Anyone bury their pots to enhance patina?

[penumbra]

It might sound a bit wacky for some, but this is something I am intending to do with some of my Stone Age pots. Because I use so many metallic oxides I am really curious how burial will effect them. With this type of pot I can not see any harm being done and the possibility of enhancement.
I will probably try this with a few glazed pots too, primarily mat or satin finishes. When I start I will track it here. I am thinking of a minimum of 6 months burial and probably longer.
Anybody doing this?
Your thoughts?

 

[Pitoon]

You might find this blog post interesting.....

Does Burying a Pot in Compost Create Patina?

When he was an apprentice here Andrew Robson puzzled over guidance we hear frequently: ‘Bury a new ceramic pot in compost and in a few months you’ll see patina on it’. Well, he to…

crataegus.com

 

[penumbra]

You might find this blog post interesting.....

Does Burying a Pot in Compost Create Patina?

When he was an apprentice here Andrew Robson puzzled over guidance we hear frequently: ‘Bury a new ceramic pot in compost and in a few months you’ll see patina on it’. Well, he to…

crataegus.com

I knew I could count on you to pipe in.
I think the reaction on the Stone Age pots will be very different.

 

[Pitoon]

I knew I could count on you to pipe in.
I think the reaction on the Stone Age pots will be very different.

It's worth a try, maybe try burying a couple in different substrates for a certain amount of time. Then you can report to your buyers what substrate would work best and for how long to bury them for if any patina is created.

 

[ShadyStump]

The purpose of glaze is to endure while retaining it's color and sheen.
Hence patina is a desirable trait of a pot, and very difficult to replicate. Patina defies the glaze using time.

I do think, from what I understand of your process, that you can expect different results. Your stone age pots have a much thinner coating at a lower firing than most others, and depending on the composition of the glaze itself, may be slightly more susceptible to penetration by other elements.
I feel it's worth the experiment. I have found 100 year old stoneware jug and jar pieces while digging around old mine ruins around here that show remarkably little patina, though, so don't expect too much.

 

[rockm]

Um, I bury pots to REMOVE limescale and other unwanted deposits. The microbial action in compost and mulch CLEANS pots... Patina IS NOT a build up of dirt. It is a process of glazes being burnished by the chemical reaction with fertilizers, oils on hands, and rain. It is not a simple surface stain.

The Nakawatari pot below has patina. It has accumulated over the last 120-150 years or so from BEING USED, not being buried. There are no shortcuts to get such patina. It takes time.

 

[NaoTK]

I've spent quite a bit of time studying this phenomenon, handling antique pots and duplicating their clays and glazes.

There's a reason people point to shirokouchi and aokouchi as examples of patina on pots. Both of these glazes are very high in MgO (talc, soapstone) so when you hold them they feel silky, soapy, soft. Most antique Chinese pots are rather low-fired. The clay is very tight, heavy, and I describe it as rubbery. They thud when you tap on them. The glazes are likely fluxed with boron to allow them to mature at a lower temp, which gives it a characteristic opalescent sheen where it is thin. Boron is water soluble. All these factors make the glaze surface susceptible to weathering and pitted on a microscopic level. On the bonsai bench the organics are adhering to these surfaces. Recent experiments in patina, like Hagedorn's blog, are using modem high-fired high-silica glazes which are impervious to weathering.

 

[penumbra]

The purpose of glaze is to endure while retaining it's color and sheen.
Hence patina is a desirable trait of a pot, and very difficult to replicate. Patina defies the glaze using time.

I do think, from what I understand of your process, that you can expect different results. Your stone age pots have a much thinner coating at a lower firing than most others, and depending on the composition of the glaze itself, may be slightly more susceptible to penetration by other elements.
I feel it's worth the experiment. I have found 100 year old stoneware jug and jar pieces while digging around old mine ruins around here that show remarkably little patina, though, so don't expect too much.

I have not using glazes, I am using metallic oxides. Its apples and oranges. Many people who specialize in outdoor ceramics and sculptures use oxides because the weather nicely.
And the oxide stains are not surface stains. The are applied and soak deeply into the clay's surface. They do not sit on top of the clay like a glaze. I don't expect much reaction from a buried glazed pot unless the glass is formulated or appropriate for this sort of treatment. It is a chemical reaction I am looking for. Perhaps the word patina is not the right word but it best describes my expected outcome.
Stay tuned. It may be a year, but we shall see.

 

[penumbra]

It's worth a try, maybe try burying a couple in different substrates for a certain amount of time. Then you can report to your buyers what substrate would work best and for how long to bury them for if any patina is created.

That is a given. Some places I am considering are, heavy clay soil, compost, old wood chips, peat moss, leaf mold, and so on.

 

[sorce]

The stuff I dig up by the river, which I estimate buried somewhere around the creation of the Brookfield Zoo in 1934, are all clean as a whistle.

I believe most in the handling.

If we treated bonsai pots like a teenage boy treats his.......

Nevermind.

Best stick with time I reckon!

Sorce

 

[penumbra]

Um, I bury pots to REMOVE limescale and other unwanted deposits. The microbial action in compost and mulch CLEANS pots... Patina IS NOT a build up of dirt. It is a process of glazes being burnished by the chemical reaction with fertilizers, oils on hands, and rain. It is not a simple surface stain.

The Nakawatari pot below has patina. It has accumulated over the last 120-150 years or so from BEING USED, not being buried. There are no shortcuts to get such patina. It takes time.

Understood. Read my reply above.

 

[Wires_Guy_wires]

So you want more weathering and oxidation?
Treat with freshly prepared KMnO solution as a spray and some H2O2 afterwards. Both are strong oxidizers and their effect is comparable to a couple years in the outdoors. KMnO breaks down rapidly because it reacts with everything except boron glass and some plastics. It's used to produce somewhat potable water in survival situations.
If you want, chlorine bleach will do the trick too. It turns copper shiny, and later flakey green. Chlorine is almost never easy on metals. But it can soak into untreated clay, so soaking/washing it out will be needed.

 

[penumbra]

So you want more weathering and oxidation?
Treat with freshly prepared KMnO solution as a spray and some H2O2 afterwards. Both are strong oxidizers and their effect is comparable to a couple years in the outdoors. KMnO breaks down rapidly because it reacts with everything except boron glass and some plastics. It's used to produce somewhat potable water in survival situations.
If you want, chlorine bleach will do the trick too. It turns copper shiny, and later flakey green. Chlorine is almost never easy on metals. But it can soak into untreated clay, so soaking/washing it out will be needed.

I know of several artists that work with these caustic materials to great advantage. I have seen and still own stunning copper patina art. As a potter, with some years of experience with raku and pit firing, there are many tricks to the trade I have seen and experienced. And to some results, especially those who do copper patina art, there is a certain amount of predictability, and that is great in those circumstances. I do not want that kind of control. Like raku and pit firing, I rather would guide the piece in a general direction and leave the rest to happenstance.
I didn't realize that my use of the word patina was going to reactive.
I think you pretty much have to be a potter to fully understand this.
Hypothetically, lets say you see 2 pots that you really like (and you may not). They have a rocky finish and are stone colored in various ways with subtle stains and discolorations.
Pot number one, says the potter, was sprayed with chemicals and strong oxidizers to achieve the look.
Pot number two, says the potter, was treated with natural metallic oxides and stains and buried in the earth for some time.
Now we have no way of knowing what these 2 pots look like in this hypothetical scenario, but let us assume that they are both pleasing to us in appearance. Neither way is the wrong way and certainly both can be appreciated equally, but........
Which would you get?
One size does not fit all..........

 

[Wires_Guy_wires]

I know of several artists that work with these caustic materials to great advantage. I have seen and still own stunning copper patina art. As a potter, with some years of experience with raku and pit firing, there are many tricks to the trade I have seen and experienced. And to some results, especially those who do copper patina art, there is a certain amount of predictability, and that is great in those circumstances. I do not want that kind of control. Like raku and pit firing, I rather would guide the piece in a general direction and leave the rest to happenstance.
I didn't realize that my use of the word patina was going to reactive.
I think you pretty much have to be a potter to fully understand this.
Hypothetically, lets say you see 2 pots that you really like (and you may not). They have a rocky finish and are stone colored in various ways with subtle stains and discolorations.
Pot number one, says the potter, was sprayed with chemicals and strong oxidizers to achieve the look.
Pot number two, says the potter, was treated with natural metallic oxides and stains and buried in the earth for some time.
Now we have no way of knowing what these 2 pots look like in this hypothetical scenario, but let us assume that they are both pleasing to us in appearance. Neither way is the wrong way and certainly both can be appreciated equally, but........
Which would you get?
One size does not fit all..........

I would get the one that I liked the most. If they look anything like the pots I've seen you make, I'll have both. I have enough sticks to do a reverse pairing.

I'm a pretty straight forward person in all senses: if it looks good, tastes good, smells good, feels good or it just serves a much needed function, I'm game.

The materials I mentioned, were the ones I'd use instead of burying them. After the pots are finished. I've treated concrete with acetic acid and KMnO and it produced small pores that quickly filled up with algae. Unfortunately, I suck at pottery and it turned out to be a crappy pot. But nonetheless, chemically degrading something can speed up a "patina" process unexpectedly and quite fast. I'm a big fan of raku works, my mom used to make them when she was still alive and her ceramics are some truly awesome works of mixed techniques and materials.

 

[Lorax7]

I doubt burying a pot will do much to alter the glaze, unless there was a reducing environment in the kiln instead of an oxidative environment and there are no components (silicates, aluminum compounds) in the glaze that vitrify and form a protective coating that shields the metals/metal oxides from contact with the surface. I'd expect that the majority of what constitutes patina on a pot is composed of layer upon layer of polymerized oils from the skin of people handling the pot, the thin layers of oil applied to the pot when preparing bonsai for a show, etc.

 

[penumbra]

I doubt burying a pot will do much to alter the glaze

I am not using glaze. I am using raw metallic oxides. Of course there will be a reaction but I don't know how much or how long it might take.
It was my mistake using the term patina. Bonsai people seem to have a very definite pre-concieved idea of what that term means. It is a broader term in antique and a much broader term in the art world.

 

[penumbra]

Please read my original post. This discussion has devolved into a discussion about how well glazes hold up and nothing to do with burial effects on metallic oxides and to a lesser extent on mat glazes that have a lot of metallic oxides like copper, iron and so forth.
It is obvious to all, especially to a potter, that glazed pots will have a minimal reaction to being buried unless buried for an awfully long time.

 

[ShadyStump]

Please read my original post. This discussion has devolved into a discussion about how well glazes hold up and nothing to do with burial effects on metallic oxides and to a lesser extent on mat glazes that have a lot of metallic oxides like copper, iron and so forth.
It is obvious to all, especially to a potter, that glazed pots will have a minimal reaction to being buried unless buried for an awfully long time.

To be fair...
I really don't know much about pottery, and many here don't. I think that's the nature of what we're seeing.

I've already learned some new info here, and if others read through the whole thread they will, too, and we'll all have a more productive conversation.

 

[Lorax7]

I am not using glaze. I am using raw metallic oxides. Of course there will be a reaction but I don't know how much or how long it might take.
It was my mistake using the term patina. Bonsai people seem to have a very definite pre-concieved idea of what that term means. It is a broader term in antique and a much broader term in the art world.

I’m not a potter. I’m not using the word ‘glaze’ in a technical manner, just generically to denote a surface coating: the same way you’d use ‘glaze’ to describe the sugar on a donut.

What I said about the chemistry is inclusive of raw metal oxides. You’re only going to get a change in oxidation state if the metal oxide coating is in a lower oxidative state after having been fired in the kiln, prior to being buried. If the environment in the kiln was oxidative, it’s hot enough that it would’ve driven oxidation reactions to completion. So, using the example of iron oxide, if it’s yellow/brown/red, maybe something interesting will happen when you bury the pot. If it’s already black iron oxide, burying it should do nothing.

 

[penumbra]

I’m not a potter. I’m not using the word ‘glaze’ in a technical manner, just generically to denote a surface coating: the same way you’d use ‘glaze’ to describe the sugar on a donut.

What I said about the chemistry is inclusive of raw metal oxides. You’re only going to get a change in oxidation state if the metal oxide coating is in a lower oxidative state after having been fired in the kiln, prior to being buried. If the environment in the kiln was oxidative, it’s hot enough that it would’ve driven oxidation reactions to completion. So, using the example of iron oxide, if it’s yellow/brown/red, maybe something interesting will happen when you bury the pot. If it’s already black iron oxide, burying it should do nothing.

This is true pertaining to the iron oxides though even the iron oxides are quite varied. I just obtained 9 different shades to experiment with from greens, through yellows to oranges and reds. Black is the least interesting to me and the least reactive. I am actually more interested in the reactions of copper, cobalt, manganese and rutile which I am using now and exploring others I have not used. Copper is the most reactive that I have used and from my raku experience I have seen that a copper mat finish, which can produce blue, purple, yellow, red, orange, green and colors I can't even name, will alter over time just through atmospheric conditions like humidity. I am going to play with it and show my results here. As soon as I have a few pieces to work with (having sold just about everything) , I will show some pictures now and later in the same fashion as many track their bonsai development.
There are a lot of potters here so I thought there might be more thoughts regarding oxide use in ways that are not necessarily traditional.
Thank you for your comments everyone.