Third test's the charm

I loved the second set of test tiles, but all of my glazes crazed because the thermal expansion factors didn't match my clay.  So I took my favorite ones and reformulated them to match my porcelain, with a thermal expansion factor of 5.94.

M12 with NephSy and .5 FeO turned out to be the color of the water around Grand Cayman Island, so I named it "Calypso Blue."   I hear steel drums playing whenever I see it.  This glaze ran all over (duh!) and crazed.  I wanted to add MgO to reduce the crazing but didn't want to increase the amount of flux in such a runny glaze, so I swapped talc for whiting, which substituted MgO (TE rate of .026) for CaO (TE rate of .148).

  Calypso Blue

  Nepheline Syenite...........    32.65  
  Silica......................    15.04  
  Grolleg Kaolin..............    25.77  
  Talc........................    26.54  
  Add: FeO....................     5.77  
                              =========
                                 105.77

I had to rename my Frankenstein K glaze, because after reformulation it no longer had any potassium (or sodium, for that matter).  I'm curious to see how this one turns out.  Rebecca was appalled that it had real bone ash in it (as opposed to a mystery clay with that name?), so we named it "Donner Yellow."  I hope it retains its bright yellow color.  I switched the clay in it from Grolleg to Tile 6 in hopes that the titanium would enhance the yellow and make it less speckly and odd.  We'll see.

  Donner Yellow

  Tile #6 Kaolin..............    29.97  
  Silica......................    26.38  
  bone ash....................    40.68  
  Talc........................     2.97  
  Add: FeO....................     0.50  
 
                              =========
                                 100.50

G18 with wollastonite was beautiful, but only in the version with .5 FeO.  The version without colorant was washed out and unattractive, but with the iron it turned a lovely light green.  It's a little too olive for my taste, so I decided to substitute Tile 6 for the Grolleg to see if I could get a nice mint green.  I'll still use the Grolleg version, though, because it is beautiful.  It also ended up with an intriguing black line at the edge of the glaze, which I hope to be able to duplicate.  I really need to think up better titles for these!

  Wollive Green

  Wollastonite................    16.76  
  Whiting.....................     5.59  
  Silica......................    34.79  
  Grolleg Kaolin..............    36.20  
  Soda Ash....................     6.67  
  Add: FeO....................     0.50  
                              =========
                                 100.51

  Wollive Mint

  Wollastonite................     8.80  
  Whiting.....................     5.56  
  Silica......................    35.86  
  Soda Ash....................     3.50  
  Tile #6 Kaolin..............    46.28  
  Add: FeO....................     0.50  
                              =========
                                 100.50

G18 Frankenstein Na with .5 FeO turned out to be a beautiful, robin's-egg blue, complete with speckles from un-ballmilled iron particles.  Even though it shouldn't fit, it seemed to do just fine, so I'm going to keep the recipe as is for now.

  Frankenstein Na

  Soda Ash....................     6.65  
  Whiting.....................    18.53  
  Grolleg Kaolin..............    36.55  
  Silica......................    38.27  
  Add: FeO....................     0.50  
                              =========
                                 100.50

In Celadon Blues, Robert Tichane mentions that he hopes that someone will use Cornwall stone as part of their celadon recipe. I know that I am but the latest neophyte to follow his instruction, but I have to say that he is absolutely right. I really love the light blue that resulted from the trace amounts of iron in the Cornwall stone. It was also beautiful with .5 FeO. It crackled heavily, though, so I added a large amount of MgO from talc to substitute for most of the CaO. Because both the Cornwall and Grolleg are from England, Rebecca and I decided to name this one "Brighton Blue."

  Brighton Blue

  Cornwall Stone..............    25.19  
  Whiting.....................    13.27  
  Silica......................    14.50  
  Grolleg Kaolin..............    32.82  
  Talc........................    14.21  
  Add: FeO....................     0.50  
                              =========
                                 100.50

I was surprised at the color from G18 with G-200 and .5 FeO. It almost looks like I added cobalt instead, kind of a smoky blue. It also crackled heavily, so I used dolomite to substitute MgO for CaO to lower the thermal expansion rate.

  Smokey Blue

  G-200 Feldspar..............    28.64 
  Whiting.....................     1.38  
  Silica......................    28.08  
  Grolleg Kaolin..............    37.53  
  Dolomite....................     4.37  
  Add: FeO....................     0.50  
                              =========
                                 100.50

For a project that started out to be a complete wash-out, I'm absolutely thrilled by the results I'm getting. These six glazes (seven if you count both wollastonite ones) produce a range of beautiful pastels from greens to yellows. Kind of cool when you figure that I never used any colorant besides .5 FeO.