Scans

 This weekend was pretty low key. I found a gym near the Cite to play badminton and I did that Friday night. It's the first use I got out of my racquet in a couple weeks and it felt fantastic to be able to blow off some steam. The guys at the gym are around my level or lower, but the guy who seems to be in charge told me of another place to go where the people are much better. He also told me about a tournament on Saturday, which I went watched for a little.  The two gyms operate on different days, so I may be able to play at both. It's going to cost 20e to play for 2 months, which is a lot less that I was expecting.

After watching a little bit of the tournament, I went to Place de Bastille and Pere Lachaise. Shame on the people who run Pere Lachaise, because Fourier isn't on their list of famous people buried there. His grave was easy to find, luckily. Chopin's, however, was not so easy to find.

Last night around 0300 the fire alarm in our building went off. It was turned off around 0315. And promptly went off again. And was turned off 10 minutes later. And promptly went off again. This continued for a while. The upshot was that around 0340 we all came back inside at which point the alarm went off AGAIN and we ignored it, but it's hard to fall asleep when the alarm is right outside one's door. It was shut off for good, thankfully, around 0400. I'm feeling a little sleep-deprived as a result.

Below are high-res scans of the coins I'll be ablating some time in the next month.

Top row: Three Kanei Tsuuhou Japanese coins. The first one (leftmost) was kept as-is from the seller, while the middle and rightmost were scrubbed and then soaked in soapy water for 2 days. Nonetheless, the rightmost coin still looks quite dirty. I'm going to name all the coins here for future shorthand/reference. The one on the top left I'll call KETH kanji, because the characters are easily and clearly visible compared to the middle two.  The middle one I'll call KETH kurai, since kurai is the Japanese word for dark. The last one I'll call KETH kitanai because it's quite dirty. I'm interested to see what happens when we ablate around the edges of the characters, especially the somewhat-complicated "kan" on the coin's north. Also, I believe that the coins may be from different mints. I was reading online that the length of the leg on the "kan" character is indicative of different mints. Look carefully at that character. In the leftmost coin, the leg stops before the edge of the coin's central square, whereas with the other two, the leg is flush with or just exceeds the square. Moreover, the characters, especially the "hou" on the coin's East seem more well defined for the leftmost coin. I wonder if the different mints would have different concentrations.

The lower two coins are two American silver dimes. Because the years are vastly different, I'll just use those as tags. Thus the left dime will be ASD54 and the right ASD46. The coins are nominally 90% silver and 10% copper. ASD54 seems to be in particularly bad shape, and ASD46 has a greenish corrosion covering most of FDR's face.

The obverse of the above described coins. The waves on the back of the Japanese coins look like a good place to irradiate without worrying about scattering from coin features. ASD54 was minted in San Francisco, which is pretty cool, especially since minting stopped there the following year for generally circulated coins.

Above are two world war era American nickels. The concentration is nominally 56/35/9 Copper/Silver/Manganese. As these two coins are from the same year, I'll have to be more creative than with the dimes. I'll call them AN44L for the left one (for light-grey) and AN44D for the right one (for dark-grey). I'm actually very interested in these two coins because they exhibit similar coverage by differently-colored corrosion products. I want to try irradiating the coins in the same area, Jefferson's collar looks promising, with fluences well below the ablation threshold for copper (1.06 J/cm^2) and see if the "gunk" of either pedigree gives way.

Obverse of the above nickels. 

Two other world war two nickels. The one on the left is in particularly bad shape and seems to have scratch marks, perhaps from earlier cleaning attempts. The left side exhibits reddish corrosion, while the right exhibits black. Again, this could be an interesting basis of comparison for two types. I'll call the left coin AN43. The coin on the right is in fairly good shape, and seems to have corrosion of the same color as AN44L. If cleaning on AN44L is moderately successful, I'd like to have a go at trying to clean this coin completely. I'll refer to is as AN44CC for that reason.

Obverse of above nickels

Front of a Roman coin minted in Thessalonica somewhere between 348 and 351 AD, during the reign of Emperor Constans or shortly following his assassination. The coin is 17mm and 1.51 grams, but other than that, I've been able to find astonishingly little about the metalurgical composition of this coin other than "bronze".  Most of the coins Serafinites et al cleaned were minted earlier, so while they might be good for an approximation, they cannot be considered gospel. An image of what the un-corroded would look like is here. 

Obverse of the Roman coin. I really don't have a plan for this guy yet. The thin green corrosion layer is similar to what Serafinites dealt with, but he was more successful at shorter wavelengths and we're using ~800nm. Perhaps the fact that we're using fs instead of ns pulses will yield different results (less thermal effects).