There is much advice on CT to use covered glass or steel containers when soaking coins in acetone. For some 20 years, I have used two small "plastic" trays for the final acetone rinses. I had purchased these from a dealer in coin collector supplies but after all these years do not remember the material. I have not seen any degradation of the trays from the acetone over all these years. That has given me the idea to use some of the "plastic" prescription containers for acetone soaks. I suspected that material to store medicines would be quite inert to most chemicals. They have relatively tight caps to reduce the evaporation of the acetone. Their small diameter means that only a minimum of fluid is needed. Some of the larger ones will even accommodate a crown size coin, but again with a minimum of excess acetone needed. And I use the clear ones so that I'm able to see the coin inside soaking. I first tested a container by placing only acetone in it for several days and did not visually notice any adverse effects on the container. I have since done the same with coins in the acetone -- again with no visually adverse effects. What do the knowledgable users of acetone say? Perhaps some of the chemists on CT can contribute?
I can vouch for the clear orangish-brown ones. I use more acetone in my faceting hobby than I do in coins, as I superglue the rough onto the dop and after faceting remove it with a soak in one of those overnight. Also seen no problem using with verdicare products. Jim
Common plastics that are safe for acetone are polyethylene, polypropylene, and fluoroplastics (Teflon, Tefzel, etc.). Acetone can migrate through thin polyethylene (think baggie), so over time may disappear if stored in a container made of it. Common plastics that aren't safe are nylon, polyester, vinyl, ABS, and polystyrene. You have to gain some familiarity with plastics and be able to recognize them by look, feel and smell. Application can be a reasonable guide, but you can get fooled. Most food containers are polyethylene or polypropylene (they're usually translucent), but some are polyester (often clear). Prescription vials these days are usually polyethylene or polypropylene or a mix called polyallomer, but they used to be polystyrene and some may still be. Best is to test a small area of plastic with a bit of acetone and see how it reacts. Cal
Thanks, @Desert gem and @calcol, I appreciate your input. The pill vials I have been testing are the orangish-brown ones that one can see through-- the ones Jim referenced. I have not yet tested any of the clear, color-less ones or the white opaque ones.
Huh. I would've sworn the clear amber vials were polystyrene, but I just checked two, and they're PP (polypropylene). I also didn't realize PP was actually acetone-resistant, to be honest.
Clear prescription vials are almost always polysytrene, which is dissolved by acetone. Translucent amber prescription vials are almost always high density polyethylene or polypropylene (OK for acetone). Lids are polyethylene or polypropylene in either case. If you take the lid off and squeeze the rim, polystyrene will feel quite rigid, whereas polyethylene and polypropylene will flex. These vials are designed for pills and capsules. The lids are not liquid-tight. See the pic. Cal
When trying to identify plastics, it's important to realize that clarity and color aren't the same property. Clarity is the degree to which light of one or more colors can be transmitted through the plastic. The three crude degrees of clarity are clear, translucent and opaque. Color refers to the wavelengths of light that can be transmitted (or in some cases, reflected) by the plastic. Look at the two prescription vials in the pic. The one on the left is relatively clear (ignoring the scratches). The one on the right is translucent. Both are amber in color. The polystyrene vial feels much more rigid in the squeeze test than the polypropylene/polyethylene vial on the right. So clarity is an infallible guide ... right? Wrong! Sometimes additives are put in otherwise clear plastics to make them translucent or opaque. You've got to consider all the properties. And the dab test with acetone will often be most revealing. Cal
Yup, hard to go wrong with ceramic, glass, stainless steel or aluminum. Just need to avoid the coins sliding around much so as not to wear or scratch them. For ceramics, they need to be glazed. Acetone will go through unglazed quickly. I use glass bottles to store solvents and small polyethylene dishes for treating coins. Cal
@physics-fan3.14 had some fairly alarming problems from acetone on aluminum coins. Jason, did you ever finish your experiment in that regard? Have you been able to reproduce the problem, and if so, were you able to narrow down the cause?
I was referring to using aluminum containers to hold acetone while dipping coins in it ... not to acetone use on aluminum coins. Cal
Yeah, but until we get to the bottom of that spotting/corrosion issue, I'd be nervous about using an aluminum container at all. I can't off the top of my head think of a mechanism where acetone would react with aluminum to produce something that would then be more likely to damage other metals -- but I can't off the top of my head think how acetone would be attacking aluminum in the first place.
Perhaps... https://www.pfonline.com/articles/aluminum-surface-finishing-corrosion-causes-and-troubleshooting
Yep, that's the reaction that's been brought up previously. I'm interested in their definition of "ambient light" -- often these photoreactions need something much more intense than direct sunlight to proceed at a useful pace. I also noticed that they said this was "relatively uncommon". On the other hand, if anything else had previously caused the acetone to disproportionate to acetic acid and methane, that acetic acid would be sitting around waiting for something to attack. It could build up over time as the stuff is stored, although I can't imagine anyone storing it in a transparent container, in bright light, in contact with copper...
Yes, same Kagwade , et.al. group from Stoney Brook U. seem to be the only ones that found this effect. Not under my envirnomental conditions. Jim
I only use glass - I don't want anything leaching out of plastic. Snd I only use Methylene chloride or Chloroform. If you can't get instrument grade chemicals, I wouldn't use any because you are adding contaminants onto your coins - see milkspots.
Some technical grades of acetone may be only 95% acetone. See the first link below for ACROS (a common lab brand) technical acetone. The acetone sold as painters' solvent may be even less pure. Sometimes the MSDs for painters' acetone will state the purity is 100% or even 100.0% percent. See link 2 below for MSD for Klean Strip (sold by Amazon and Home Depot). If you believe this, I have some MS70 coins dated 1800 to sell you. They make the same ridiculous claim for their toluene. They are more honest for their xylene, which may only be 2/3 pure. Sometimes there can be conflict within the same spec document. In one part of their spec sheet, Sunnyside claims their industrial acetone is 100%, but 99.5% in another part. See link 3. I'm skeptical of the purity of any painters' or other industrial grades of acetone. And would not use a technical or industrial grade on coins regardless of what their spec sheets say. What are the impurities in acetone? A common one is acetic acid, but there are others. Acetone that meets specs as ACS reagent grade (a believable 99.9%) is cheap enough and safe to use on coins. It's widely available as different brands from a variety of sellers. A gallon with tax and shipping can be bought for $75 or less. A gallon will last a long time. Smaller volumes cost less total, but more per ounce. Why not use the best on your coins? Cal Links: 1. https://www.fishersci.co.uk/shop/products/acetone-technical-acros-organics-2/13277983 2. http://www.kleanstrip.com/uploads/documents/GAC18_SDS-LL34.pdf 3. https://www.sunnysidecorp.com/pdfs/Data_Sheet_840G5.pdf
Isn't that because it's really hard to separate all the xylene isomers (ortho, meta, para) from ethylbenzene, and because it doesn't really matter if you're just using it as a solvent? As for the others, IIRC purity is often specified in terms of specific impurities -- in other words, there might be a percent or two of other stuff mixed in that's unlikely to get in your way, but the things that would really interfere with normal usage are more tightly controlled. Of course, acetic acid is kind of a big deal for the acetone uses we have in mind, but I'd think that would also be a problem for other applications (degreasing aluminum or galvanized steel, for example).
I use small glass containers for acetone but it's good to know that some prescription containers will also work.
