 Gypsum
2.5 fingernail
2.5 to 3 pure gold, silver, aluminium
3 Calcite, copper penny
4 Fluorite
4 to 4.5 Platinum
4 to 5 Iron
5 Apatite
6 Orthoclase
6 Titanium
6.5 Iron pyrite
6 to 7 Glass, Vitreous pure silica
7 Quartz
7 to 7.5 Garnet
7 to 8 Hardened steel
8 Topaz

 

Ok, I agree ~ don't use a brush on pure (99.99) gold coins as the Vickers Hardness scale for pure gold is 20-25 Vickers and Keratin is 10-25 ( depending on the helix junctions to make fingernails or hair), so it is possible for the high end of keratin ( like a fingernail ) to scratch a Kugerand.

However, for coinage gold of 90%, about 22 kt. has a vickers hardness of 75-80, higher than the keratin range. Coinage silver is higher also.

The Mohs system of hardness was based on comparative hardness, what can visually scratch what. It certainly wasn't intended to deal with 4 millionths of an inch thickness.

Hair with its cylindrical hollow structure and looser binding molecules allow more flexibility and doesn't have the "scratch" potential unless it is molecularly glued together as is the keratin in fingernails. If you ground hair against gold like a cloth, then it is very possible to scratch.

With common sense, the use of a sable brush against your skin would not produce a scratch, use a fingernail clipping and blood may flow. We know that "cabinet rub " occurs from coins moving on lining made of plant fibers like cotton, yet people still recommend using cotton gloves to handle coins. We wouldn't recommend rubbing th e coins with the cotton gloves.

I don't use a brush...just don't see a problem if others want to use it.

Jim

 

It came from Wiki so I don't guarantee it it dead on, but I know enough to tell you any error is minute.

BTW, a fingernail is to a brush (any hair you want) as pig iron is to steel wool. The size of the hair does not affect whether or not it will scratch - although the thickness of the hair does affect the force you can generate to cause the scratch.

Despite all these "facts", I would still like someone to show me a coin that has been scratched by any descent brush. If it exists, the picture to show the scratches would have to be taken with an electron microscope.

 

blow off the dust and preserve (accidental unhappy face- how do I remove?)

Bill here are my humble thoughts on the subject: I agree with the bulb for blowing off dust, though have not done it myself. If you bought any of those coins I would get the dust off because those coins will be harmed with time. Pure acetone should also remove the dust and will usually remove some other types of damage (leave small amount in glass dish, let evaporate to see if residue; if so, then it is not pure and will change colors of coin) . I use "Coin Care" which is an oil based/solvent product which I dab (no rubbing) with a microfiber cloth. Also have used pure mineral oil which may be better. Never had any problem and coins are preserved. I have looked under 20x magnification before and after process with no damage (removed with acetone several times to see if any hairlines). Maybe visible under many times magnification- 50+??? but who cares. If anyone is looking at a coin with greater than 20+ magnification they should get a life!!! The damage from carboard dust is much worse than this speculative invisible damage. This is basic chemistry. All elements in oil based products have a strong and equal attraction toward each other which cannot be broken except by a solvent. Metals by their chemical nature are reactive with ionic compounds like sulfer or pollutants in the environment. These contaminants will not get past the oil barrier on the coin as they are not strong enough to break those covalent bonds within the oil. People who say NEVER CLEAN A COIN are grossly over generalizing. Do a search on "Cleaning" and "verdigris" on this forum and you will find further evidence of what I am saying and others arguements against PRESERVATION are quite weak and unscientific. Besides look at the NCS website and see before and after coins which get graded by NGC and you'll see that the never clean the coin group simply lacks the knowledge or skill to preserve their coins in the appropriate way. NCS has the ultimate "secret" techniques which none of us peon's seem to know what those are. Ultimately humidity has to be controlled which I have finally achieved with a ridiculous # of dessicants and room a/c. Sorry to get so opinionated or to offend "the other side" but I feel very strongly about this, because without preservation the overall supply of nice coins will dwindle over time due to environmental damage.

 

If you mess with coins, they get worse in most cases. I have no problem with a little coin care and a rose thorn or toothpic to remove the goober or the kling-on ( tribute to Spock ) , acetone for the PVC, etc.

Nobody like coins with an obviously removable hunk of goo or gunk.

When you get into trying to remove spots ( you cant) , improving color ( you'll ruin it ), or similar " doctoring " ( no matter how much care you use ) you will damage the coin.

Best policy? Avoid them in the first place. Don't buy them. Pass at those " discounted problems". They are always problems, and when you go to sell, you'll be looking for a fool to buy them. The bigger fool theory.

There is no price too cheap for a problem coin.

Edit: paragraphs make things easier to read

 

I completely agree. if you buy problem coins you are asking for it. it doesnt matter what your justification is.

 

I will ammend some of my above statements in that recently I have discovered that Coin Care (and probably Blue Ribbon which I just got, so for me the jury is out) leave a residue with time. I think because the solution is more aqueous it seems to evaporate. I noticed this on a few lincolns I put it on after about 6 months time. I would advocate mineral oil based on more reading and good preservation noticed after a couple years time (no negative changes noted). These are just my opinions. Some may argue acetone the coin and put in proper storage (which I do too) and coins will be fine. Which may be fine too. Ultimately we should all practice on worthless common, modern coins. We should never do anything harm to our valuable coins without proper experience. I scratched a VF 1915 D Lincolns with a toothpick due to inexperience. I now use a rosethorn with magnification and I am quite good at it. Totally confident I would not scratch any coin now after a lot of practice on low value coins of late. This of course will not remove verdigris. I am currently use hydrogen peroxide (a basic alkaline solution) to remove verdigris with very good results. I will post photos when I finish.