Thursday, June 16, 2011

Glaze Conundrum 2011

This year has been a tough one for me and my glazes... I don't know what is going on, but several of my trusty, dependable glazes have decided they will no longer cooperate. Take a look:

1. Pharsalia Green then...
Here's my Pharsalia Green glaze. I've had this glaze for over 12 years (15?) and I've always loved it. It's from Richard Zakin's Electric Kiln Ceramics (1994 edition, page  124). This is what it used to look like (photo 1)... Nice, right? This is what it looks like now (photo 2).

Something in one of the ingredients, you say? I checked... I made a new batch just in case I had made a mistake... nothing... I can't get back to my old Pharsalia Green no matter what I try!

2. Pharsalia Green now...
Maybe it's the firing, you say? Maybe... but I'm not doing anything different AND the "sister" glaze: Pharsalia Blue is doing just fine, thank you!

Another glaze that's breaking my heart is the old Randy's Red. I got that recipe so long ago that I can't even remember when or from whom. But it was a beautiful, reddish brown glaze that broke to blacks and golds. Now it's just a mucky old brown with nothing happening, no breaking, no gorgeous color, nothing... Here is Randy's Red before (photo 3) and after (photo 4).

Both of these glazes have Gerstley Borate in the recipe. The Pharsalia glaze has 10% and Randy's has 31%... They also both use soda feldspar... 30% for the green glaze and  20% for Randy's Red.

3.Randy's Red then...
And I've got a couple other "old" glazes that are also failing.

The one thing the failing glazes have in common is that the raw glaze on a pot feels dry, rough, thin rather than powdery and smooth.

A sad state of affairs...

 Fortunately, in the meantime I have been experimenting with glazes from the Mastering Cone 6 Glazes book and have got great results with slate blue, oatmeal, and spearmint... and now with the new Selsor yellow.... I think I'll just forget about the old glazes.

4. Randy's Red now..
Any thoughts on my conundrum will be appreciated it.

Wednesday, June 15, 2011

Kiln Opening!

I had a nice firing of a brand new (to me!) glaze yesterday. It's the luscious yellow that you see in the pictures. I am so happy with it! I got the recipe from John Britt during a glaze workshop he did for The Clay Connection (in Alexandria, Virginia) last October. During the workshop, we tested the recipe in oxidation as well as reduction firings to Cone 6, and it looks equally wonderful in both.

Selsor Base

Gerstley Borate            12.5%
Whitting                       10.4%
Nepheline Syenite        56.3%
Silica                            20.8% 

Bentonite                         2%

For the yellow, add 5% rutile. We also tested a green version of the glaze during the workshop, which was with 3.5% copper carb.

And, as you can see from the picture... once again, I dropped a kiln post and broke a rally nice yarn bowl... Oh well!

Oh! And about the baby birds:
My intention was to follow the baby birds as they grew an left the nest, but I missed about a week when my grandson had to have his appendix out. By the time I got back to the studio, the baby birds were long gone (the fledge in 14 days!). I was so disappointed!