Ken,
You very nicely quoted something my (now gone) mother POUNDED into me when I was younger involving keeping my mouth shut!
In my case it is not disagreement with use of Pre-Lim, but simply not having any experience with it. I do agree, though, it is a very touchy subject. After your post and some googling I actually ordered some Pre-Lim to try for a specific situation, which I'll detail later.
1. I noticed that Pre-Lim does have some adherents within the ranks of museum conservators, but I could not find any published info from them about it's use on coins. Other metal artifacts, yes, but coins, no. The use of harsher methods is more typical (from my reading) for spear points and bracelets (at least not gold ones) because proper classification of the object, especially if it involves an on-going archaeological dig, outranks almost all other goals. Thus use of harsh chemical stripping or
electrolysis to enable faster
identification. This is referenced in quite a few papers and books I've read on conservation (at least those published 15 or more years ago).
2. Coins are usually (though not always) treated somewhat differently. I suspect it's because they occupy a special place between useful metal implements and works of art. The closer a person is to viewing
cons as artistic artifacts, the more likely it is that ever more gentle cleaning methods are used, and that would normally preclude the use of ANY abrasive polishing agent.
3. Someone who is closer to the "coins are art" would then clean coins very gently. Furthermore, they would normally clean coins ONLY until the coin could be clearly attributed and no further. Examples are coins that are cleaned but have some deposits remaining.
4. I used to be more in that camp, but have recently (in past year, or so) moved further in the opposite direction. I am now more interested in trying to get a coin to look the best it can be, considering its specific state, which can vary from very
poor to pretty nice. NOTE that this does NOT mean getting a coin completely clean because many coins look better AND are more legible if a
bit of stuff is left surrounding or within specific areas of the coin (great examples are desert patinas and other coins that have a
bit of dusty stuff remaining).
5. So I didn't reply because of lack of experience with Pre-Lim. I also am personally VERY selective anymore regarding applying ANY liquid to a coin. I have absolutely ruined some coins with nothing but distilled water. If any surface or
patina is showing, I clean a coin almost exclusively mechanically. if completely dirt covered, I'll use gentle water-based chemical solutions (another topic) to loosen things up.
6. The situation I'm interested in where Pre-Lim might be useful is this one: late
Roman coin, dirt covered exclusively. Once I begin cleaning it with my
tools, the only liquid that normally touches the coin is saliva (don't ask). So I scrape and scrape and poke and poke, and scrape some more (under binocular microscope). Eventually I get to a place where ALMOST everything is clean, but sometimes there's a
bit of stuff clinging to the surface that I just can't seem to get off.
7. I've been trying various methods - some of them involving liquids - and some using abrasive
tools such as fiberglass pens used for cleaning smutz off electrical connections. I noticed that Pre-Lim is basically a slurry that includes silica abrasives, which is sand of some very small size, so it is not conceptually different from me using fiberglass pens. I worry about the control I'd have with Pre-Lim, but that's why we experiment on culls, so I'll see when it gets here. My concern about abrasives is that they could "round off the edges" of design elements on the coin and damage its appearance and potentially leave visible marks (my goal is always to leave no marks visible under my microscope, though after 18 years cleaning coins I don't always succeed).
8. Yeah, most people would consider removing marks within a
patina with an abrasive substance to be polishing. My goal is always leave no marks, but as I say that, it's a GOAL, and not always achieved. If you are going to clean coins, you will almost always damage something you would rather not, which is why we start gentle and only pull out the steel punch and hammer for certain problems (yes, have actually used that, but a topic for another day).
Last topic for now and addresses your last paragraph. Dude, just tell the modern-coin-collector-no-cleaning-bullcrud to pound sand. They have their world and we have ours. we mostly don't even speak the same language. Theirs is the world of lovely coins viewable only through sealed plastic cases, where a fingerprint can cause a coin to loose half its value. Our coins are objects we TOUCH, and treasure.
Thanks for your post, Ken. I haven't posted much here in the past 15 years and was completely focused on other things for most of that time though I was active on the boards before that. Now thankfully retired. Your post got the old blood pumping so maybe I'll post some of the stuff I'm working on lately. I'm just too darned wordy...
Mark