xylene substitute

Here is one; http://www.stonybrook.edu/vescalab/research/research7.html

Sorry, but I cannot find the one posted here, but it really does.

 

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That's... astonishing.

I've googled around a bit, and I don't see a lot of support for this outside of the original reporter. It seems like this would be a Really Big Deal, if acetone is recommended as an industry-standard degreaser for copper. But I certainly don't have grounds to dismiss it out of hand.

(BTW, the reaction they propose isn't actually oxidizing acetone, not that that makes any difference for this discussion.)

Thanks for the link! I suppose at this point I'm solidly in the "no acetone on copper" camp, at least until I get a darkroom set up.

 

That's the idea, assuming it didn't contain any dissolved residue to begin with, and didn't dissolve anything off of other areas of the coin.

 

There is another link I posted on cointalk which gives a different reaction that, I believe, is just with oxygen. However, the search function says I have only posted the word acetone twice since I joined and one of them is not this thread. Somehow, I think it is missing more than one entry. From what I can remember, neither of these reactions are anything that happen overnight, They take time - lots of it.

 

People don't generally leave a container of acetone open and exposed "water vapor". I really wouldn't be concerned unless the container was stored improperly or the acetone was impure.

 

I hate to say apples and oranges, but lets be sure. My thought is that the original concern was safety in use and possible resulting illnesses and physiological changes. And perhaps the substitute for xylene is somewhat safer, we only have limited evidence to consult, and most is from the manufacturer and seller.

This product was designed not to be a substitute for xylene on metal surfaces ( such as coins), but to be a chemical for removing lipids from microscopic slide when processing them for histological stains ( almost all stains are water soluble and hard/impossible to penetrate lipids and cell membranes (that are protein-lipid nature). I couldn't find another usage of the product on the manufacturers site. But I would guess if one followed the directions of use, extrapolating for metal rather than tissue, one's health would be better, however they indicate that this substitute is affected by water more than xylene in tissue preparation and doesn't react exactly the same, as a histology tech has to use their special adhesive to attach the cover slip rather than the traditional medias.

It will be interesting to see how the material works on metals, I suspect OK.

Jim

 

I will let everyone know after I try it next week. All I know now is that I need a substitute for the copper/bronze medals and coins. The only way to find out is by trying.

 

If recollection serves me correctly, this other reaction was taking place when the coin was left overnight in an open (unsealed) petri dish.

 

Well, maybe you come across photocatalyzed metathesis reactions between water and simple ketones on a frequent basis, but it was certainly news to me.

(I was agnostic about acetone damage to copper, but the particular chemistry in the linked article completely blindsided me.)

 

I do not feel that the abstract quoted above spells out all of the details of this experiment. Here is an illustration of the setup and since I don't wish to spend the money to buy the article, I will say that I have never used acetone on a coin anywhere close to this situation. He has sure nursed this theory as it has appeared in many citations , but no one has bothered to confirm or defeat. in a previous version, he used salt water, and perhaps here also.

http://www.sciencedirect.com/science/article/pii/S0013468601003590
I know Doug's thinking about acetone and copper, and although I certainly couldn't disprove his hypothesis, I do not feel this experiment confirms it , IMO.

Jim

 

I'd like to see the full paper, the little tidbits on the web don't tell us much of anything. However, I did google the first author, he looks to be legit and has done a lot of publishing.

 

Like I said, I don't know enough to dismiss the claims out of hand, but I am a little puzzled that they aren't more widely cited. All the abstracts and summaries include the bit about "use of acetone for degreasing copper and copper containing alloys as recommended by ASTM E1078-97". If this is really a widely-applied standard for cleaning copper, and this researcher really has shown that it can result in significant corrosion, why in the last 12 years hasn't it been more widely discussed?

Sometimes it does take a long time for legitimate discoveries to be widely accepted (see, for example, Helicobacter pylori and ulcers). But sometimes, claims are just wrong.

Of course, even if this particular claim is completely baseless, it doesn't prove that acetone is safe for copper coins.

Maybe next weekend I'll run an experiment or two. Should be easy enough to set up the light-vs.-dark comparison, put a microscope on the light-vs.-dark coins, and maybe even stick some litmus paper in the light-vs.-dark acetone.

 

You have completely convinced one person myself. I have seen the reaction for myself, and reading responses on this forum confirms it. That is why I want a substitute solvent for copper and bronze.

 

Come on Doug, the fault is with a poor quality of acetone, it's NOT acetone itself. If someone keeps acetone on their shelf for 10 years and uses it still, it's NOT the fault of the acetone. I have used pure, reagent grade acetone on copper for YEARS and I have NEVER seen ill-effect. I rinse every single one of my Lincolns with acetone before storing in an airtite or other holder. I'll stand my claim that chemically pure acetone will have zero negative effects to copper because it's scientific fact.

 

On the other hand, most people are going to have access to hardware-store acetone, not reagent-grade. If there are dangerous impurities prevalent in commercial-grade acetone, people need to beware.

BadThad, what would happen to acetone on the shelf? Would it react slowly with CO2 and water from the environment? Or would it peroxidize? (I don't think I've heard of ketones doing that, just ethers...?)

 

I will agree with this, but will add the caveat that it be used properly.

 

I've known about that abstract for some time. But frankly I don't soak my copper coins in acetone for 18 hours. Typically I might swish them in the acetone for five seconds or so. So if it DID grow those crystals they would be about .007% the size of those. The ones in the abstract look to be less than .5 mm so the crystals I would get would be about .00004 mm or in inches .000002 or about 2 millionths of an inch. Maybe I should get a scanning electron microscope and see if I can find them.

How long would there still BE acetone in that open petri dish left sitting out? I think during most of that overnight the coins was just left exposed to the ambient atmosphere.