Up until recently I have never seen the attraction in brass inlayed tsuba typified by the Onin, Heianjo, Yoshiro and Jingo schools, to my mind, gold is a much classier metal for inlay. However, I saw one at auction recently and decided to buy it as it was in great condition; only one section of about 1 cm of fine inlay was missing. I have attributed the tsuba to the Kaga Yoshiro school, as several other very similar examples attributed to this school appear in books (Peabody Museum E31250) or are currently for sale (e.g RiceCracker.com). The combination of bell flowers (with five petals) and asymmetric ‘V’ shaped leaves on the vine seem characteristic of this off-shoot of the Heianjo school. After studying the tsuba for a while I have begun to appreciate its charm. It has also raised a few questions regarding the iron base plate of the tsuba.
In most of the examples of Heianjo/Yoshiro brass inlay tsuba I have come across, admittedly mainly in books or through a glass cabinet at a museum, the inlay looks fairly flush with the smooth iron plate, or the plate is described as ‘lightly hammered’ if it is not perfectly smooth. The plate on this one has a granular appearance, as if etched with acid (see photos). The tsuba looks as if has had brass inlay applied to a flat iron plate, the brass masked with a protective coating and immersed in acid to remove about 0.5mm of iron, but maybe the whole plate has this texture and was etched before the inlay was applied. I’m surmising that the granular appearance is due to a mixture of different steels in the plate dissolving at different rates. To support this assumption I remember as a kid dropping a copper penny into nitric acid and watching it dissolve. The penny just got thinner and thinner, but the embossed design remained visible, the dissolution process occurring at the same rate over the homogeneous metal. I would expect that ‘lightly hammering’ the plate would produce smooth indentations, not the granular appearance seen on this tsuba. Perhaps this tsuba had become heavily rusted and has been restored, but I don’t think so, the surface is too even, whereas rusting would mostly likely be confined to specific areas. So, first questions, do others out there think that the tsuba has been acid etched and how common was this procedure?
The granular appearance raises another question. The parts that stick up from the surface areas are probably harder steel/iron and so can they be considered as tekkotsu (iron bones)? OK, I agree that they are not the classic tekkotsu that I have seen on the rims of tsuba arising from the forging process, but…..
The final question that I have regarding this tsuba is the patina. There is no rust on this tsuba and the shine on the patina of the iron looks as if it has been waxed, coated with lacquer in historical times, or polyurethane in recent times (Ugh!). This type of tsuba was popular around 1600 but looks as if could have been made yesterday, but I hope not. It has either been treasured over the centuries, or may be a later copy of this popular design. Apart from the gloss on the iron there is no other sign of a coating, e.g. worn areas, edges to the coating. Two other iron tsuba from the same auction lot have normal patina, so I can’t attribute the gloss to the previous owner. Any thoughts?
Dimensions: Height: 7.7 cm, Width: 7.5 cm, Thickness: 0.4 cm
Best regards, John (just a guy making observations, asking questions and trying to learn)