Electrically Burning Fractal Patterns Into Glaze-- Mocha Diffusion

[docweathers]

 In a discussion with Min about improving mocha diffusion she pointed out this link to me. It describes a way of doing a mocha diffusion like pattern on wood with electricity. I'm wondering if there is a way to adapt this to a kind of mocha diffusion for glazes at ^6.

 

http://makezine.com/2015/06/10/burn-fractal-patterns-plywood/

 

 

I'm thinking about building one of these things.  However, before I launch,  I would appreciate any ideas about whether it would actually work with ceramic glazes and what would be the best way of adapting it to ceramics.

 

I can get ordinary mocha diffusion to work but not at the level I would like to see it.

[neilestrick]

I'm not sure how it would work with ceramics. The process in the video is burning, which wouldn't happen with clay. I guess the question is whether or not the slip will react to the current the same way. I'm thinking there's something about the combustion and the fact that the wood itself is not all the electrically conductive and that the current peters out near the end of the patterns as the water dries up that makes this work. I'm thinking something cool could come out of trying it, I just don't think it will be the same result as the wood.

[oldlady]

larry, when do we get to see the pots you have done with mocha diffusion?  i have always liked them but not enough to try it more than the one time.  lemmee see.

[terrim8]

Yikes!!!!! water & electricity ????? Moist clay, wet slip and how many volts?????

 

Ya that watermelon with the molten aluminum was cool & likely  actually safer than all that voltage with wet slip or clay.

[oldlady]

that was a great website.  i can see why you like it, doc.  now i need to tell my daughter about it.

[What?]

Reminds me of horsehair.

[Marcia Selsor]

I think it is easier to use water and salts for achieving the mocha. It is also the way it is done painting with water colors. This is from a foil saggar pot.Some are better than others.

Marcia

[Mark C.]

And I thought mocha diffusion happened in a coffee cup?

[docweathers]

here is a link to some of the better mocha diffusion I have seen.

 

http://jovicpottery.com/mocha-ware/

 

I corresponded with Vic for a while about his technique . 

 

Here is what he said" I have, indeed, modified the ‘ body slip ‘ . From my observations, a vessel shrinks by about 6% from freshly thrown to bone-dry. ( I am currently using Plainsman M-370 which shrinks about 14% from wet to finished ).

 

If you were to apply ‘ body slip ‘ at the leather-hard state, there would be a good chance that there would be no problem since the clay and slip are shrinking together, albeit with a little tension.

 

If, however,  you were to apply ‘body slip ‘ at the bone-dry state, the thin coating of slip would have to go through the 6% shrinkage on a surface that will not shrink any further. This may result in a cracked slip surface when the vessel finally dries, or worse, after the vessel has gone through the final fire. I believe this is referred to as ‘ shelling ‘ and can be very dangerous for any neighbouring pots and the kiln, too. My earliest efforts with ‘body slip ‘ were disastrous with sharp scabs all over the surface.

 

I would suggest that you look into comparing clay body recipes with a few slip recipes, then with engobes and finally matte, then satin and glossy glazes. You will notice that progression from lots of clay  ( and a few fluxing materials )  to a relatively low amount of clay ( and a wide variety of fluxes ). You will need to experiment but with the all the resources on the Internet, I’m sure you can find a suitable slip much quicker than I did when I started Mochaware in 1981.

 

Above all, avoid the use of copper in your Mocha tea....it will bleed or over-diffuse to the point that it obliterates any evidence of dendritic growth. Use chrome oxide or commercial stains if you want green.

 

Use a steel kidney to eliminate throwing lines which would induce odd, lateral tree growth.

 

If I might suggest it, get a copy of Jeff Zamek’s ‘ What every potter should know  ‘ . I’m sure you can get it from the library. It has a good deal of info about Mocha application."

 

I have also corresponded with Robin Hopper. Here are my questions to him:

 

"I am trying to refine my skills at mocha diffusion. I have read your articles and watched your video on mocha diffusion. They are very well done.

 

Sometimes my results are fairly good and other times they are unsatisfactory. It seems like an unreliable and difficult to repeat phenomena. I have run many dozens of experiments and come up with a list of variables that I have questions about how to manage. Below I will list some of my observations and questions. I would appreciate any guidance you can offer.

 

1. I have experimented with a number of different slips including yours, G-Mix 6, and Wollastonite. They all seem to work pretty well. Wollastonite seems a bit better. Mixing these with distilled water, which I think increases their surface tension, helps a bit.

 

2. For tea I've experimented with apple cider vinegar, Worchestershire sauce, soy sauce, boiled tobacco, and propylene glycol.  The all work. Vinegar, Worchestershire sauce and tobacco are very similar, with tobacco being slightly better than the others. A little bit of Epsom salts also seems to help.

 

3. What makes the most distinct improvement in the tea is one drop of dish soap, which I think reduces it surface tension.

 

4. The surface wetness of the slip seems to be one of the most critical variables. Too wet and you get a large blurry pattern.  To dry and you get a small pattern. There seems to be a very thin line between these that is difficult to judge. This variable is so critical that it confounds my other tests. Do you have any suggestions on how to judge and manage this? I would also like to come up with a way of keeping a large area of the slip damp long enough to put many large patterns across it. With conventional procedures, you only have 10 to 15 seconds to get the tea on the slip before the surface becomes too dry to continue to spread. I'm going to experiment with a vaporizer to raise the humidity in the immediate area where I'm working.  Do you have any other ideas?

 

5. Sometimes I get small delicate flowery patterns and other times I get long simpler dendrites. I haven't figured out a reliable way to get one or the other. They both would be a lot nicer if I could control which one I get where.

 

6. A chemist friend suggested that coloring oxides could destroy the patterns.  In my simple experiments, I haven't found this. Have you found any that don't work well or any that work exceptionally well.

 

7. To apply the tea, I've tried the conventional method of using a tea loaded pointed brush and a small hypodermic needle. The latter seems to give me much better control.

 

Any other guidance would be appreciated. "

 

Here is his answer:

 

Hi Larry,

On reading your letter, it would seem that you have tried just about everything that I would have done and a whole lot more. THis is a simple process done by uneducated peasant potters for at least a couple of centuries. They likely wouldn't have any idea about the tech stuff. They didn't have time for things that weren't easy.

I would suggest that it is basically a matter of getting the viscosity right and the right amount of acid to alkali. This is CRITICAL. It is a gut reaction/ eyeball  thing, not a high tech thing. I have used MD for at least 50 years in the simple process and recipes. For the last 40 years I did workshops including MD around a lot of the globe and only once had a problem.  That was when the tech gave me a thinned-down porcelain clay instead of my requested slip recipe. I never specified any particular ball clay, kaolin, feldspar or silica, because I was often doing workshops in other countries. I have taught the process in China, Korea, Japan, Israel, Australia, New Zealand, Canada and the US with never a problem.  I'm a great believer in keeping things simple - You get far less problems that way!

The slips are applied fairly thickly. For colored "tea", only use carbonates as they are lighter in physical weight than oxides, unless there is no carbonate form of the mineral. Titanium Dioxide disperses better than Rutile. Heavier colorants will sink into the slip and not move with acid."

 

 

He also sent me the attached article.

 

 

 

 

 

 

 

Mocha Diffusions.doc

Mocha Diffusions.doc

[terrim8]

Robbin Hoppers articles are very useful. thanks for all the great info!

[Min]

Someone posted a demo on instagram--can't for the life of me find it, of someone using acetone as the "tea."  It pulled up some really wild dendrites.  Maybe Adam Field or Brendan Tang?

 

Was it this one from Kevin Kowalski? (right picture, top row he says he uses nail polish remover plus black stain)

https://www.instagram.com/kowalskipottery/