Verdigris Problems on ko-kinko wave tsuba

[Zantetsuken]

Hi everyone,

 

I got a new Tsuba. In hand I recognized old wax on the surface. I gently removed it with mineral spirits. Now the full extent of verdigris is visible. Immediately after laying it in a jar with mineral spirits, the wax, some dirt and verdigris particles were removed and the liquid turned grey-greenish. The wax wasn’t coloured, but still camouflaged the now fully visible extent of verdigris. I already have experience with removing verdigris under the microscope with horn/bamboo tools, but it’s very time consuming. In this case, there will still be patina problems / abraded areas after removing the verdigris.

Is professional repatination economically wise or should I just remove some / all of the verdigris and rewax it with renaissance wax?

Thanks a lot,

Simon

 

 

[Zantetsuken]

First two hours of work done. Lightning condition is slightly different, very hard to make reliable before and after pictures. It definitely looks better now. I attacked many areas moderately and didn’t focus to perfectly remove zone after zone. In some places the corrosion compromised the underlying metals and caused light scaring / pitting. 
 

stuff used:

- binocular microscope 20x magnification 
-fresh bamboo toothpicks and carved pieces from fresh bamboo chopsticks (those are softer and have a lower mohs hardness compared to older, long dried and higher quality bamboo)

-new baby tooth brush and neutral soap (only with medical quality distilled water to prevent lime build-up). This removes the residue composed of verdigris and abraded bamboo particles

-99,9% ethanol for rinsing

-Mineral spirits for a final bath to remove further traces of wax particles that were loosened while cleaning.

 

Still a lot of work to do, probably 10-15 hours.

[Bugyotsuji]

Great work, Simon, looking a lot better already.

 

Everyone was giving you like signs, but waiting to see who would enlighten us first! 

[Zantetsuken]

Thanks, Piers!

I will post further progress here and also tools I‘ll use. I have pretty much experience in restoring wood and iron antiques, but not so much on soft metals yet. 
the verdigris must urgently be addressed. It looks like the wax trapped some moisture and it got worse. The longer it sits, the more scaring and pitting occurs. I‘ll store it especially dry while working on it. 
I‘m always happy for further advice to refine my procedure.

[Matsunoki]

I have used this product in the past on both bronze and copper with some amazing results. Great patience and care is needed…..all the usual toothpicks etc etc.  I used to place items in a bath of it to start with and then work slowly. Haven’t used it lately (it went out of production but is back now) but from memory it also leaves a protective coating.

https://verdi.care/?srsltid=AfmBOopfmM98iXEsjHu4UW_hFPrZ4Jq44pagEBJpCCIZjs6uU-FWXg5q

[ROKUJURO]

Avoiding grease or fatty substances on copper alloys will help prevent green corrosion.

[Zantetsuken]

Thanks for the link to this product. The  liquid seems to strip off quite a bit. Personally I prefer a cleaned only look. My tsuba is about 400+ years old and I don’t know the chemical composition, so definitely a mechanical only cleaning. Shakudo patina seems to be incredibly thin and prone to chemical reactions (sweat, sulphur, acids, sebum etc.). After using chemicals, i‘d need a full repolish and repatination with rokusho. Still not sure this is economically wise. This will probably cost more than the tsuba is valued at.
I also discovered the „silver balls“ to be of lead and not silver. Not sure how lead reacts. To many variables for me to use something like this.

[Bugyotsuji]

With Shakudo tsuba many people in Japan recommend wearing soft cotton gloves, i.e. no bare hands.

[Matsunoki]

1 hour ago, Zantetsuken said:

The  liquid seems to strip off quite a bit.

That depends on how you use it and how vigorous you are….it isn’t harsh. 

[Franco]

Insight, a professional restorer would use both mechanical and chemical treatments depending upon what is found. This, in order to ensure the surface is stripped absolutely clean. Otherwise, there could be failure in the re-patination process resulting in an ununiformed finish. One shakudo tsuba I had professionally restored took five (tedious, careful, time consuming) mechanical cleanings before being chemically prepared for re-patination.

 

Even then the success of the re-patination will depend upon the quality of the shakudo. Which to some extent will be an unknown factor.  Eventually, the quality of the shakudo will become apparent in the final result. On an excellent shakudo tsuba the finish will continue to re-patinate and improve, even dramatically, over time. 

 

With this wave tsuba, not only is there the body to restore but the rim needs attention, too. Then there is the question of what to do about all of the silver? and/or gold? drops that are missing?

 

Value? Worth restoring? Kantei gives an answer. 

 

Good luck.

[Curran]

Interesting thread.

I fear verdigris on copper or shakudo  >much more> than I fear rust on iron tsuba .  [That partially depends on the school's iron and time in history. Some schools, if they get rust... it is a long long time to heal them.]

 

Sometimes verdigris does a real doozy on otherwise very good ko-kinko tsuba.

Ford H. and others gave good advice on verdigris.

I'm glad to see someone sharing their struggle with chemistry and copper based tsuba.

 

 

[cluckdaddy76]

I have used EVOO with a Q-Tip as someone suggested this to me and it worked perfectly on my kinko tsuba to get rid of the verdigris.

 

Jason

[Zantetsuken]

Hi guys,

 

here’s the final update.

As you can see in the before pictures of the tsuba, there’s a hazy greyish layer on the surface. This got worse within hours after removing most of the wax/oil and the following exposure to oxygen. This is especially visible around the abraded spots of the seppa-dai area. Whatever had been in contact with the tsuba altered the surface structure and made it more prone to oxidation/ corrosion. I wanted to make sure this isn’t accelerated by polymerized wax /oil layers left on the surface, but a couple of hours in acetone and even in xylene didn’t do anything noticeable. Especially xylene strips any waxes/resins and oils, even if polymerised, from metal without harming the patina. (Please be aware: that stuff has lower vapor pressure than water, so only use it outside. The smell will otherwise remain for days. Learned that the hard way). Finally I decided to gently remove the layer under the microscope with very mild polishing pastes . This also fully removed the lead corrosion from the remaining inlays, which are now nicely visible and won’t corrode any further under controlled storage. 

I also noticed that in most of the small inlay holes, only crumbled, grey, powdery residue from the former lead inlays was left. In germany this is called „Bleifraß“, translates to something like „lead rot“ (a big problem with old organ pipes and unfortunately irreversible).

Depending on its surface thickness and chemical composition, the verdigris had turned the underlying yamagane greyish, blackish, or reddish. The areas with thin and crumbly verdigris were almost unaffected.

After hours of work over a couple weeks, the brownish aubergine patina is now visible again and I’m really happy with how it turned out. The whole appearance is much clearer and sharper now. I also homogenized the rougher and more pitted areas to better match the soft sheen and reflective properties of the areas in better condition. 

I’m hesitant to go any further on the seppa-dai area— for now, I’ll leave it as is.

The shakudo of the fukurin is of solid quality. There are some old scratches and dings that show natural repatination, the “self-healing” effect.

The surface is stable now and the hazy layer didn’t come back.

The latest photos show the piece unoiled/unwaxed and completely dry.

 

 

[JohnTo]

Hi Simon,

Nice cleaning job to remove the verdigris.  I notice that the patina on the main body and seppa dai of the tsuba is brown rather than a deep blue black.  This would indicate that the base alloy is nigurome and not shakudo.  There are several examples of nigurome tsuba in the Compton collection and Robert Haynes, who wrote the descriptions I believe, describes such tsuba as Nagoyamono (things from Nagoya).  Nigurome is described as katashirome (tin and lead) mixed with copper to form nigurome.  Once gold (3-7%) is added you get shakudo and the alloy can be patinated to blue/black rather than chocolate brown.  Lots of this type of tsuba were made to meet the demand for Goto style tsuba made in shakudo, but presumably they were cheaper.  I have a few myself and some are good quality and others not so.  I don't expect you have a XRF spectrometer to check the alloy composition.  Nor do I, but would love to do an elemental analysis on these tsuba to check if nigurome is actually the same as shakudo without the gold, or a different composition.

Nigurome tsuba often turn up in major auction houses and in Japanese dealers inventory wrongly described as shakudo.

 

Best regards, John

 

[vajo]

It looks like it has lost patination after treating. To much shiny cooper now. 

[Franco]

Quote

 

AI Overview

Learn more

Shakudo is a traditional Japanese surface-colored copper alloy known for its distinctive black or dark blue-purple color. It's typically made with a high copper content (around 90%) and a smaller amount of gold (typically 3-5%). Other trace elements like silver, arsenic, tin, lead, antimony, and iron may also be present. The characteristic color is achieved through a chemical process called patination, which creates a thin layer of colored oxides on the surface of the metal. 

 

Composition and Production:

Other Elements:

While not always intentional, other elements can be present in trace amounts, including silver, arsenic, tin, lead, antimony, and iron. 

Coloration Process:

The characteristic dark color is achieved through the niiro process, which involves applying a specific chemical solution (often copper sulfate, salt, and water) to the surface of the alloy and then heating it, creating a patina. 

Historical Production:

Early methods may have involved the use of shirome, a by-product of copper production containing iron, arsenic, and other elements, or nigurome, a pre-made mix of copper and shirome. 

Modern Production:

Modern shakudo production often omits shirome and nigurome, working directly with copper and gold, with other additives used as needed. 

Main Ingredients:

Copper and gold are the primary components, with copper usually making up the majority (75-98%) and gold varying between 2-25% (but commonly 3-5%). 

Uses and Applications:

Decorative Metalwork:

.Opens in new tab

Shakudo is widely used in decorative metalwork, especially for jewelry, tsubas (sword guards), and other ornamental items. 

Surface Finish:

.Opens in new tab

The unique color and texture of shakudo make it highly sought after for its aesthetic appeal. 

Mokume Gane:

.Opens in new tab

Shakudo can also be used in mokume gane, a Japanese art of laminated metal, where it is combined with other metals like silver and gold to create intricate designs. 

Inlays:

.Opens in new tab

Shakudo can be used as a base for inlays, where gold, silver, and copper are embedded into the darkened surface. 

Key Features and Characteristics:

Dark Color:

Shakudo is known for its dark, often blue-black, or deep purple color, which is a result of the patination process. 

Unique Texture:

The reticulation (patterning) of the patina can create a unique and visually appealing texture on the surface of the alloy. 

Variations:

The specific color and texture of shakudo can vary depending on the alloy composition and the patination process used. 

Durability:

Shakudo is a durable alloy, and the patina can provide a protective layer on the surface. 

 

 

As previously mentioned, the final result will often reveal the quality of the shakudo. It may also show the ability and skill of the restorer who may have to spend considerable amounts of time trying to come up with just the right formula to achieve the desired result. And even then, nothing is assured as the alloys used in production were simply subpar. 

[Zantetsuken]

Hi John,

thanks!

The main body / plate could be yamagane, but nigurome is an interesting guess. I can exclude shakudo and refined copper, because I have several examples of these metals. I don’t have seen nigurome before. The fukurin is 100% shakudo, not sure a shakudo fukurin was regularly combined with nigurome, whereas yamagane commonly was. 
 

Hi Chris,

 

not sure why you think that way, especially if you look at the waxed before pictures. The copper isn’t shiny, it‘s a reddish brown. It’s simply not muted anymore. The patination I removed wasn‘t original or intended. There are some black corrosion spots under the greyish layer that are now visible. That’s an irrefutable proof that this layer is result of wax/oil breakdown and / or other chemical reactions. This layer also prevented the repatination to a darker colour, that can now take place.