Progress Report

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.