Rose thorns and Oil

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First off, the results are quite nice, congrats. I too prefer not to have gunk in the devices.

Mineral oil should be removed with XYLENE. Oil is only slightly soluble in isopropanol. However, oil is completely miscible with xylene. It will remove all traces of the oil and do no harm to the copper surface. Acetone would also be a very poor choice for removing oil, it's far too polar and oil is practically insoluble in acetone.

Here's a good, scientific test for those of you that do not understand solubilities. Take a clear glass container (a test tube is best) and mix equal parts of oil and your choice of solvent, and mix well. If two layers form upon standing, it's not a good choice as a removal solvent.

I should also add that pure mineral oil is completely non-reactive with copper. However, only it's of extremely high grade. Most oils will contain other dissolved substances that could have non-polar characteristics. These could react and bond to the surface. While it may not be apparent in the short-term, there is a chance that over time, these impurities could alter the surface of the coin. This is the reason I do not recommend storing coins in mineral oil.

 

GD, I appreciate you doing those side by side photos. I will try and rephoto tonight with and without mineral oil. I want to be clear I don't submit all coins with oil. Just the ones I that are more porous. Doesn't look good on flat strikes as these are less porous and look reflective. Strong strikes have mor porosity in the coin and more prone to verdigris damage in my opinon.

 

Thad, thanks for the reply. It's funny you say that about xylene because I ran out of acetone and it's hard to find pure acetone. I have heard a lot about xylene and it's in every hardware store. The mineral oil I use its Johnson and Johnson. I have seen no ill efects over several years, but never had on coins 10-20 years (only been collecting for 2 years). Where can you buy high grade. It still think the potential impurities couldn't touch the damage potential air contaminants can do and therefore it's the safer of the two options for me.

 

You have to realize no chemical is 100% pure, no matter how hard you try to refine something, there will ALWAYS be impurities. Mineral oil is petroleum-based, perhaps one of the most difficult materials to purify....consider the starting material.

My biggest concern with oil is sulfur, it's probably the best solvent for dissolving elemental sulfur and I guarantee you, no matter how good the mineral oil is, it WILL contain trace amounts of sulfur. Sulfur is particularly good at discoloring a coins surface over time, depending on concentration. This is true even if oxygen is not present. It's not a matter of if, but when will it happen.

While your theory seems well founded....i.e. air vs oil, I will take my chances with air any day over oil. Airtite holders are very, very good. The seal is excellent and the permeability of the material is extremely low. The probability of seeing surface corrosion either form or continue while protected from air is virtually nil. Compounds like verdigris (sulfate and carbonate types) are highly dependant on two things to "grow", oxygen and water . Removal of those "feed" materials will stop verdigris and most any other type of corrosion.

Great discussion, thanks for the topic.

 

Thad- I had read several chemical anaylsis articles discussing the break down of oils and particularly oxidation and sulfur reactions with mineral oil. They stated reactions like this only occur with extrememly high temps. Also based my conclusion on Mr Whites book "Coin Chemistry where coins notedly toned in air-tites in acclerated sulfur environments. Kointain and NGC holders toned the least. The oil cuts off both air and water and that's why I feel they won't devlop verdigris or tone (trace sulfur may be bound to oils but it rendered inactive). The articles I read supported this idea. I will find and post later and maybe you could comment. Appreciate your feedback. I am open to the idea I could be wrong!

 

So what happens?

 

While I've never used these products, over the years I've read about them and studied whatever I could find on the web (I recall finding MSDS's). From what I reemember, they are mainly detergent-based and likely of a pH such that they will cause permanent damge to the coins surface. I would only use these harsh products as a "last ditch effort". I suspect they would also cause coins to tone oddly over time.

 

It's true that mineral oil is resistant to oxidation, much more so than veg based oils, which require antioxidant packages to remain stable under any condition. Sulfur will only covalently react with mineral oil under somewhat extreme conditions. The trace sulfur present in oil is NOT bound. It is DISSOLVED and free to react. All it requires is a surface to react with, regardless of temperature (temperature will only affect the rate).

I recall reading an article not long about about an accelerated test. However, the conditions (as I recall) were EXTREMELY severe. While as a scientist, I do not disagree with the basis of the methodology, as there's no other way to evaluate the effectiveness, I feel the test was not of the "real world". A careful and astute collector should be aware that something like an Airtite is not the final measure of protection, but one of many steps.

My long term storage procedure is very thorough and I believe my coins will last virtually forever. I rinse the coin with acetone to remove trace moisture and residual, soluble contaminants. The Airtite is blown out with canned air to remove particulate matter and the coin is sealed. The Airtite is placed into a 2x2 holder so I can write the date/mint/grade on it. That 2x2 is placed into a Cowen 2x2 plastic sheet and affixed to a 3-ring binder. The entire binder is then put into a giant ziplock bag with a huge dessicant pack or two. Then I take the whole bag to the bank for safe keeping in a deposit box.

I'd be willing to put my entire bag into any of accelerated conditions specified in their test....I'd also be willing to bet that my collection would suffer no ill effects.

 

Thanks Thad for the response. I will conceed to GD and any others I certainly cannot discredit ones personal observations of a given coin or coins over a long period of time. However, one could agrue that a coin that was believed to be "harmed" by oils- how certain are you that it was the oil? There are a lot of variables involved and of course oil will somewhat disolve over time. Not many of us do contolled experiments like Jim did so cause and effect analysis becomes tricky. I will say you have assisted me to cast possible doubt about leaving oil on coins in the long-term. I may revise my practice here. I will do some more reading on the subject. I do give credence to someone with a lot more experience than me (like GD) and weigh that into my decision-making re: storage methods. I do very similar storage methods as Thad. I use IS and Air-tites in an IS box and use ziplocks that suck out all the air with a little pump with dessicant inside. I wonder if Jim has any opinion on the discussion if anyone wants to PM him. I'm at work now.

 

Boss, sorry I was messing with a property management problem all afternoon and haven't been following the thread. I have never used oil on any coins. nor MS70, Blue Ribbon or anything like that as a preservative. I agree with Thad that oil has its own problems and as long as the coins are kept from circulating environmental air and moisture, no change in the surface should occur. A closed container such as an air-tite, or the hard plastic holders contain more air when closed than a Koin-tain shell, so as barometric pressure varies, the air can move in and out more readily. The Koin-tain has much less exchange with new environmental air. If they weren't so @#*% hard for my fingers to handle, open , close...I would use them more often. I think that tightness of seal is why White found them highly, but not ENTIRELY effective.

As you recall, I did a simple experiment with Ziplock vacuum bags and I really like those bags. I do find that a piece of tape over the valve increases their vacuum holding ability. Unfortunately they disappear rapidly into the kitchen. Walmart has a good price on them and the pumps. I still prefer to use a heat sealer and seal the mylar 2x2 flip after squeezing the air out as the coins are easier to organize for me

I use to build and maintain mechanical clocks as a hobby, and finding a clock oil that was light enough not to slow the gears, stable enough not to gunk up, and neutral enough not to corrode the brass parts took me years. I just have one small vial of it left. If I used an oil , it would have to have those properties, and my old supplier does have it anymore

I do like Spock,:goofer: but I can't agree with his theory that verdigris is almost an alive infection that can grow and spread on its own. It will only develop if there is moisture and corrosive agents like acids, sulfides,etc. and when this is removed, the verdigris will stop increasing. The coin I did in Verdigone experiment, when I finally rinse it with acetone or xylene and put it into a protective environment, I do not expect any increase in damage. The remaining corrosion can not increase without moisture and environmental factors in the air. It Won't disappear, but it won't grow either! That's my story and I am sticking with it!:hammer:

Jim

 

Indeed, verdigris is like a fire, it must be fed to continue to grow and survive. Unless you're God, you cannot create matter from nothing.

 

Well, boys- here's my conclusion. I think I will revise my long term oil policy and stick with it's use in only the short term. I think there has been enough doubt cast, at least for me that, I don't want to chance it. Combined with people's longtime experience compared to mine, I will trust that the potential what if is not worth it for me. I use all the methods I should to protect my coins, and will only use mineral oil for short periods to remove verdigris and gunk. Verdigone has worked really well as well (however, one must admit this is significantly more reactive than oil could ever be whether a coin is in for 5 minutes or 10 days- so you have to be careful and keep checking the coin). Thanks for everybody's input. I am always learning. I have to admit, I like how coins look with the oil though, but I will use on only a short term basis. My next post will be how to fix my lacquered coins. Can't get the dang lacquer off and the coins I did are all screwed up underneath so I am SCARED TO DO SO.:crying::crying:

 

As for your lacquered coins, you may be looking for heat - and that does not necessarily mean boiling hot especially with flammable solvents. As a rule of thumb, for every 10° Celsius you raise the temp, the reaction speed doubles and in the case of dissolving, I would not be surprised if it quadruples. If 20° is normal temp, 60° would at least 16 times as fast.

Caution - all solvent you are talking about become very volatile at those temps and acetone boils at 56° C. Xylene and toluene both boil above water and are probably better for lacquers.

However, nothing will help a damaged coin.

 

Boss, What kind of lacquer are you talking about?

Jim

 

I think you have removed the verdigris, but for those who know what to look for, the now-untoned areas around the letters looks unnatural. It would be interesting to see how the coin would be viewed by the TPGs if you sent it back in -- altered surfaces wouldn't surprise me. Respectfully...Mike

 

Good short answer, Doug. A while back in a different thread I gave him the long answer. Did everything there but draw him a diagram. Find that, here: http://www.cointalk.com/forum/t46252-3/#post501752. You live and learn.

 

Eddie- I never actually realized you replied or forgot to check that post for some reason. Thanks for the pics. That is very helpful to me.