Searching for a red part 3
From my understanding a cone 6 glaze is one of two things; it is either a cone 10 glaze with a certain amount of boron or a cone 10 glaze with a certain amount of bristol effect (which I am still unclear on).It seems to me that boron is honestly just a lower version of silica in that it’s just another glass former but with a lower melting point. After learning this I started to notice many of the cone 6 glaze recipes I have include frit 3134 in them, a frit that supplies a fair amount of boron. This seems to imply that I can make almost any cone 10 glaze a cone 6 glaze by adding fitting the chemistry to include a bit of frit 3134.
My last blog included a Glaze I now call “Gara red”, a very good red I am quite happy with. But it has no boron. it seems like I am getting lucky with the color of a cone 10 glaze unless there is a chemical reaction I am unaware of making it work at cone 6. To test this I reformulated Gara red for cone 6 with 0.15 Boron (as suggested) by a friend and tested it in the same way I use Gara red; Cone 6 oxidation with a 1 hour hold at 1800f slow cool hoping to get a more vibrate red.
Image 1 is Gara red (normal) at cone 6 ox with a 1 hour hold at 1800f .
Image 2 is Gara red reformulated to work at cone 6 with .15 boron. 1 hour hold at 1800f on a white clay body
Image 3 is Gara red reformulated to work at cone 6 with .15 boron. 1 hour hold at 1800f on a red clay body
Image 4 is Image 1 is Gara red at cone 6 ox with a 1 hour hold at 1800f on a white test tile.
Image 1 is Gara red at cone 6 ox with a 1 hour hold at 1800f .
Image 2 is Gara red reformulated to work at cone 6 with .15 boron. 1 hour hold at 1800f on a white clay body
Image 3 is Gara red reformulated to work at cone 6 with .15 boron. 1 hour hold at 1800f on a red clay body
Image 4 is Image 1 is Gara red at cone 6 ox with a 1 hour hold at 1800f on a white test tile.
I am massively disappointment at the results, Although I haven’t Given up. I have reformulated the glaze for have near the same chenistry but with .07 Boron. From the above pictures I have two hypothesis….es….sesssss, hypothesises?…. More than one hypothesis.
1: I think I am over firing the glaze I reformulated. It might work better with no hold or a lesser hold. (I am leaning towards this one because I see the huge drip in image 3 and the pure brown coming with it)
2: The brown/ red you see is some form of phase separation and I am getting unlucky with two different colors being red and brown.
I am going to put Gara red with 0.07 boron in the tester kiln just to see if i get better red ( no hold) and put gara red with 0.07 boron in the kiln with the same 1800f one hour hold as the original recipe. Hopefully one of these come out a more vibrant red or point me in the direction of making a cone 6 version of this glaze.
At the end of the day I must say I am extremely happy with the normal version of Gara red I'm getting and will most likely reduce the time it is held at 1800° f just to see it's limits on how much I need to hold it.
