I found this Ko-Umetada tsuba at Colin Griffiths Fine Art this morning.
The most well known name in this school is Umetada Myoju (Momoyama Period, 1573 to 1603) but it's generally believed that the name Myoju was actually used by a group tsuba-shi in the earlier Muromachi period (1333 to 1573). Almost nothing concrete is known about the origins of these workers and even the connection to the later, Umatada Myoju school is tentative. Those examples that are identified as belonging to this earlier group are generally unsigned and are called Ko-Umetada.
Tsuba associated with the Umetada group that date from after the time of Umetada Myoju are generally very distinctive. Their inlay designs are reminiscent of the exuberant Kōrin school
and unlike earlier Umetada works are most commonly in soft metals, typically shinchu (a type of Japanese, low zinc brass) and feature painterly inlay in shakudo and other alloys. You can see some of these types here.
The Umetada did produce iron guards after the time of Myoju but their character is generally influenced by the more "plastic" qualities their non-ferrous works exhibit.
The example that caught me eye this morning is quite unlike these later Umetada works I feel.
There is a suggestion of Shoami design sensibility here which is to be expected, apparently, according to Sasano. He also tells us these earlier Umetada works, Ko-Umetada, while reminiscent of Ko-Shoami are more refined. I assume he means in terms of the actual material itself and the workmanship.
The first thing that strikes me about this piece is the openwork design itself. The spacings and volumes are perfectly conceived and the rhythm of curves that are created give the piece a lively elegance. I particularly like the way the lines run into the seppa-dai at the top and bottom and onto the edges of those peculiar hitsu-ana shapes.
The piecing and refinement of those cut outs is skilfully executed. The nakago ana seems to me to be practically unaltered and is a very pleasing shape that suggests to a maker who was extremely conscious of even the most seemingly minor aspects of his work. The rough texture of the kuchi-beni, for me, provides a satisfying contrast to the surface of the steel.
The outer skin of the steel exhibits quite a fine texture and indicates to me a material that has been thoroughly forged to produce a fairly homogeneous steel but being hand made, so to speak, it retains a beautiful subtlety that is impossible to develop in modern mass produced steels. This texture is not the sort that would be applied by means of hammering or a finely textured punch. Rather, the steel would have been finished fairly finely and then, by means of various heating and oxidising processes, the outer layer of material is very gently oxidised away to reveal the more natural skin underneath. This sort of subtle finishing reveals the inner structure of the steel.
The image is a bit over exposed so the true colour is impossible to gauge but I don't see any obvious damage so I would be reasonably confidant that the surface patina is in good condition. Certainly, the overall condition of the piece strongly supports my instinct. We don't have images of the rim but there are at least 2 place near the edge where I discern what appear to be hints of fine linear tekkotsu and some indications of layers in the material so I would expect to see some more signs of the forging process evident in the mimi too.
Genuine Ko-Umetada tsuba are not at all very common and this example is quite large by comparison to those I've seen. Whether a shinsa panel would agree that this is in fact Ko-Umetada remains to be seen but as a good example of a real samurai tsuba this is a pretty fine example and at this price ($500) you really can't go wrong. That it has, in my opinion, a reasonable chance of being papered as being at least Hozon, maybe even higher given it's size, condition and elegance, to Ko-Umatada makes it an extremely tempting offering.