Glaze reformulation help.

[Rebekah Krieger]

I mixed up this glaze after reading that it’s super runny and can be fired cone 6-10  as a new version of strontium crystal magic.  (To be used with other glazes) 
I fired it cone 6 and it seems way under fired and didn’t do anything except leave a tan haze on my porcelain. (It’s supposed to be a crystal runny white)
I feel like an idiot  because I don’t understand the chemistry to properly increase the boron. I would love somebody to at least guide me to the information. I read articles on glazy  and it seems to be way above my intelligence level. Nothing specifically says which Frits have more.

here is the recipe:  galactic indifference 

nc4 feldspar or minspar 200 - 42.4

whiting-  17.9

epk kaolin- 12

titanium -12

lithium - 4 
dolomite - 7.3

frit 3124 - 4 

bentonite -2 

 

[Min]

I'm not seeing any lithium in the recipe, did you just miss writing that or ? Glazy has this recipe for it, which includes lithium. If it got missed in the recipe it will more than likely melt less as lithium is a powerful flux. Strontium Crystal Magic is best when used when layered with another glaze or else it's likely to be a dry underfired looking glaze at cone 6. If you want to increase the boron then I would test with small additions of Ferro 3134. Ferro 3134 does not contain alumina (3124 does). Alumina stiffens a glaze.

 

[Rebekah Krieger]

Oops- yes I just edited it now. 

[Callie Beller Diesel]

I was looking over this one last week! The name of it is memorable.

I don’t think you’ve done anything wrong, I think it’s not really a cone 6 glaze. Unless maybe it needs a soak hold added in. The description states that the originator uses it in soda firing, and if you’re throwing a bunch of extra flux at it, I can see it working, but not in an electric kiln.

Flipping through the images on that glazy listing, I think the 6-10 listing might be a typo. Or just inaccurate. 3 testers posted their results of this at cone 6. One was blistered quite badly, because they’d used silicone carbide to try and get a reduction effect. Another was on a very dark groggy clay, and it looks uneven/thin/blistered. The third fired to cone 5 1/2, and it looks much as you describe: very flat white with a faint brown haze where it’s thin. 

@Min looking at the silica/alumina ratio, would this be one of those weird glazes that if you add silica to it, it’ll go glossy/mature lower? It looks like it already has a lot of boron.

[Min]

Side by side comparison of Strontium Crystal Magic (SCM) from Steven Hill in 2006 compared to Galactic Indifference (GI). Very little boron in either, strontium completely left out of the GI. Looks like the originator of the GI glaze opted to increase the magnesium at the expense of the strontium.

I think that the high amount of titanium dioxide is acting as a matting agent. Combine this with a low silica amount and you are for sure going to expect it to be matte.  Increasing the silica might get a glossier glaze, try it and see what happens. It could just be that an increase in silica just can't be taken into the melt (especially at cone 6) with such little boron. This would be my hunch at what would happen with more silica. Layer this glaze with others and the matting effect of excessive titanium is negated somewhat by the fluxes in the covering glaze. I don't think of SCM as a stand alone glaze, more of a glaze modifier. Lots of people have used SCM (both warm and cool versions) very successfully at cone 6.

BTW SCM started out as Tom Colemans "Yellow Crystal Matte" cone 10 glaze. Hill subbed strontium for the barium in Colemans glaze and 3124 for the Gerstley Borate then dropped in a couple bentonite to make up for the reduced suspension from the lack of gerstley.

@Rebekah Krieger, have you tried spraying a light coat of GI then another glaze overtop of it? 

[Bill Kielb]

8 hours ago, Rebekah Krieger said:

I feel like an idiot  because I don’t understand the chemistry to properly increase the boron. I would love somebody to at least guide me to the information. I read articles on glazy  and it seems to be way above my intelligence level. Nothing specifically says which Frits have more.

Maybe think of it this way - The earth is basically cone ten, where we get our clay, fluxes etc… - the earth- is basically a cone 10 planet. Most glazes start out as cone 10 because they are made from things we mine from the planet. We could get things to melt lower than cone 10 if we reduce the silica and alumina enough, unfortunately the lowest silica / alumina spar we have is neph sy. So certain fluxes can help us here as well. Anyway, long story short, it is easy if we use boron. 0.15 boron (umf formuła) makes things melt at cone 6 and 0.45 boron (umf formuła)  gets things to melt at cone 04.

When you look at a Glazy recipe it will tell you the amount of boron, if it’s in there. If you look in the recipe below you will see Gerstley supplies the boron to a level of 0.17. This glaze has been tested  cone 5-6 so if I wanted more boron, I would increase the Gerstley. Obviously there is much more to glazes and much to learn. Glazy is a good resource, digital fire, Katz, sue McCloud and many many more. Lots of good books written as well, including old ones as glaze science has evolved but many of the fundamentals are still true.

Hope that helps a bit.

PS if you look up the various Frits in Glazy and compare them you will see which have the most boron, silica, alumina, etc….

 

[PeterH]

18 hours ago, Rebekah Krieger said:

...
I feel like an idiot  because I don’t understand the chemistry to properly increase the boron.
...
Nothing specifically says which Frits have more.
...

I watched from the UK (then mainly cone 7-8) as the fuel crises hit US potters, and their interests rapidly shifted from cone 10+ to 6. Converting cone 10 glazes to cone 6 ones became a matter of great interest in the US. A lot of it involved this fringe element boron ( which was only available as over-soluble minerals in the UK).

So here's highly simplified overview gained from afar. I leave it to others to say if its valid or helpful.

 Boron doesn't fit well into the UMF/Segar-Formula view of the world.  Perhaps it's just easier/best to use UMF for the other ingredients, and and consider boron more as an additive.

Seger Yields to Boron at Cone 6
https://ceramicartsqld.org.au/seger-yields-to-boron-at-cone-6/

A lot of detail and explanation is given in.

Reducing the Firing Temperature of a Glaze From Cone 10 to 6
https://digitalfire.com/article/reducing+the+firing+temperature+of+a+glaze+from+cone+10+to+6

Two brief excepts:

The reason boron is such an ideal additive is that it is more than a flux, it is a glass like silica, yet it melts low. This is a marvelous oxide! One of the beauties of boron is that it is compatible with most colorant, matte and variegation mechanisms. But there is another even more important reason: Boron has a low thermal expansion; additions of it will reduce glaze crazing. This is so important because most high temperature glazes contain far more high-expansion Na₂O, K₂O than can be tolerated at cone 6 without producing crazing. In addition the low-expansion silica and alumina they contain must be reduced to achieve melting at cone 6, thus moving the glaze toward crazing.

The next questions is: What source of boron should you use? The answer is: frits. There is a boron frit out there to meet almost any fluxing challenge. However each frit contributes other oxides besides boron. This means that to reach the goal of only increasing the boron in a glaze you need to be able to reduce other materials in the recipe that contribute the same non-boron oxides as the frit. Thus, to do what I am about to describe, you need a glaze chemistry. The kinds of material juggling I am about to describe are dealt with in the videos on digitalfire.com.
... note my emphasis on only.

[Rebekah Krieger]

3 hours ago, PeterH said:

I watched from the UK (then mainly cone 7-8) as the fuel crises hit US potters, and their interests rapidly shifted from cone 10+ to 6. Converting cone 10 glazes to cone 6 ones became a matter of great interest in the US. A lot of it involved this fringe element boron ( which was only available as over-soluble minerals in the UK).

So here's highly simplified overview gained from afar. I leave it to others to say if its valid or helpful.

 Boron doesn't fit well into the UMF/Segar-Formula view of the world.  Perhaps it's just easier/best to use UMF for the other ingredients, and and consider boron more as an additive.

Seger Yields to Boron at Cone 6
https://ceramicartsqld.org.au/seger-yields-to-boron-at-cone-6/

A lot of detail and explanation is given in.

Reducing the Firing Temperature of a Glaze From Cone 10 to 6
https://digitalfire.com/article/reducing+the+firing+temperature+of+a+glaze+from+cone+10+to+6

Two brief excepts:

The reason boron is such an ideal additive is that it is more than a flux, it is a glass like silica, yet it melts low. This is a marvelous oxide! One of the beauties of boron is that it is compatible with most colorant, matte and variegation mechanisms. But there is another even more important reason: Boron has a low thermal expansion; additions of it will reduce glaze crazing. This is so important because most high temperature glazes contain far more high-expansion Na₂O, K₂O than can be tolerated at cone 6 without producing crazing. In addition the low-expansion silica and alumina they contain must be reduced to achieve melting at cone 6, thus moving the glaze toward crazing.

The next questions is: What source of boron should you use? The answer is: frits. There is a boron frit out there to meet almost any fluxing challenge. However each frit contributes other oxides besides boron. This means that to reach the goal of only increasing the boron in a glaze you need to be able to reduce other materials in the recipe that contribute the same non-boron oxides as the frit. Thus, to do what I am about to describe, you need a glaze chemistry. The kinds of material juggling I am about to describe are dealt with in the videos on digitalfire.com.
... note my emphasis on only.

Thank you. 
 

 

[Rebekah Krieger]

To answer the question of what would happen if I put another glaze on top of it. I tested this yesterday. I put “gingers magic dust” on top of an already fired tan test of GI. I ended up with some interesting crystaling and a nice pink. Not sure why the two came out pink together. But I do like pink. I can’t seem to get any images to attaché to the post to show what’s going on. 

[Min]

2 hours ago, Rebekah Krieger said:

I put “gingers magic dust” on top of an already fired tan test of GI.

If this recipe is the Ginger's Magic Dust recipe that you used I would be very careful using it. I put it into Insight as there were a few alarm bells going off when I looked at the recipe.

55 Gerstley Borate is a huge amount, it has put the boron far higher than it should be for a well melted durable ^6 glaze. Excess boron leads to a soft non durable glaze and can actually increase crazing when far in excess of what is needed for a balanced recipe.

10 Lithium Carb is also a huge amount. Shivering could be a real possibility with this glaze. When used over another glaze shivering risk will probably be diminished, either way I would test for it.

Alumina is low, another thing that will contribute to a non durable glaze. The fact that the silica is crazy high and yet the glaze is still melting demonstrates just how over fluxed and how high the boron is in this recipe. 

Sorry to rain on your parade but it's hard not to say something when I see a recipe like this. Might be okay (no shivering) for non functional pieces but I would not use it for functional pots.