I've been working on getting out Rewards to my Kickstarter backers this week - cards, pendants, and teabowls all took wing. More of them will go out on Monday, and still more after the next test firing.
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:
Old Yellow ^6 Test 1
Cone:
6 Color: Cream/yellow
Firing:
Salt/Soda Surface: Semiglossy
Amount
Ingredient
50.5
Nepheline Syenite
16.7
Dolomite
3.4 OM 4
12.7
Zircopax
12.5
Gerstley Borate--1999
4.2
Silica
100
Total
Add
2 % Red Iron Oxide
Old Yellow ^6 Test 2
Cone:
6 Color: Cream/yellow
Firing:
Salt/Soda Surface: Semiglossy
Amount
Ingredient
55.2
Nepheline Syenite
18.2
Dolomite
3.7 OM 4
13.8
Zircopax
9.1
Frit--Ferro 3134
100
Total
Add
2% Red Iron Oxide
Old Yellow ^6 Test 4
Cone:
6 Color: Cream/yellow
Firing:
Salt/Soda Surface: Semiglossy
Amount
Ingredient
52.8
Nepheline Syenite
17.4
Dolomite
3.6 OM 4
13.2
Zircopax
13
Frit--Ferro 3185
100
Total
Add
2% Red Iron Oxide
Old Yellow ^6 Test 3
Cone:
6 Color: Cream/yellow
Firing:
Salt/Soda Surface: Semiglossy
Amount
Ingredient
48.1
Nepheline Syenite
15.9
Dolomite
3.2
Ball Clay--Old Mine #4
12.1
Zircopax
15.9
Frit--Ferro 3134
4.8
Silica
100
Total
Add
2% Red Iron Oxide
Old Yellow ^6 Test 5
Cone:
6 Color: Cream/yellow
Firing:
Salt/Soda Surface: Semiglossy
Amount
Ingredient
50.6
Nepheline Syenite
16.7
Dolomite
3.4
Ball Clay--Old Mine #4
12.7
Zircopax
16.6
Frit--Ferro 3110
100
Total
Add
2% Red Iron Oxide
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.)
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.