[Clayart] Iron

Terrance Lazaroff zalt57 at videotron.ca
Fri Jul 14 10:13:42 EDT 2017


Hi Antoinette;

I don't know for sure, but I used Albany slip a while back to act as a medium for my cobalt applications.  I found that when fired in an electric kiln, the Albany slip alone, was clear with a small tinge of a very light yellow.   Nevertheless, my cobalt mixed with it and it gave me a rich clean cobalt blue

I used this slip for a project, and then it ended up on a back shelf.    One day, about five years later, I decided to reproduce my cobalt blue surface, only to find that the colour came out as a dirty blue, black.   I reasoned at the time, that the iron in the slip had oxidized, thus changing the fired  colour of the slip.

Terry at www.1001pots.com



Sent from my iPad

> On Jul 13, 2017, at 8:20 PM, Porcelain byAntoinette <porcelainbyantoinette at gmail.com> wrote:
> 
> Hi guys. I have mixed up a iron red glaze that I did not mix for a while. I used ingredients that is 10 years old and older end the end result was a flat brown instead of the reach read brown that it was before. 
> I repeated the recipe, thinking I made a mistake, ending up with the same results. 
> Then I thought maybe I used the wrong recipe and compared it with similar recipes getting to the conclusion that I did not make a mistake. 
> So someone said the problem is the iron that changed over time. This was the first time I heard that in all the 36+ years I am in clay. Is that true and if so, can I fix it? I assume that if that is true, it has to do with the oxidation process. 
> Antoinette Badenhorst. 
> 
> Sent from my iPhone




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