Speaking of which! The first batch of glaze conversions - five ^6 versions of Old Yellow, my favorite out of the Watershed Glaze book. The ^10 original looks like this:
Neph Sy 7155
Dolomite 2363
OM-4 482
Add:
Zircopax 1792
RIO 240
That's kind of a weird recipe, right? With like 18% opacifier added after the total. This sounds like a job for Glazemaster! The first thing I had to do was rebalance the recipe so the only ingredient below the total line was red iron oxide. After I do that, the recipe looks like this:
Old Yellow
Cone: 10
Amount Ingredient
60.7 Nepheline Syenite
20 Dolomite
4.1 OM #4
15.2 Zircopax
100 Total
Add:
2 Red Iron Oxide
Next I look at the proportions of alumina and silica by the Unity ratios, which the software kindly tells me, otherwise I'd be up all night counting atoms. Alumina is at 0.429; silica is at 2.106. Remember these are relative to the proportion of flux, which is always set to 1.Then I'm gonna compare those numbers to the ranges I found in Cushing's handbook. (There's a way to compare to limit formulas within the software also, but I've got the Cushing numbers right here in front of me.)
According to the good professor, in a satin matte cone 10 glaze, alumina should fall wiht in the range of 0.25-0.6. So we're good there. Silica should be within the range of 2.0-5.0. Also good.
To change this to a ^6 glaze I have to add a a flux.( I can't just increase the flux - dolomite - that is already present, because it's not a strong enough flux at ^6 to persuade the silica to melt.) But adding flux is going to mess up those ratios that I've been talking about, so depending on what I add - a commercial frit, or a material like gerstley borate or lithium - I may have to add more silica or clay (the usual source of alumina in a glaze.) Here are the test recipes I came up with:
I mixed all of these up in the glaze kitchen, storing them in those little plastic tubs you buy at the supermarket to keep leftovers in. (Plan A - to eat enough Talenti Gelato to use those containers - was a non-starter, even in hot weather like we've been having.)Old Yellow ^6 Test 1
Cone: 6 Color: Cream/yellowFiring: Salt/Soda Surface: Semiglossy
Amount Ingredient50.5 Nepheline Syenite16.7 Dolomite3.4 OM 412.7 Zircopax12.5 Gerstley Borate--19994.2 Silica
100 Total
Add2 % Red Iron OxideOld Yellow ^6 Test 2
Cone: 6 Color: Cream/yellowFiring: Salt/Soda Surface: Semiglossy
Amount Ingredient55.2 Nepheline Syenite18.2 Dolomite3.7 OM 413.8 Zircopax9.1 Frit--Ferro 3134
100 Total
Add2% Red Iron Oxide
Old Yellow ^6 Test 4
Cone: 6 Color: Cream/yellowFiring: Salt/Soda Surface: Semiglossy
Amount Ingredient52.8 Nepheline Syenite17.4 Dolomite3.6 OM 413.2 Zircopax13 Frit--Ferro 3185
100 Total
Add2% Red Iron Oxide
Old Yellow ^6 Test 3
Cone: 6 Color: Cream/yellowFiring: Salt/Soda Surface: Semiglossy
Amount Ingredient48.1 Nepheline Syenite15.9 Dolomite3.2 Ball Clay--Old Mine #412.1 Zircopax15.9 Frit--Ferro 31344.8 Silica
100 Total
Add2% Red Iron Oxide
Old Yellow ^6 Test 5
Cone: 6 Color: Cream/yellowFiring: Salt/Soda Surface: SemiglossyAmount Ingredient50.6 Nepheline Syenite16.7 Dolomite3.4 Ball Clay--Old Mine #412.7 Zircopax16.6 Frit--Ferro 3110
100 TotalAdd2% Red Iron Oxide
I have a ^10 firing coming up, as I am trying to keep up with all my outlets at the same time I execute this project. (That wasn't the original plan, but baby, things change. Moron that later.) That should happen next week, with the next ^6 test hard on its heels.
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