Interpret a full grid of test tiles

A grid test varies two variables simultaneously. It's exponentially more informative than a line blend, and exponentially more work.

Setup

Choose two variables to test. Examples:

• Two glazes at three thicknesses (2×3 = 6 tiles minimum)
• Three colorant additions at three percentages (3×3 = 9 tiles)
• Two clay bodies with three glazes (2×3 = 6 tiles)

Fire at least 9 tiles in a grid arrangement.

After firing

1. Photograph all tiles in natural light
2. Arrange in grid order
3. For each tile, note:
   • Color
   • Surface texture (glossy/matte/satin)
   • Opacity
   • Defects (crawling, pinholing, running)
   • How it interacts with texture (if textured tiles)

The analysis

Look for patterns:

• Does one variable dominate? (e.g., thickness matters more than colorant percentage)
• Is there a "sweet spot" in the grid?
• Are there surprising combinations you wouldn't have predicted?

This is glaze chemistry in practice

Systematic testing replaces guessing. Document everything. Your future self will thank you.