Japanese Porcelain Coins

Stork · May 11, 2021 1:11PM

I put a version of this post up on CoinTalk, so if you are a member there this will be familiar. Unfortunately it's not a direct cut and paste due to formatting and photo upload differences, but the gist will be the same. Please add any photos or info if you have any!

The porcelain coins really aren’t precisely porcelain, but a clay mix baked in high heat. Somehow the translation went that way though and the coins carry the name. Their production was at the end of WWII and there has been some debate on various message boards as to whether they circulated officially or unofficially. Most clearly did not, but as one type is much more commonly found, this has been ascribed to it having been out in the wild for a limited time. Or, that the rumor of circulation just a speculation that has been repeated.

--Here is my original purchase (or gift from hubs? I can't remember). The common type in the common color. It is undated, but attributed to 1945, and is the one that may or may not have circulated

The porcelain coins are an interesting little niche, but little literature exists in English, and apparently not much in Japanese either. I probably should do a proper bibliography, but there just isn’t much. But as I have now acquired a small handful, it seems time to organize what little I know.

Jacobs and Verumeule mention little and call the coins red fiber, which they aren’t. Sidebar—red fiber refers to magnesite and was used for some of the overseas issues (Manchukuo specifically). J&V also notes ‘similar patters in clay and other such materials exist’. I question their data because of that, and instead of photos there are drawings—and the 5 and 10 sen illustrations are swapped.

--Here is one of the sets I purchased out of a Stephen Album (auction or directly) with all three denominations.

The Cummings book describes more varieties and has several photo illustrations for type, but does not claim to be an exhaustive representation. He gives the total mintage of 15,000,000 with dated pieces for 1944 and 1945. All other sources (including the JNDA) only give year 20 (1945) as the official dates.

--A second full set, also purchased from Stephen Album (auction or directly). The one sen has a slightly different color and sheen that is well represented in the photo. One of the sources indicates that the denominations were split by where they were minted (dies were used as well as specific planchets, and the process is still a minting style, not casting or molding). In any case, the three different production facilities used somewhat different clay mixtures and drying temperatures. The different appearances would be consistent with different production facilities.

Then, there is Krause (looking at my 2015), which appears to be using the illustrations from the Jacobs and Vermeule book (though they correct the placement of the 5 and 10 sen).

For the single illustrated types shown in J&V regular KM#s are assigned. Content is noted as ‘baked clay’ (vs. the J&V ‘fiber’ or porcelain), with color variations reported. The one sen also is bears the comment ‘circulated unofficially for a few days before the end of WWII in centra Japan’. The 5 and 10 are ‘not issued for circulation.

Moving to the pattern section things are even less clear. For each of the 1, 5, and 10 sen denomination there are two assigned numbers, all dated Yr 20(1945), and all are “(1, 5, or 10) Sen Porcelain Numerous designs exist”. With a third one sen number merely Sen Porcelain. They are listed sequentially as Pn74-79, with Pn74A tacked on last. Sadly I doubt there will ever be any more clarity from the Krause catalog over this. It might be ‘fun’ (not) to go through older/newer editions for changes.

--A recent Japanese auction purchase. Please excuse the askew orientations, it was a quick photo of all three at once to have identical lighting etc. Whether the color differences are due to clay content, baking temperatures, storage, or handling, I don't know. All have been discussed as potential causes.

Numista has 8 examples, though the photo for one is incorrect (a 1 sen vs. the 10 sen). The comments under the common 1 sen is most complete and references two production potteries as well as the unofficial release. Also notes the different colors, and attributes that to baking temperatures. Unfortunately no source material is given.

--More newps from the same Japanese auction. Only the 1 and 5 sen.

The JNDA also only shows representative designs, as drawings only, and lists all under patterns without reference specifically to circulating specimens. By the highly technical method of aiming my phone at the page and engaging Google Translate, this is what I get:

Unissued 10 sen pottery (10 sen porcelain in English)
Manufactured by Matzukazi Co., Ltd. Kyoto City
Showa 20 (Manufactured in 1945) Trial Casting
Diameter 21.9 mm
Grade feldspar 10-15% Ground Powder 85-90%
(the name of the company was translated several different ways, the one I chose was reflected in another source).

Unissued 5 sen pottery (5 sen porcelain in English)
Seto Wade Pottery Co., Ltd. Aichi Prefecture
Showa 20 (Manufactured 1945) Trial Casting
Diameter 18 mm
Grade university (?) clay 90%/Limonite 10%

Unissued 1 sen pottery (1 sen porcelain in English)
Arita Town, Saga Prefecture, Kyowa Shinko Pottery Co., Ltd and manufactured in Seto, Kyoto
Showa 20(1945)**
Diameter 15 mm
Grade Mimasaka clay 60%, Izumiyama stone 15% Akame Clay 15% Other 105
**Interestingly the coin illustrated is the common Mt. Fuji 1 sen which allegedly or possibly ‘circulated’ for a day or so. THIS entry in the JNDA does NOT include the ’Trial Casting’ kanji.

_--The last group from the same auction. Finally my first white porcelain coins! Still would like the 10 sen here too, but happy to have a new design with the rice as well as the new color. _

And finally, I stumbled across a 1973 World Coins ‘gold edition’ monthly publication which included a brief article on the topic by Thomas Alvin Norris III. Google does not reveal much, but he was an advertiser in the publication as well. And includes footnotes and references which I was unfortunately unable to track down. He uses the term ‘toka’ for the coins. He gives a timeline for the Mint’s efforts in producing the coins.

In any case, they came about at the latter part of WWII. As metals were needed for war efforts the smaller denomination coins went through iterations of progressively lighter aluminum and eventually tin. The Japanese Mint went looking for more options. Paper was one, but attention was also turned to non-metallic coin options. Porcelain coins were known from Germany after WWI, the notgeld so it was a known option.

The Mint officials eventually produced designs and methods to mass produce the coins. Being clay, the task was given to three major potteries that had the size, materials (clay and coal),manpower, and ability to mint to specification. Unlike metal coins a different kind of ‘shrinkage’ had to be accounted for—drying the clay resulted in a 1-1.5 mm decrease in diameter.

Production issues such as uneven heating, cracking, sticking together were noted. But the final products were uniform in diameter/thickness, were sturdy enough to be handled, and retained the design features required including concave surfaces and two step rims.

Some have more of a sheen which relates to the proportion of feldspar apparently. And color variances are due to relative content per this source. It appears from the Norris article that the color difference was intentional for each denomination and the planned colors ranging from chocolate, to reddish-brown, to red. But also, white and black examples are known as samples. Up to 91 varieties have been noted, but not confirmed by the sources uses.

The three factory potteries utilized were in Kyoto, Seto, and Arita. Interestingly each apparently had a unique specific content to the clay, which I suspect was related to availability of local product. The varying content noted reflects the JNDA.

Between designing the coins, determining content and specifications, die production and producing the minting machines it took quite some time to ramp up production of the actual coins. Plus some machinery was destroyed. First meetings were held in early 1944, and mass production began in July 1945.

According to the World Coins Norris article total mintages were:

— Kyoto (1 and 10 sen) 3 million
—Seto (1 and 5 sen) 2 million
—Arita (1 sen) 1 million

And because the government wanted to wait until sufficient quantities were ready before wide release, this did not happen as the war ended in August. But this article also specifically states “Although these coins were never officially released, some one sen toka circulated for one day in Osaka”.

I wish I could read his sources! In any case, most were ground and destroyed, and the rest are what trade amongst collectors.

And finally, what do the TPG say? All I could tell from the NGC census is there are two clay 5 sen pieces dated 1945 in slabs. No 1 or 10 sens are in the reports. No photos that I’ve found yet.

PCGS has four 1 sen patterns (a couple Pn74 and PN75 and I wish I knew how they decided which was which and what about the other styles).
https://www.pcgs.com/valueview/1-sen-1869-1958/1945-h20-p1-sen-km-pn74/4834?sn=418415&h=pop

https://www.pcgs.com/valueview/1-sen-1869-1958/1945-s20-p1-sen-km-pn75/4834?sn=620838&h=pop

https://www.pcgs.com/valueview/1-sen-1869-1958/1945-h20-p1-sen/4834?sn=418414&h=pop

three 5 sen
https://www.pcgs.com/valueview/5-sen-1869-1958/1945-s20-p5-sen/4835?sn=418416&h=pop

https://www.pcgs.com/valueview/5-sen-1869-1958/1945-s20-p5-sen/4835?sn=418417&h=pop

and three 10 sen
https://www.pcgs.com/valueview/10-sen-1869-1958/1945-s20-p10-sen-km-pn79/4836?sn=418419&h=pop

https://www.pcgs.com/valueview/10-sen-1869-1958/1945-s20-p10-sen-km-pn78/4836?sn=418418&h=pop

At some point I will try and add some auction listings as well.

291fifth · May 11, 2021 2:31PM

Great post! It is something I have never heard of before.

MasonG · May 11, 2021 2:40PM

Very cool. Now I think I need to get one.

Stork · May 19, 2021 8:07PM

Newp. Plus someone on another site asked about the relative diameters, and when my new prize came in I made sure to take one shot with all in the same view, before making the usual combo shot (exposure tweaked in this case).

15 mm, 18 mm, 21 (or 21.9) mm diameters.

Group shot for detail not relative: