Lately I’ve been working on ways to bring out the crackle in my teabowls, as well as make the crackle finer (without having to use them for decades or centuries, or reformulate my glazes, so in other words: cheat).
These two bowls had big crackle ( 1cm +-) and I reheated them, then doused in cold water.
***WARNING: Ceramics generally don’t like to be heated or cooled quickly. Don’t do this if you’re going to be upset about breaking a bowl!***
For the kohiki bowl, I heated and doused once to make the crackle smaller, then reheated to open the crackle wider, and closed the damper on my stove, to get that carbon to penetrate the crackle.
Because the body and the glaze were vitrified, but the white slip in between wasn’t, spots (where the slip was thickest) on the rim separated from the body and had to be restored with lacquer and gold (*1)
The results vary, and it is high risk, but you can get an idea about how your bowl may mature over years of use, and plus it’s just fun to play around with fire…
Another common way to bring out the crackle in you ware is to boil it in a pot of strong tea for a few minutes. The tannins will then turn brown, especially if you put the piece out in the sun to dry (or any other UV light). For an even darker, quicker reaction, after the piece is dry, apply some iron acetate. The iron acetate reacts with the tannins and turns quite black over a period of 24 to 48 hours. This is actually an old woodworking technique that I applied to pottery, and it works well, in addition to being non toxic.
***Results may vary***
(*1: I didn’t use real gold for this bowl, but I would on a very nice piece. For this piece I used a brass based metal powder. For more info on this kind of repair, check out Dave Pike’s blog, or store on Etsy)
Two years ago, my supply of stable dobai 土灰 dried up. I bought up the remaining stock from the supplier, but that didn’t last long. When I switched to another source of dobai, the results were far different than what I had imagined. My two main bread and butter glazes haven’t been the same since.
Which brings me to my current predicament of having to basically start from zero and re-formulate these glazes with different ash. Fortunately, I have basic analysis info from the old ash, and also for the new types I will be testing with, so I can use glaze calculation software to calculate substitutions, which I am hoping will give me a head start.
For your daily dose of trivia, the word dobai is rendered in kanji as tsuchi 土, and hai 灰, or ‘dirt ash’ (which makes no sense to me). All other ash has a proper name, like pine ash, oak ash, fern ash, etc… I finally found a possible explanation for this odd name the other day when I was searching for ash sources on the net. Turns out the ‘do’ of dobai is actually shortened from the original name ‘kamado’, which is a large pot used for roasting, cooking, burning stuff, etc. It is easier to say dobai, than kamadobai, after all, I guess…
Here are my 3 main candidates for testing:
I picked up one kg of each, and will narrow it down to just one. They are all about 10 dollars/kg, expensive right? I make my own pine ash because I have a good source of already burned pine, but I’m not set up to process large amounts of ash, and when it is all said and done, spending 10 dollars or more per kg is cheaper than the time and sweat put into making my own ash. Rice straw ash is more expensive at almost 20 dollars per kg and it is still worth it when you take into consideration the gathering, burning, quenching, floating, stamp milling, 2nd floating, (ball milling in some cases), and drying process this ash requires.
This is an underglaze decorated madara glazed yunomi fired in the wood kiln in 2013. It was heavily reduced in the firing, resulting in the dark clay color and carbon trapping in the glaze.
It is a small yunomi, and could almost be called a large guinomi, and certainly has the character of a guinomi. People generally confuse guinomi with sakazuki (sake cups), but Guinomi are cups used for tea, sake, whiskey, etc…, that have a higher status among pots than yunomi, because they are usually one of a kind pieces, not made in large batches like yunomi usually are. Think of them as a sort of ‘mini chawan’.
I am making the distinction, because this last trip to Korea and the tea bowl festival really accented the differences between the preferred shape of a tea bowl between cultures.
The one type of bowl here that probably illustrates the point best, but of which I don’t have a good example, are the Ido chawan. We make these forms in Karatsu, but don’t refer to them as Ido Chawan. Rather, we call them Karatsu Ido, or Ido Gata Chawan. The original Ido Chawan are from Korea, and contrary to the idea that the ideal shape is like Kizaemon (below), Ido come in many shapes and sizes. I’ve even seen on Ido bowl with a warikodai (foot carved into sections).
Anyway, if you look carefully at Ido forms, two things are often noticed: One, the lip is quite sharp on the inside edge, even though the outside of the edge is rounded, and two, the interior of the bowl is not rounded but rather pointed. These characteristics seem unrelated or even impractical for tea, after all, who wants a lip that is less durable, wouldn’t a round lip be more practical? Also, a cone shaped pointed interior is not suitable for whisking tea, is it? There is no room for the whisk to move, after all.
So why did tea masters choose these bowls as paragons of ‘teabowlness’? The answer is simple. They weren’t used for whisked tea. Most tea practice revolves around usucha, or whisked thin tea, but the tea that holds the highest position in tea ceremony as an indispensible part of Chaji, the full tea ceremony, is koicha, or thick tea. Thick tea is not whisked, it is kneaded and folded slowly into a thick paste with the whisk, and the coned interior of the bowl allows for this to happen much better than a flat or rounded interior. Then when drinking this thick paste, it is much better to have a sharp interior lip in order have a clean separation from the bowl when drinking. Koicha is usually a shared bowl, and will be shared by two or more people. After drinking, you must wipe the lip and pass it along to the next person. The sharper interior lip makes both drinking and wiping an easier less messy experience. So, these two characteristics end up being optimal for tea, in the proper context of Japanese koicha.
Even more interestingly, these two characteristics were not intentionally designed by the makers with koicha in mind. They are the direct result of the clay, process, and tools used to make the bowls, which were likely made quickly in large numbers.
In Karatsu, we use cows tongue ribs to shape the clay, because it is large particle material and not very plastic. In some cases, such as porcelain stone and sandstone, it is not even clay at all. The cows tongue allows shaping by compressing the clay body, rather than stretching, like a standard rib would do. I always thought that cows tongue ribs came from Korea, but I have never seen one there during my visits. There is, however, a tool that looks a little like a mini tugboat that functions much the same way as a cows tongue. When making bowls quickly with as little wasted movement as possible, the interior of the bowl naturally becomes conical rather than rounded, and pressing the lip between finger and cows tongue naturally produces the characteristic Ido lip shape, while preventing splitting of the lip by compressing the un-plastic clay body, and also eliminates the need to use a chamois on the lip to compress or clean up.
So, I seem to have gotten off on a bit of a tangent here, but back to the main goal of simply leaving you with some images of tea bowls: