Treatment of Tsuba - Recovering Patina

[Martin]

Hi all,

 

I have 2 questions regarding the treatment of iron (Sukashi) Tsuba:

 

1)

Sometimes you may find some shiny spots on the surface where the patina has gone.

I was wondering if anybody could share some experience (or practical advice) on maintaining / restoring patina on iron Tsuba or on ways to let it recover itself.

 

2)

Why is it a big NoNo to remove the (red) rust from the walls of a Sukashi Tsuba whereas it seems to be appropriate to remove it on the front and back surface with ivory or bone?

 

Thanks in advance,

Martin

[Ford Hallam]

Hello Martin,

 

you raise some very important questions here. This also gives me a chance to answer Brian's question on the same topic.

 

Firstly, it's important to understand what a patina actually is. On iron and steel this basically comprises iron oxides ( I won't bore anyone with chemical compositions ) , oxidised oils and various other inorganic trace material. There are two iron oxides which we are presented with on a tsuba. A black one that is relatively stable and offers a fairly good protective finish, and a red one, hydrous ferric oxide, the warning sign is the "hydrous" bit, this means there is moisture present. Red oxide is, as most know, still active. This means that there is an ongoing chemical reaction by which iron is being converted into it's oxide. There is an electrochemical breakdown of the iron, it's as though there is a little reverse plating process underway, electro-stripping. Left unchecked the iron will ultimately be entirely consumed.

 

It is possible to pick away the larger flakes of red rust but unless the metal is then dried, and remember metal is quite porous on a microscopic level, and the tiny gaps in the metal plugged with something, moisture will eventually find it's way back in. ( You could of course keep your tsuba in a drying chamber, what called a desiccating chamber. ) This is where oxidised oils help. I won't describe the actual procedure as it really is more of an art than an exact science and frankly, I'd hate to be the cause of a whole generation of collectors oil blackening their tsuba. It's a far more delicate process. The other thing that must be done is to convert the red rust to black rust, again not a task for an amateur.

 

In terms of touching up rubbed patina on the face of a tsuba, we are again faced with a similar problem, we need to create rust, and then stabilise it. It must also be only a surface skin, not a heavy coating of oxide, as this will simply keep eating away at the tsuba. I couldn't really advise on any fail safe procedures that are suitable for general use.

 

As you mention, it is generally advised that we don't touch the inside walls of the cut-outs. This is mainly for the same reason we don't clean the tang on a blade. It reveals a lot about the age of the piece but there is also an aesthetic aspect to saving this sign of age. I will dare to go against convention and suggest that there are times when very careful and sympathetic cleaning is desirable, and in some cases essential. Again, I will emphasise that this is not really a job for an amateur.

 

I'm sorry if this all sounds as though a bit complicated but if you have an important tsuba in your care you have a very complex article to conserve and the basic material is very delicate. Preserving, or retouching the original colour is even more exacting.

 

In many ways this work in no less demanding than restoring old Master paintings. No one today would dream of having a go themselves if they owned a valuable old oil painting. In the past many collectors did though! Thankfully conservators have developed far more reliable and safe processes and much of the damage of the past has been rectified. Sadly though, some artworks have been irretrievably lost to us due to well meaning, but inept attempts at restoration in the past.

 

As a professional restorer I have seen a lot of such poor "restoration". In almost every case the job of correcting the earlier work is now even more complicated. On top of which, there is inevitably so much information that has been lost through inexpert handling. An untouched piece in need of help has so much to tell an experienced eye. This helps to establish what the final appearance should be and it is then also possible to accurately recreate the working processes of the maker.

 

Finally, on a more practical level, handling iron tsuba with bare hands is also a matter of some debate. There are those who maintain that the oils from your hand add to the patina and so tsuba benefit from being caressed. This is a big part of the tactile appeal of these things. There are, however, some people who have what we call in the trade, "acid hands". I had an apprentice a few years ago who literally left rusty fingerprints on tools. Needless to say we decided this wasn't the best career for him. These afflicted :D folks should either wear cotton gloves or be barred from owning tsuba.

 

I didn't mean to ramble on like this, I'd hoped to be able to offer some safe tips but as I started writing and thinking about the problem I realised that much of what I take for granted in my work is in fact highly specialised and almost impossible to convey just in words. What is known as tacit knowledge, or kan, in Japanese.

 

regards, Ford

[Pete Klein]

So I guess what you're saying is that you kan and we kan't?

[Ford Hallam]

Pete!

 

I don't know whether to applaud or to groan, very good though. :D

 

cheers, Ford