(empirically gathered knowledge)
KXX5
K₂O 0,269
CaO 0,500 Al₂O₃ 0.391 . SiO₂ 2,997
ZnO 0,231
Salmenhaara, 1983
Trial and error, starts form a professional standing point. To the immensive amount of published formulas, it would be only a brain tease to gather your own glaze base. But to figure out how colourants work, a test serie would be considered.
The established methods for writing formulas are the empirical charts, that are wrote down fired oxide ratios and their order, and the formula (total 100g), where material are marked as unfired presectuals.
defining the nature of material research
When it comes to the buy-able glazes and the limitations, to the labourful test tile progress is meaningful to the material based art, since according to the material basedy, the behind the artwork seen material work process will be significant when reaching a certain dimension of the artwork. The material based art form and the background work, the test series too, and the ceramic artist found glaze colour tones, are material research work of a professional. The test tiles archives are usually personal, so a big work amount is usually joyed thing that has been made.
Every single test tile gives new information, every single test serie is an attempt to reach a new dimension of a material, it's not solemnly done for artworks but to adapt the materials for a studio practice - every single material test will bring new information.
Universities have their own ways of producing test tiles, and ceramic artist should choose the form and the method awaringly.
"Test tiles and small test objects mold production ín series was one of Salmenhaara's teaching methods. - - Studio ceramicists' - - position can be made better only by expanding their knowledge on the material. To avoid misunderstandings, she hoped, that test objects and trials would not be evaluated or judged as art." (Leppänen, 1998, liite 2, s.10)