Old Red Gold Patina

Darcy · May 27, 2016

OK. Bear with me. I am going to try to stab something in the heart and I am not sufficiently leveled up. I have dagger with 1d4 damage and maybe 1.5 attacks per round. I know I am out of my normal area of expertise but this is something that keeps coming up.

Gold does not patinate. This is why King Tut's beautiful gold mask survives until now. This is why gold artifacts that we uncover all the time are still gold. You can do two things: make it dirty, or you can make it rough.

Gold like swords, when you polish it you increase the reflectivity until it approaches a mirror. The more you do this the more of the color is lost if a light is shining into it and into your eyes and you see more of the environment coming in. Make it enough of a mirror and it will be. But at the right angles the color will be deep. Somewhere something else is not going to be putting its image through the mirror. Normally the metal is absorbing wavelengths in the blue and and some green and reflecting red. This mix of color, of green and red is interpreted as our eyes as yellow.

From a human standpoint we can see 3 colors: red, blue and green. We know because we cut up human eyes and we can see the receptors. We use this every day, you sit in front of your computer and you look at these nice white pixels in the backgound.

I took pictures of six pixels with a super high powered lens and this is what you're looking at:

That's white. Six pixels in fact on an all white screen. Each one of those circuits is 0.005cm wide. Pixels are made up of three sub pixels. One for each real color. From far enough back the light mixes and you just get the same receptor tickled by al three tiny circuits and your brain goes "ah this is white."

So what you see when you see gold is basically a metal with a blue absorption and red and green reflection. When we surpress the color blue your eye reacts having two out of three receptors tickled and the brain goes "Oh, I call that yellow when we see this configuration of receptors being tickled."

So, yellow isn't what I call "real" any more than white is "real" once we break it down, white's an illusion in the brain when you tickle all three color sensors just right. Yellow is an illusion, a mix of green and blue in our receptors. This may be a digression though.

OK, now .... one of the reasons we like gold is that it reacts with almost nothing. Patina is a chemical reaction of sorts. Iron forms oxides which make a patina. Silver forms sulfites and oxides and makes its black patina. Japanese experimented with chemicals and combinations of alloys to get different colors, hence we get shakudo and shibuichi as the reactions produce nice colors for art that are reasonably stable.

Gold just don't react on its own. If you want to make gold "red" what you need to do is to turn the green off. There isn't any real way to make gold stop reflecting green. So you basically have to treat it with something, because it won't react on its own. You have to somehow paint it.

The fact that it never changes otherwise is why we love gold everything. It's permanent. Unless it's been doped with a lot of other elements.

...

What I got with kodogu always was that people had referenced this gold patina, this showing up on nice old pieces and confirming their age because ... patina!

But, you don't just leave a chunk of 22kt gold out there and expect it to turn red the way silver will turn black. This is why gold has been so precious forever. It's unalterable except with very powerful chemicals which will dissolve it. You can dunk it in sulfuric acid and it will be happy. Dump in nitric, it will be happy, dump in 50/50 and you will finally dissolve it.

Back to us, we get this impression again about gold patinating to get this red color which never made sense to me. I found this in Mosle's speech to the Japan society:

In my collection is a mitokoro-mono of

Yujo, certified by Mitsutaka (Yenjo) on the kogai and kozuka, and also by an orikami. Evidently the

kogai and kozuka are by Mitsutaka with the old ornaments of Yujo fixed on them. The colour of the

gold is different from the colour of the usual gold ornaments of Yujo, and it seems that Mitsutaka

gave them an artificial colour (probably by means of a pickling solution) to produce a more reddish

gold colour, which was the fashion in his time. The ornaments are dragons {kurikara-ryo).

So here he has Mitsutaka the 13th head dummying up some first generation Yujo menuki to have a "current, hip" look. This current hip look is an artificial treatment added on later, during this time, where there was a fad for red looking gold. We are undergoing our own fad right now as men are getting pink gold watches and there are pink gold phones and computers. This kind of red or pink gold is made in the case of real gold by adding in excess amounts of copper.

Pickling away silver in a gold alloy may make the rest be deeper and if you have copper in there you can get a red-gold result. But high carat gold like Yujo probably used doesn't have enough silver to pickle it away. I don't think that is the right tack. And also if he did this it wouldn't wear so easily I think as what would be left are copper and gold and somewhat wear resistant. Better than gold anyway. So I think this is some kind of application. Or fire scaling to bring the copper up and oxidize it.

So whatever Mitsutaka has come up with is some kind of treatment, or maybe a binder and he's basically painted this stuff in place.

What I am driving at here is a few things:

1. this red gold is not gold patinating on its own, forget that, if the gold was good quality it should be the same now as it was 500 years ago if it didn't get dirty, unlike iron which will rust and patinate if cared for

2. this "red gold" look is not even traditional going back past the 13th or so Goto generation, and Mosle has caught him adding it to older Goto elements. This means that the fad to get this done gave Mitsutaka extra work on existing antique items to add this treatment.

3. it rubs off quite easily revealing the base metal.

The only thing that this is "correct" for is a trend around the time of Goto Mitsutaka for making this kind of reddish look to the gold. The trend does not last but since he apparently treated older Goto works it's mistaken for some kind of natural part of the aging process.

Now, there is naturally going to be some gunk and scratches and some of this does add to the antique look. In furniture making (I have some experience in goldsmithing and furniture making but I am not at the depth of experience as a couple on this forum, obviously Ford in goldsmithing) but if you do some antiquing of furniture to make it look older you're rubbing stain into the crevices amongst other things. The idea probably that the surface takes more wear so you're trying to create some contrast.

And we see that in these examples. Not that they were made to look older but that whatever this red application was that they put on didn't adhere well and the highest areas tended to come off with some wear.

I have some good photos recently of good Goto work and I listed it oldest to newest. The oldest is 4th to 6th generation Goto from Momoyama and these are quite evidently red now. This is the kind of thing that Mitsutaka was treating during the trend period according to Mosle who picked it up from other Japanese experts of the day. So these are from around 1570 or so.

After this is Goto Teijo as it should look. There is some color variation because of flash and environment and different times these things were taken, some in studio, some with me using a handheld camera and a flash. I had to shift this one to try to bring it back into synch with the others.

The third are the Goto Teijo that went onto my Yoshimitsu and they had some purple staining along the bellies. Not sure if that was intentional or them coming into contact with something that left a residue. But this is not gold patinating. Gold needs to react with something to make a patina. Iron reacts with oxygen, silver reacts with sulfer and oxygen. Gold reacts with dick all. The two Teijo are around 1650.

These that come after have no papers and they are on a koshirae so I had to cut the same out and I did a dirty job. The work looks nice and I think they would either go something like "Goto" or "Waki Goto" or "Kyo Kinko" if submitted. Carving looks OK but the metal is quite silvery where it's been brightened by rubbing and you can see that it has the red coat of whatever in the deeper areas.

First I'm going to display them a bit smaller to make the colors a bit more clear. Top is quite red, bottom feels a bit pink because the bright rubbed areas contrast with the reddish-yellow treatment underneath.

Click and get the super high res. You can actually enjoy the carving quite well. Still amazing what these guys were capable of doing.

Even in the Momoyama Goto piece you can see the same pattern where the treatment was exposed to hands it easily rubbed off making all the high spots reflective and yellow. Now, these things are no longer constantly being rubbed by hands. In which case if they were tsuba they would just repatinate. As any other metal would. But these will stay here forever because this is not some kind of gold rust. This is because they are an applied treatment I believe, strongly, from the middle Edo as has been pointed out by Mosle. If it's not right for the era it's probably something that should be removed.

Last thing to do is to compare the fineness of carving between the Momoyama Goto and the Teijo work. Since the details are basically painted over in the Momoyama piece it can't be shown in its true glory. In the end this is what I think it is.

My last point to prove that is that it's really globbed into the crevices. All areas that can't be reached by fingers should be evenly patinated if this was the case. Because a patina would grow from the surface and out and once the surface is covered it should stop because access to the magic air chemical which reacts with gold would be cut off. It's thicker in the crevices because that's where the brush will tend to gloop it in.

Now the final nail is that Natsuo treated my Natsuo menuki a bit the same way, but his goal was to create some depth it seems between the undersides of the waves and the shiny foamy breakers. Similar to the way the paintings were done. Dark seas with white breakers. He's goto trained and it's the same color and just runs in the areas that he wants.

What I wanted to reject always was that Gold was somehow aging and patinating into this red surface and it's just not the case for gold. The color will only changed based on the finish, whether it gets scratched up or not. But gold doesn't rot.

Now, I may have just gone and _ _ _ 's this whole thing up, insert initials that you think appropriate.

This is not so much proof as what I know from my past in casting gold and fabricating things in gold, silver platinum and palladium. I can hand fab and I was 3d printing back when we called it rapid prototyping. Whenever we were asked what rapid prototyping was, we explained imagine you had a printer, except that it worked in three dimensions. And then the marketing people I guess ran with 3d printer. Anyway....

I'm willing to be corrected based on science and proof that gold reacts to make a film which is easily rubbed off by fingers. Some gold alloys will patinate of course and you can make fire scale on gold by heating it if there is enough copper. This is another possibility for this treatment.

Interested in hearing other opinions on what you think it is.

If I'm right though it means that this is crap that was done to older Goto work 10+ generations after it was made and it's something that should be rectified when found.

Also any opinions on who made the final Shishi in this set is appreciated as there are probably hallmarks you guys recognize that I don't. No papers and I probably won't be sending them in for papers. They are on the koshirae for my Hasebe tanto and any ideas given will help me advise whomever ends up with it. I would be safer and say Kyo Kinko myself but I think they are a bit more intricately carved for a pretender. I just don't know, the head and tail look right, the body seems a bit different. Lots of details in there though so I just think it's not crap. The material might not be high carat gold though. Same redding treament, maybe makes it from the same era as Mitsutaka whomever made it. It was "in trend".

Also be warned the high res is big: 4,400 x 6,400 pixels.

High res: http://nihonto.ca/menuki-treatment-l.jpg

John A Stuart · May 27, 2016

The acids would be nitric and hydrochloric, aqua regia, no? As to colour, is that not mostly dependent on the base metal and not a surface treatment? I suspect there can be some treatment that patinates as a result of the interaction of the base metal in the alloy, and slightly due to the low %age. Not my area, so conjecture. John

Gasam · May 27, 2016

Heya,

One of my hobbies is metal detection. Old processed gold is sometimes found in my area, on account of viking activity hereabouts. For instance they used (and i suspect other cultures as well) what we call payment rings. Spiraled up thick-ish wire of gold put on fingers and suitable chunks cut off to pay for whatever you were buying.

They are found sometimes, (alas never by me it seems), but they are never patinated in any way that I have seen or heard of, certainly not red-ish. Sometimes a bit dirty looking, but thats about it. So you are right, it must be another property that patinates it somehow.

But gold can change color no? If you drop it in quicksilver, or so I heard as a kid. The jewellers here will know if that is true.

brannow · May 27, 2016

Darcy,

There is a term for reddish orange color on these fittings. The Japanese call it kin sabi (gold rust) and from what I understand it happens on older gold fittings. Its not something you would want to clean and it can be achieved artificially.

Ian · May 27, 2016

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Posted 03 October 2015 - 09:58 AM

Kin sabi (gold rust) has long been belived to be an indicator of age on things like menuki. However this is not the whole story. The effect is in fact an artificial one and quite easily applied. The process is explained in 'The Craft of the Japanese Sword' as used by habaki-shi Hiroshi Miyajima.

It's described as restoring the original pure gold colour to the gold alloy being used. And while the ingredients do leach out the non-gold elements from the surface, thereby creating an enriched skin, it also leaves behind traces of copper salts. It's these copper salts that we recognise as 'gold rust'. Other recipes omit the copper so will enrich the gold surface without leaving that red tinge.

The mixtures typically contain things like salt, saltpetre, ammonium chloride, frankincense and copper sulphate.

I think the important thing to remember is that gold is rarely used in its pure state, particularly when the whole object is to be gold. Generally speaking Japanese craftsmen alloyed their gold only with silver. Copper addditions are rare and when present very small. It would appear, from analyses, that gold coinage was often simply re-melted for use in studios. The debasement of the gold coinage was a feature of Edo period economics. Any amount of silver might then further added to create more alloy to work with. The appearance of a richer gold would then be recreated once the piece was finished. This surface enrichment, being quite superficial, wears away over time. This is why we see many gold menuki that are quite pale. It's unlikely they left the shop looking that insipid 'back in the day'. There is also class of gold alloy called ao-kin (green gold), with up to about 20% silver added, these have a distinct lime yellow tone which you will have seen in contrast to pure gold on pieces with fine inlay work. Where menuki appear more pale than ao-kin it follows that more tahn 20% silver is in the alloy. It can be as high as 40 or even 50% and still be treated to look like pure gold on the outside.

Gold and silver was also bought from official Shogunate appointed guilds, called Za in Japanese. Gold from the Kinza, which was run by the Goto and silver from the Ginza. And yes, that Ginza was in Ginza in Tokyo. :-) These guilds were first established by Hideyoshi and continued by Ieyasu.

Ford Hallam · May 27, 2016

Cheers Ian, saved me the trouble

And I very much doubt that these sorts of processes were the sole preserve of the Goto nor that Mitsutaka came up with the process. Surface enhancements of gold alloys have been part and parcel of the goldsmith's profession from day one. There are even records of such processes dating back to the 8th century in Japan.

Ford Hallam · May 27, 2016

A few more observations, now that I've had my first cuppa...

...this "red gold" look is not even traditional going back past the 13th or so Goto generation, and Mosle has caught him adding it to older Goto elements. This means that the fad to get this done gave Mitsutaka extra work on existing antique items to add this treatment.

Mosle and the experts he's advised by don't offer any evidence for their claims regarding Mitsutaka's nefarious activities. This is simply guesswork on their part. Any extrapolation based on that source is merely further clouding the issue unnecessarily I think.

It's, of course, possible that Mitsutake did alter the surface colour of Yujo pieces to follow the fashion. But to verify that we'd need first to find evidence that there was in fact such a fashion. Can we point to contemporary documents where such a taste is described?

Or is this merely post hoc 'reasoning' on the part of Mosele and his Japanese experts? And to be really thorough we ought to ask, what is the actual evidence that those pieces, signed much later with attributed mei to Jujo, were in fact made by him at all?

I might argue, with real literary evidence, that pieces attributed by later Goto masters to the first three are quite possibly 'inventions' created to emphasise the historical legitimacy of the house of Goto as part of the Shogunate's authority.

There was, in fact, something of a mad rush at the start of the 17th century, by Iemoto schools in all of the various arts, to invent older hereditary lineages with which to secure their place in the new Tokugawa controlled society where the age of an institution equated to authority and legitimacy. This is well documented in a number of scholarly works. The fact that the early history of the Goto family is generally unchallenged may have more to do with their use to the Shogunate as the managers of the mint and overseers of fiscal policy (often quite disastrously) and their role in creating an impression of an unchanging status quo.

Darcy · May 27, 2016

The acids would be nitric and hydrochloric, aqua regia, no? As to colour, is that not mostly dependent on the base metal and not a surface treatment? I suspect there can be some treatment that patinates as a result of the interaction of the base metal in the alloy, and slightly due to the low %age. Not my area, so conjecture. John

Aqua Regia would dissolve the gold (hence the name, Water of Kings, the only thing that gold will dissolve into). It would ruin any surfaces it comes into contact with.

Pure gold is a deep yellow, we know it from good fittings and Asian culture sees it all the time. Western doesn't because going for cheap jewelry tricked America into thinking that 10kt (42%) and 14kt gold (58%) were "gold". European culture is more 18kt (75%), and Asian tends to frown on any gold that is not pure.

Alloying gold, generally you will mix in silver and then copper, the two metals cancel each other out a bit in terms of color but it will make ever paler gold, until it starts looking brassy. If you overweight with silver the color looks greenish, and we call it "green gold" (yeah, saw that coming). Overweight with copper and you get "pink gold."

If instead you alloy gold with nickel it rapidly loses all color and you get "white gold". White gold came about when platinum was discovered and became popular, so white gold became a poor man's platinum. Now we know nickel and skin is not a good combination o palladium can be used (which for a long time caused the value of the alloy to increase as palladium was mostly more expensive than gold).

Platinum needs no alloying, but is sometimes 10% iridium or 5% ruthenium. Those two metals are very hard and so you get a 900 or 950 platinum for jewelry use. Digression on the way here.

So if you take something that is a low karat gold like 14 karat and you attack the surface with a strong acid you can pull out the copper or the silver. Think of it kind of as a reverse plating. This makes the gold that's left over and whatever other alloying element if one of them was left, take over and the color deepens. But it is subject to wear, it's just atoms deep.

You would heat the gold somewhat and go at it with nitric acid.

This is all 20 year old knowledge from when I did this for fun and I am out of date. Ford will know this inside and out.

But if you went up against a Yujo with aqua regia you would very likely harm the details as it's going to attack everything. Gold, silver and copper.

Last note is that gold was what you could find and refine and you'd never get pure pure gold like we have today.

Darcy · May 27, 2016

Darcy,

There is a term for reddish orange color on these fittings. The Japanese call it kin sabi (gold rust) and from what I understand it happens on older gold fittings. Its not something you would want to clean and it can be achieved artificially.

Bill, that's my whole point. There is no such thing as gold rust.

If there were, we have an ex science teacher waiting in the wings and I also did chem in university. We'd like to see the atomic formula for "gold rust".

What we have though is a 100 year old testament from Mosle saying that Goto Mitsutaka was treating these things to make them look like this. This means he was modifying them to look in ways they should not. That's what we have today... "gold rust"... with no atomic formula.

Gold does not react with anything. This property is why Gold has always been precious. Silver is not as precious as gold because Silver reacts with sulfur and oxygen naturally which are in the air. Copper reacts with oxygen. Iron reacts with oxygen. Anything that "rusts" is reacting mostly with oxygen. Gold reacts with neither.

When they cracked open Tuts tomb, it looked like that. If Gold was just another metal that rusted out then it would be no different from copper in the grand scheme of things.

So my point here is that nobody has ever explained "gold rust" scientifically and any scientist will tell you "gold rust" does not exist. Now in my digging I see Mosle remarking (and he was taught by some experts in this) that Mitsutaka did a trendy adjustment to old work to bring them up to date with the fad for red gold during his time.

Mitsutaka is an important guy. He did a LOT of the attributions on older stuff which became Juyo now. So he touched all the old masters. This means he may have updated a lot of the old masters. In fact people may have been bringing him stuff saying make this up to date, and attribute it while you're at it.

Now: ask yourself about other patinas.

If you rub them off, do they stay off? No they come back. Because they react with what's in the air. What in the air is reacting with gold? There is nothing in our atmosphere that does this.

All of these treatments rub off. look at my examples, even the heaviest is still showing signs of being rubbed off. It won't ever change.

This is because it's not a natural thing. 'Gold rust' is an applied technique of Goto Mitsutaka to "modernize" old work. After this it is a technique in the toolbag if someone wants to create red tones out of yellow the way Natsuo worked with it.

But Gold Rust doesn't exist. It's not a scientific thing. If someone took a sword and painted it blue because this was a trend eventually we would undo that and put things back to the way we hoped they were when made. We call that restoration. Changing the fundamental appearance of old Goto fittings to fit Mitsutaka's time was not restoring and was not repairing. It was "updating".

When they do this with paintings, inevitably it needs to be repaired and brought back down to what it was when the man made the painting.

Yojo's work, according to Mosle, does not have this red color. If Mitsutaka attributed it, maybe now it will have the red color because Mitsutaka painted it on. This is graffiti. So if we want to restore it, we first need to undo the "trend" crap that was done to it and return it to how Yujo made it.

I am seeing evidence of this stuff for sure. And I think this "gold rust" is coming from a place of not knowing chemistry. And not getting the info that Mosle got.

I am 100% open minded and I am very willing to believe in "gold rust".

Just tap the chemcial formula in here: _______________________________ and me and Barry will get to work on it.

Maybe Barry I can bring those red Muromachi dragons. If you still have access to some mad scientist stuff, let's break down what this stuff is. I am very, very curious. I have a good example and we could actually figure this out.

Darcy · May 27, 2016

A few more observations, now that I've had my first cuppa...

Mosle and the experts he's advised by don't offer any evidence for their claims regarding Mitsutaka's nefarious activities. This is simply guesswork on their part. Any extrapolation based on that source is merely further clouding the issue unnecessarily I think.

It's, of course, possible that Mitsutake did alter the surface colour of Yujo pieces to follow the fashion. But to verify that we'd need first to find evidence that there was in fact such a fashion. Can we point to contemporary documents where such a taste is described?

Or is this merely post hoc 'reasoning' on the part of Mosele and his Japanese experts? And to be really thorough we ought to ask, what is the actual evidence that those pieces, signed much later with attributed mei to Jujo, were in fact made by him at all?

This is the thing with experts. I assume he has more info than me. If he throws off "this was a fad in his time" then I'd suppose as a serious guy he's not just throwing it out there. This may have been common knowledge at his time.

The ultimate though is that we know from science Gold does not Rust. So whatever is on these, this is a treatment. Natsuo use it cleverly in my menuki to enhance the color shifting and the shadows.

Anyone who can tell me it is gold rust has to write down the atomic formula. Because we know gold does not rust.

So then I am setting up two parallel scenarios:

1. Gold rusts.

2. So all gold should rust.

3. The older it is the more rusty it gets

But we don't see it in the lab or anywhere else where Tut's mask did not rust. Old roman coins did not rust. Gold sculptures don't rust.

Now this is the responsibility of those making the claim " gold rust " they are trying to introduce a new compound into the world. Then, the rest of the world, on a science basis, should say:

1. identifiy the compound that is gold rust

2. give us a reaction that produces gold rust

3. show us cases at room temperature where this reaction is valid

This is supposed to be a room temperature reaction that just happens. But none of the three critical things have explanations behind them.

We call this "rubbish" in science if you have to handwave over them.

Whatever has been done is a reddish compound rubbed on the gold. When it is rubbed on it obscures the details. After cleaning the details are revealed undamaged.

This is a surface treatement to tint existing stuff from what I see here.

I am not relying on Mosle as fact. I have had this problem from day one that the only people in the world who believe that gold rusts are nihonto kodogu collectors.

So this is acutally the group with the extraorindary claim that gold rusts. The proof needs to come from them.

What I see is this:

1. Kodogu styles and koshirae styles changed trough the years

2. People wanted to bring their old stuff up to date (since suriage basicaly).

3. Likely menuki were wanted to come up to date.

4. So, apply a finish and you have up to date stuff.

It's like painting a house, you keep the structure but you change the look for the latest trend. I don't see a reason to disbelieve Mosle when he relays the fact that this gold look was a fad at Mitsutaka's time and he is relaying that Yujo's stuff never looked like that when it was preserved.

My own conclusion is just that this stuff was xxxxed with. Now we still do it. Guys are carving hi in antique swords because they like it. Changing polish because they like it. Nobody is going back to try to make it how it used to be so much.

Firmly: I want the chemical formula for "Gold Rust." If someone wants to claim this exists, they need to say what it is. Determining what it is will tell us how it can come to be and this answers the question if it is a later period treatment to modernize old works, or if it is something legit and natural.

I know how that's going to go. I've worked with gold. This is something that needs adjustment I think in the way people think about it.

Darcy · May 27, 2016

Now the final thing, I am 100% certain it's a treatment. Micro photography reveals it to ruin the surface with a coating of crap. If you remove it you see the smiths' original work. If you remove it the flat earth guys of today will reject it. "Needs gold rust!" which in my opinion is just some mix by Mitsutaka to put on old things.

So, if you do remove it then you piss off the old Japanese scholars and maybe devalue your piece but it's a vote for the truth.

I want to take some of this stuff and send it in for assay to see what it is.

I don't think there is any gold in gold rust. If there isn't, then it means that there is no reaction with the surface and it's just crap laid on top.

I need a university metallury department to figure this out.

I just know from my own experience that there ain't no such thing as AuO2 and if there's gold rust someone better describe the molecule.

Ford Hallam · May 28, 2016

Darcy, methinks you're trying too hard to find a problem. Kin-sabi is/was very obviously, historically speaking, a poetic/metaphoric description of an artificially induced effect that pre-dates modern scientific analysis. I don't think this poetic term literally implied gold was rusting any more than Ro-gin meant that silver was getting cloudy like the moon or karasugane really was an alloy made from bits of crow. Some contextual understanding of Japanese metalworking culture may be useful.

I've described the method and typical mixtures used. This is not a mystery for traditionally trained metalworkers in Japan....well, at least the older ones

Now the final thing, I am 100% certain it's a treatment.

yup, on this we're agreed...I did try to make that clear in my post that Ian helpfully quoted.

Now this is the responsibility of those making the claim " gold rust " they are trying to introduce a new compound into the world. Then, the rest of the world, on a science basis, should say:

1. identifiy the compound that is gold rust

2. give us a reaction that produces gold rust

3. show us cases at room temperature where this reaction is valid

This is supposed to be a room temperature reaction that just happens. But none of the three critical things have explanations behind them.

and I'm sorry but I can't help but reply to this...

1 and 2 are fine but why the insistence on room temperature in no:3?

This is an assumption not worthy of a serious scientific examination. By demanding that this process take place at room temperature you're imposing a limitation of your own imagining not any actual evidence. Why do you insist kin-sabi happen at room temperature, especially as I've already described it as an artificially induced effect?

The ultimate though is that we know from science Gold does not Rust.

But the truth is gold can and does oxidise, or 'rust'

This is from wikipedia only because I can't be asked to scan or type in pages of reference books from my library. This oxide is in fact present in kin-sabi so the scientific, goldsmith approved, reality is that kin-sabi can actually contain real 'gold rust'. Work by Prof. Ryu Murakami has demonstrated this point, it's all in Japanese but I'm getting translations done and hope to publish much of his work at some point.

Gold(III) oxide (Au₂O₃) is the most stable oxide of gold. It is a red-brown, thermally unstable solid that decomposes at 160 °C.^[2]

more here;

https://www.americanelements.com/gold-oxide-1303-58-8

there's the gold rust molecule

I just know from my own experience that there ain't no such thing as AuO2 and if there's gold rust someone better describe the molecule.

...ok, challenge accepted. To see AuO2 try here

http://www.chemspider.com/Chemical-Structure.26944210.html

Ford Hallam · May 29, 2016

Darcy

looking through the various recipes recorded in Natsuo's workshop note books for kinsabi and playing with them yesterday I rather suspect the film on the wave menuki you had is in fact a mix of copper sulphate and kunroku, or frankincense. Frankincense crops up in a number of old recipes and in this case seems to deliver something of a varnish-like effect. Frankincense is a sort of aged plant resin.

Ken-Hawaii · June 10, 2016

But gold can change color no? If you drop it in quicksilver

Well, yeah, gold does change color if it comes in contact with mercury (quicksilver) because it forms an amalgam - what dentists used to use to fill cavities in teeth. That's pretty much a permanent thing, however, unless you heat the gold up high enough to boil off the mercury (thereby sending neurotoxic mercury vapors into the air). So not a good idea at all.

Ken

Darcy · July 1, 2016

Ford! Very good answer! Love having data. Very interesting and in agreement with what I've been thinking.

Natsuo doing it on a Natsuo piece is something to never ever touch.

I will continue my tirade against mid-Edo guys mucking up earlier work.

I am just looking at some new menuki today that arrived. Low res and high res photos. High res is at full capability of my macro lens so can show on a screen at about 10x ... microscope. First, amazing how much detail these guys did and we cannot even see without this kind of magnification. but this is another case study of the "gold rust" as this is a Ko-Mino Muromachi period menuki and was remounted in the Edo period and recently unmounted. During the Edo period someone did the kinsabi treatment on it and then it was wrapped. This treatment completely wore off on the high points between the wrap and elsewhere between the wrap to a lesser extent. Under the wrap it remained in place so we can see the different states.

If it were a natural process then exposed areas would age, not covered areas. If it is an effect applied on top, then it will wear away where exposed and stay in place where covered. And it's not on the backs. So it's not an effect of being covering. This leaves us only the Frankincense type of treatment.

This in areas looks like it was layed on thick and it pooled before hardening. It completely covers some of the dragon's scales in low areas. In other areas I can see some brushmarks.

To me now, this is bad condition because we have nice old menuki that someone messed up in middle edo and now half of their messed up stuff wore off so it is a mix of everything that can be wrong with them. If it was just old and dirty that is correct for antiques. But returning it to its state before someone messed it up is not destructive. Similarly you don't want them to become BLING like they were made yesterday. This kind of thing needs to be evened out and made to be reasonable so that it looks its age appropriately without having much of a trace of the 1700s era defacement left on it.

High res link: http://nihonto.ca/gold-rust.jpg

Photo below. The big photo above is really interesting to look at just other than the 1700s wack job on it. Very high res photo of old Muromachi work.

Darcy · July 1, 2016

What you can fab in a lab in 2016 or even in 1900 is not mimicking the process of "rust", don't conflate "oxidation" with "rusting", and even in chemistry oxidation means something different than how we use it.

The entire reason that Gold has value is traditionally it was the only thing that didn't change in the environment. Empires fell, mountains fell, rivers dried up, but the pharaoh's mask remains as it was made. This connected people to the permanent world outside of our world and for that reason gold was often treated as a holy object. Look at the churches, the native americans, the buddhists. Gold is a big deal everywhere precisely for this.

There is no get out of jail free card for Japanese menuki which somehow magically have the ability to undergo a magical unexplained process and "rust" on their own without American Chem Inc throwing their factory behind it.

The Japanese dude who claims to have Au2O3 in kinsabi, well you need to do better than just a one liner saying you saw this on wikipedia. The formulation of this compound involves:

- Perchloric acid which is stronger than Hydrocholric and will get you dead very nicely if it doesn't catch you on fire first

- Quartz flasks because the stuff you're going to be dealing with will probably melt or burn glass

- High temperatures

- Some unnamed alkali which is probably some other horrific thing that holds the gold in the first place, formed by other first world last century chemistry

- And last but not least 30MPa pressures.

All that on one line on wikipedia for google arguers to point at and conclude "gold rusts."

That is not rust.

30MPa is the equivalent pressure to 3km under the sea or 300 times atmospheric pressure. This is what is necessary to force gold to react with this very evil very horrible acid and incredible oxidizer to get gold to pick up the oxygen.

This is not an Edo period jeweler's workbench kind of process. This is not an "oops I left it in the rain in the backyard for a week and it rusted" kind of process.

1km under the sea will crush the USA's most sophisticated nuclear submarine into a tin can. Perchorlic acid will melt your eyeballs out of your head and is a precursor to rocket fuel. It's the go-to when sulfuric just won't burn someone's face off fast enough for you, or if you think nitric acid is for children, then you use a man's acid like perchloric. Which you need to heat quite high in order to get a reaction with gold.

Material handling notes: When heated to temperatures above 150° C perchloric acid becomes a strong oxidizer and eventually becomes unstable. Concentrated solutions are very dangerous and can react violently with many oxidizable substances, such as paper and wood, and can detonate. Vapors may also contaminate work surfaces or ventilation equipment with perchlorate residues, which may form highly unstable compounds, such as metallic perchlorates. These compounds may ignite or detonate under certain conditions.

This is just not reflecting the kind of chemistry that you will see in your drawer turning your menuki red. This is the kind of thing mixed with a very strong acid that is required to pull electrons from gold. And nobody wants chemicals that detonate in their workflow on a daily basis because sooner or later KABOOM. Probably sooner.

And even if an Edo guy could use some magical process not involving modern chemistry to oxidize gold, why would he?

For instance, any one of you can go and light 100 dollar bills on fire, but you don't do it. You can use other things to light your cigarettes or burn down whatever you want to burn down. But you don't use 100 dollar bills.

If you can crush a red rock and mix it with lacquer and paint it on, presto, you have "kinsabi."

These attempts to connect it to gold are just the results of cognitive dissonance. People have been told it's connected to the aging of the gold for so long and they didn't question it that it's hard to let go of. So some intermediary steps are proposed but none of it makes much sense.

Mosle is perhaps the first guy to write about these things for the west, and his sources lived in the Edo period. And they told him bang, the Goto mixed some crap and put it on these items to satisfy a trend. Somehow from there we lost that fact and it became gold patina. So this whole patina thing is not even that old, if the guys in the Edo period didn't believe it then why should we?

Outside of the immediate evidence of this being painted on stuff... already replicated by Ford, as seen in items shot at high magnification (and Japanese publications almost never do it, they love to shoot things at life size so you know what they look like in your hand... why that is useful for an 80 year old Japanese guy who needs glasses I don't get, I like to shoot it big enough that I can see the details and the details tell the story).

Lastly, anyone ever seen kinsabi on the back? Maybe. I haven't. My backs look like gold and my fronts look like someone painted purplish red crap on them under the macro lens. At arm's length to 80 year old Japanese eyes it's "gold rust". But it doesn't stick unless you cover it and real rust develops where you don't cover it.

I think the evidence is clear it is a cosmetic finish put on, Gold on its own is the most noble of metals and doesn't react with anything in the environment (yes, exceptions in the lab, we can also fuse hydrogen in the lab but it's not happening on the Edo period workbench or by leaving a glass of water on my desk for 300 years).

Contents of the cosmetic finish, again doesn't even matter because it's defacement of older work to adjust it to a new trend. If the new trend today was blue menuki and I painted mine blue because I thought it was cool, 300 years from now should someone accept that? I don't think they should even if we all agreed that blue menuki were the way to go and did it en masse.

Anything a guy like Goto Mitsutaka made red and signed, that should not be touched at all. This was his finish and his group and his period. That's authentic to them.

But they messed with old stuff and that wasn't right.

And anything trying to just cling to the idea that gold menuki rust and no other gold in the world is doing it... I mean I made a ring out of the gold from my father's fake tooth about 15 years ago. He had it in his mouth for 40 years. It never rusted then and it hasn't rusted since and I don't think even if I pretended it was a menuki it would suddenly break all the rules and turn red.

Ford Hallam · July 1, 2016

Darcy

just a few points.

You demanded to see a Gold Oxide molecule when you emphatically stated gold does not 'rust'.

I showed you the molecule. I didn't suggest it happens naturally nor that menuki would 'rust' over time.

The kinsabi process is an artificially applied cosmetic finish, on this we're agreed.

We cannot say when it became fashionable to use this process or who started it.

Gold is rarely used in a pure state in Japanese metalwork. In almost every case we find that silver has been alloyed with the gold and in some case a very small amount of copper is also present.

Various depletion gilding processes that have been in use in Japan since the 8th century use combinations of copper salts, and other oxidising salts to leach the non-gold elements out out the surface of the metal to leave what appears to be a fine (pure) gold finish. Some of these processes also leave a slight reddish 'blush' on the gold surface, presumably this is a copper oxide film. This does not wipe off like the frankincense type finish but the exact nature of the bond has not been investigated as yet. I suspect it's some sort of flash plating.

If this depletion gilding process hasn't been carried out on alloyed gold then it's perfectly possible for the non gold elements in the alloy surface to react with atmospheric pollutants, oxygen, hydrogen, sulphur etc. In this case it's perfectly accurate to regard the resulting "corrosion product' as rust. Perhaps not gold rust per se, but certainly gold alloy rust.

And even if an Edo guy could use some magical process not involving modern chemistry to oxidize gold, why would he?

The whole discussion here demonstrates that in fact they did do things to make gold look like it had rusted. We can get into a discussion about the aesthetic tastes of the era but it's self evident why they did it, they liked the look of it.

Gold was used as a metal as part of the artists palette, yes it was valued for it's preciousness but it was also manipulated in a number of ways to extend it aesthetic range. The variety of gold alloy colours being one example. So called rusting of gold or gold alloys was another way they pushed the range.

But to reiterate, we don't know when or who started this fashion.

We do know the processes were known from the very start of the metalworking tradition in Japan and played a fundamental part in gold coin production from earliest times. And as we all know that Goto were the mint masters so they certainly knew all about kinsabi and depletion gilding from time of Goto Yojo at least.

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