Hi everyone, my order for some uncleaned Roman coins just came in from Nero coins, and I got to work right away. Nine of the ten that I ordered are currently soaking in distilled water and it's going quite well, and the last one didn't really look like it needed a soak. I could already attribute it and the buildup on it looked like the same stuff on this coin. I used MS-70 on this new one and it worked some, enough for me to attribute it, but I need to get more of the buildup off to properly conserve the coin. It's a posthumous issue of the deified Constantine that I found pretty quickly in the RIC (given that there's only two of them). What gave it away as a posthumous issue right out of the box was the veiled head that I'd recognize anywhere. VN MR; Constantine, veiled, stg. r.. O1/17; veiled hd. r.. AE4, X.XXg I haven't weighed it yet, I'll save that for when the conservation is complete. I will admit, I don't know what the "O1/17" means, I'm just copying from the RIC. I'm happy to have one, it'll make it easy to attribute these coins once they're done soaking. I've seen some radiate crowns and one that looks like an issue of Theodosius which I'm excited about. These coins provide a fun and inexpensive way to bolster my collection of late imperial bronzes; I only paid about 45 dollars for these ten which figures to 4 and a half dollars per coin which I can't complain about. That's all for now, I'll update regularly with more.
Looking good so far @Noah Worke I have a very cheap (2 euros) coin which I have no idea how to reveal any details. It has a thick, jet black and rock hard encrustation all over. 10 days in distilled water baths has not loosened anything. I can make out a veiled bust of Constantine 1 and possibly Aequitas on the reverse.
I wouldn't go much further cleaning this coin. Additional cleaning would eliminate more of the dark deposit, but it will also reduce contrast. If all contrast is removed the result will be a more unattractive coin with bright rough surfaces, making attribution more difficult. Just my opinion.
Yeah I was afraid that would happen; I don't expect to go much further. Surprisingly when the coin arrived, it was already pretty bright which is why I skipped on the distilled water for this one. I don't know why it was so bright, but I agree the contrast does help with legibility. My only hope is that the acetone makes the legend clearer, so I can figure out which of the three obverse legends it has.
The metal that was used in Rome in imperial times was orichalcum, what we call brass, which is composed of a combination of copper and zinc. Bronze, on the other hand, is an alloy of copper and tin. Now I am not sure what proportions of copper and tin was used, but the yellow color is very distinct from the red of bronze. I think this is a factor on how quickly an orichalcum coin tones, versus one that is bronze. I think this is also a factor on how long a coin, once cleaned tones again. There are agents, notably liver of sulfur, that can accelerate the process, but even the use of this chemical has limits. I have brass objects that have not really changed much in color over the years. On the other hand I have bronze coins that change (darken) rather quickly. I attribute this difference to the amount of copper in the alloy. My Byzantine bronze coins must have a high copper content, since they tend to tone more quickly compared to Roman imperial orichalcum coins. This is coin that I bought recently. It was excessively cleaned in my view, with bright shiny surfaces in areas, along with heavy deposits over much of the coin, especially on the obverse. Unfortunately I don't have "before" photos; I was quite intent on attending to the coin. Some areas were heavily encrusted with heavy black deposits. There are also those rock hard green deposits. My objective was to mitigate the deposits, but not eliminate them entirely. I also needed to adjust the color so that it is darker and more in agreement with the deposits. Using chemicals on coins is a fraught undertaking and I don't recommend using them without knowing their effects. One can never be absolutely certain about the condition of the underlying metal, which could be corroded. There is an element of luck and in this case the surfaces are intact. The deposits were treated first with the coin immersed in distilled water to loosen up any soft deposits. This yielded very minimal results. The next step was to apply naval jelly only on the areas of heavy deposits, not the entire coin. This was done with cotton swabs and wooden toothpicks. Many applications were done in succession, taking care not to allow the acid to stay on the surface for more than roughly 30 seconds, followed by rinsing with distilled water, drying, and examination. Once the deposits were at "acceptable" levels (totally subjective), the coin was treated with diluted (with very hot distilled water) liver of sulfur. I forgot the ratio, but it was around 5-6 drops to roughly two tablespoons of distilled water. Again, cotton swabs were used on applying, followed by distilled water rinses. The coin did darken, not as much as it would if it were bronze, but the cleaned surfaces are quite apparent, nothing can be done about that. Note that the deposits are still there, along with some green spots. Generally I don't like treating ancient coins this way. I'm from the school of live and let live, but sometimes a coin can be helped with measured and knowledgeable treatment. Vespasian, AE dupondius, Rome, 74 AD, COS VI. RIC 567 12.63 grams
I haven't heard of using naval jelly to loosen up deposits, I'll have to try that on one of my corroded bronzes. About chemicals, I agree. I used acetone to try and loosen up some of the encrustations on my other coins, and for the most part that's what it did. I don't have any before pictures but the cleaning is a slow-going process, so many of the coins don't look too different. One of them I was kind of disappointed once I removed the dirt, because there was a large corroded pit right on the face of the portrait. I hope the legend hasn't really been affected so I can find out who it was.
You need to be very careful using naval jelly. It contains sulfuric acid and should be treated as a "last resort" treatment. Long soaks in distilled water is the best approach initially. Some deposits, such as those concrete green deposits, are benign (not bronze disease) are are best left as is.
More phosphoric than sulfuric... Naval Jelly contains Water (65-70%), Phosphoric acid (25-30%) and Sulfuric acid (1-3%) in a gel matrix composed of a thixotropic polysaccharide (1-3%), isopropanol (1-3%), Surfactant (1-3%) and Silica (0.1-1%).Oct 17, 2022 Naval Jelly Rust Dissolver - MFA CAMEO Database
I have one that just came in from my second order (I'm leaving all of them alone for now to soak in distilled water) and it seems to be in fairly good condition. The reverse is pretty legible already, so I'll see how it looks this afternoon after a day of soaking. I may not even need to scrape much of the dirt off. The reverse legend reads SECVRITAS REIPVBLICAE which seems to be a type attributed only to Valens. I'll take a closer look and post photos when I get home, but this might be my second Identifiable coin that I've been cleaning. Out of the 20 that I bought I have 14 soaking in distilled water, and five of the worst in olive oil. I just bought some picks the other day which helped me get rid of the worst of the dirt on most of the coins, but it's a double-edged sword as I did scrape some of the metal unfortunately. Nothing distracting, but still a reminder to be more careful.
Here's the SECVRITAS REIPVBLICAE: The obverse seems much less clear than the reverse, but it looks like perhaps something is covering it. Only way to find out will be more distilled water.
Here's another two. Both have this greenish coating that's obscuring some of the detail. On the radiate I'm pretty sure it's verdigris, but the other one has a much mellower color and I'm unsure. The radiate, unfortunately, bore the brunt of my barbaric pick-handling skills. Luckily they're nothing too valuable, but nonetheless they are still nice coins and I'm a little disappointed in myself.
SECVRITAS REIPVBLICA after distilled water and some MS-70. Reverse legend is legible and the reverse is readily Identifiable which is nice. The obverse is a little more of a challenge, because the first part of the legend is obscured so I'll have a hard time finding out who had this minted. I'm sure there's some marker that I can use to determine that. This one is also difficult to Identify, again because the legend is obscured. I think it might be a base metal denarius because of the laureate head of the emperor on the obverse. I can make out PIVS P COS III on the obverse but the actual emperor's name will be difficult to find.
When using a sharp pointed object it is best to use the point in an almost horizontal position to the coin surface, and ALWAYS use a circular motion. This is a way to minimise damage if you accidentally press to hard. Slightly rounded marks are less obtrusive than vertical or horizontal scratches.
I took a look at it through a loupe and I'm pretty sure this is Valentinian. This second pic is a reference from Numista and everything seems to match, down to the mint marks. Thankfully the name on this one is split because the left side of the coin is completely illegible.
I followed @expat 's advice and used small circles parallel to the coin's surface. This green coatingwas practically falling off, so I got rid of it as you see here. The legend is still raised, so I don't think I've damaged anything but I wanted some advice or some comments before I go any further. It's likely that I won't touch the devices because they're probably going to need the contrast. Since I'm pretty sure it's Valentinian the first part of the legend doesn't matter too much to me, so I tried to see if I could excavate it. I'm pretty sure the whole thing's destroyed since I didn't see anything. Any recommendations going forward? Thanks for looking.
