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My glaze testing process:


I was fortunate enough to have taken an in-person glaze workshop with Ian Currie when he was alive. It was an incredible eye-opener for me back then. I then proceeded to make a zillion of his style glaze tile grids. I still I use the my old Ian Currie glaze tile grids in another way now to test all my glazes on both white and buff colored clay. 


I think it’s just as important to create a log or record to cross-reference it all. I use an underglaze pencil to write the firing date and the tile number directly on the clay tile grid, believe me, it comes in handy years later! I wish I had done this years ago instead of having to retest the older ones now!


I test a lot. Last year I did my own version of a “glaze workshopâ€, (with myself, in my studio) – using tons of recipes I liked and collected from my favorites like: Virginia Scotchie, John Britt, James Lovera, Lana Wilson, etc. I’m STILL trying to get a good crater glaze with big crater homes, so some of these tests pics are those. From the 90 glaze tests, I ended up with 8 new final glazes. I’m picky, what can I say. 


Here’s my process (with pics) in case the little details are helpful to anyone:


1) I make the small test amounts in labeled (w/ Sharpie pen) plastic cups 

Label with:

— Glaze reference number cup #83 V5 

— Glaze name (this refers to the glaze recipe origins)

— Cone ^ #6


2) On the Ian Currie style glaze grid tile I write:

— May 2017 ^6  Tile #7 (important when you have a lot - and over the years you will!)


3) Then in my cross-reference notebook I write:

— May 2017 ^6  Tile #7

— Grid space numbers 13-14

— Glaze cup #83 V5  (

— Glaze name (this refers to the glaze recipe origins)

(the actual glaze recipe is in another part of the notebook or in a book, in which case I ref the book and page number)


4) After the firing tests yield the results:

— I take a photo of the glaze tile

— I write all my notes for that glaze test

— I add these print-outs to a physical notebook that I keep in the studio (I have digital files too but don’t usually feel like referencing digital when my hands are in clay)

— even the glazes that I do not like are important to carefully note, because years later I may use it and test in a different direction, these are sometime the most valuable ones!

— If it’s a good test, I make it one of “my†glazes and name it how I want

— add the recipe to my card file/digital files (with reference of where the recipe originated from)

— make a big bucket of my new glaze!


5) I continue to test versions, V2, V3 etc… on smaller test tile pieces until I get the result I like or interesting combo results over other glazes and underglazes.









Pieter Mostert and Joseph F like this

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