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Monna

Member Since 28 Apr 2010
Offline Last Active Feb 01 2012 12:59 AM
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Posts I've Made

In Topic: cone 10 shino, no crawling

01 February 2012 - 12:59 AM

.bumps




Keep the shino posts coming.


In Topic: Put Up Your Pictures!

12 July 2011 - 02:53 AM

Posted Image




Sometimes the kiln gods smile upon a pot.




Posted Image



In Topic: Need Shino Help

12 July 2011 - 02:35 AM


I have that data ( they do maintain a log ) I will gather it from the log. Give me a few.


Aha... not your kiln. OK. So you have little to no control of the firings?.


Yes this is true.


Are OTHER people getting Shino results that you like in that kiln, and if so, are they stacked in the same kiln areas that yours are? Are they using the SMAE shino recipes and same clay body?





The other people are using the same tried and true recipes. I m branching out to expand the current spectrum we have.


I am guessing it is a firing issue....... but without some more data hard to say for SURE. My thoughts are that the kiln is very uneven in temperature distriibution (where your pots were stacked) and the level of reduction that was done at the lower temperatures was at too high a point for the particular shino formulation to still be gas permeable to CO (prime reducing agent). Shinos, as a BROAD generalization rule, like reduction to begin lower than most other reduction type glazes. For solid carbon trap effects..... WAY lower.





You are not alone in thinking this. Stacking, cold spots, above or below the firewall etc.. Is the CO2 meter even used? At what point does reduction begin and is that change from firing to firing. The Pale shino itself is a carbon trap style.


It is also possible that at the point they are beginning reduction, the place they are using for an indication of that time is COLDER than the location in which you pots were located. Your pots were hotter... so the impact of the reduction was less. Then by the end point in the firing, some parts of the area your pots were in were HOTTER than others, resulting in the difference in melt on the different sides of the pieces.





Yes


Also, without the slight additional fluxing action of the reduced red iron oxide, the shino will have a tad higher end point cone range.... which is not helping matters in the melt department.


The shinos that are available and used countless times in the kiln I suspect have had the flux % greatly increased. I will be bumping the flux up in both shinos.


Looking at the image of the front of the kiln.... I have some questions about the exact design of the unit too that mightr relate or might not relate to your results.

best,

...............john


The kiln is loaded for another firing this weekend. I will try to get some pictures after this.

Copper reds as of late have been an absolute disaster. They pop a horrible green. This itself points in a reduction problem. However the shinos have been spectacular, except for my new recipes. It is easy to say that kiln needs to be fired with more care. Problem is finding the person to stay there and invest the time over and over. ( which I will soon be volunteer for )

Thank you for the reply. Recently getting my hands dirty into glazes. Not my subject not in grasp yet but I hope it will be someday. I was suspecting it was a flux issue. However if someone said here is a picture what is wrong like I did. I would not have had a clue. A lot of what you have said here I have heard many times in conversations about our kiln, how it is fired. This just helps me move quicker in my experiments to develop these glazes.




Again thank you. Thank you very much.




So thank you for you eye and reply.








In Topic: Need Shino Help

11 July 2011 - 02:08 AM

I had this problem once with a stoneware clay body that just didn't take to proven Shino glazes that had been in the studio for years. The Shinos crawled, bubbled and pitted, as well as some samples that it just seemed to fall off of the walls completely. I really can't tell you why exactly, because I don't have the clay body recipe it was a store bought bag. So the first thing I'd do is throw a few clay test tiles and test the glaze against several different clays.

Shino is also quite touchy regarding clay types in the glaze itself. If you've substituted a different clay, or maybe like me you're a bit heavy handed in your measurements you'll have serious problems with crawling and maturation in Shino glazes. Especially the ones that contain 20% clay or more.

Some materials especially clays can vary from year to year, bag to bag, etc. Chemists do their best to control the products we use, but they aren't infallible. EPK for instance is a mixture of clays from many sources, and I've personally found quite a range of products found in the EPK bag. Because Shino is so heavily reliant on the chemistry of the clay used variation can cause adverse effects.




Yes:


The tiles yes or test pieces




Right now everything has been tested on a stoneware. I will expand that this next week. TY








In Topic: Need Shino Help

11 July 2011 - 02:04 AM

Mona,

Can you now please descriobe the firing schedule you use to fire these pieces.......... what cones are in the cone packs in the kiln, where they are located, the rate of climb in various segments, when you maintain oxidation, neutral fire, and reduction, how you guage the atmosphere in the kiln at any given time, what the end point cone is, and then what you do at the end of the upward firing cycle.

best,

............john





I have that data ( they do maintain a log ) I will gather it from the log. Give me a few.