Still Potting!

A year or so ago someone messaged me to ask if I was still potting. They had noticed my absence from the world of blogging, and I was able to assure them that, whilst somewhat older and slower, I was still making pots! After all this time I am not sure how many of my original online blogging friends are up and about and will notice this post, but I thought it would be good to put a few words and pictures out into the blogosphere again in the hopes that they will be helpful to someone.

 

Mug with Autumn Landscape fired to Cone 6 

Cone 6

I stubbornly swam against the tide of cone six glaze firings until very recently when I thought I had better climb down from my usual cone nine and see if I could enjoy myself at lower altitude! This change was in part due to the easier availability of clay bodies that are in fact designed for that temperature, and also the wear and tear that high firings have on electric kilns. 

Years ago I did do some cone 6 work and mostly used the Tony Hanson 20x5 cone 6 glossy glaze recipe, G1214M. It is a wonderfully simple glaze that he developed in the 1980s and uses equal weights of Wollastonite, Frit 3134, Potash Feldspar, China Clay and Silica. 

If you are new to cone 6 and don't know of this glaze then do have a look at Tony Hanson's excellent website digitalfire.com. Tony explains about the glaze and has very good information about how glazes work and how to test, modify, and adjust them, or even make your own! I found the website so very useful in my own early days of potting, as Tony was like a fisherman that provides a hungry person with a fishing rod and the necessary advice about how to catch their own fish and feed themselves! 

 

My cone 6 adventure this time around started with browsing through some of the glazes on glazy.org which is a really splendid place to look at glazes that the potting community post there and to see what other potters do with them. It is always interesting to see the wide variety of results that glaze recipes can give when others try them out. There are so many variables involved that include things like how quickly you fire to temperature, how accurately you measure the temperature that you fire to, how rapidly the kiln cools down again, how thickly the glaze is applied, where the raw materials are sourced from, and so on... the list of possibilities is very long!

Some cone 6 test bowls where I layer glazes over each other to see what will happen, this is well worth doing as it can yield very useful information.

 

I made some cone 6 tests with about 6 or 7 glazy recipes, and found several of them worked well for me, one that was particularly impressive was Jake Tackett's Maple Leaf Red. I recently used this recipe on the outside of some beer steins that I made. The recipe has 15 percent red iron oxide in it, but if you reduce that amount to around 4 percent you have a very useful iron green colour and the 15 percent version of the glaze flows very beautifully into the iron green when put next to it.

 

Beer Stein approx 150mm high x 100 diameter

Holds at least 750ml or 1.3 UK pints 

Then I wanted to try something of my own. I looked at Tony Hanson's 20x5 and wondered what would happen if I changed the frit to 3124. I wondered how much I would have to change the proportions of the other ingredients to achieve a similar glaze chemistry. So I had a happy play with some glaze calculation software that I bought many years ago from digitalfire.com (you can download a free version of it these days... or better still pay for the cloud based new one that they do now). 

I got fairly close to the original, but I then adjusted things further and also added a sixth ingredient, talc (magnesium silicate) to have better control of the expansion of the glaze... (in other words to make it more likely to fit the clay body better without crazing). 

 

My "One over the Five" glaze base with some oxide tests applied over the raw glaze. The bowl was probably about 140mm diameter, but I sold it before measuring! 

I called this new base glaze my One over the Five, and it really works very well!

Frit 3124    28

Potash Feldspar    22

Silica    17

Wollastonite    17

China Clay    12

Talc    4

 

+ zirconium    2

+ bentonite    2

 

The two further optional additions are there because a little zirconium can help make glazes stronger and also assist some colour development, and the bentonite assists with suspending the glaze in the glaze bucket and also making the unfired dry glaze surface less powdery, which is handy if you want to do some majolica type onglaze decoration before the glaze is fired.

 

Here is "One over the Five" with 1 percent cobalt oxide and some ilmenite and manganese dioxide, the latter two ingredients added by "feel" without weighing!

 

Well, there I must leave it. Thank you for reading this far if you got here! Do try the "One over the Five" recipe if you would like and let me know how it works for you! Good luck and happy potting!