In my modelling/sculpting class at University, the work was fired but not glazed. When I bought my first kiln I wanted my first pots to be glazed.

In all the books on glazes I had read you had to make test tiles, even if you used commercial glazes. So my first glaze tests are actually the test tiles I had brushed with several Ve-Ka earthenware glazes (and later Botz brush glazes) and fired at about 1050 0C. Although most glazes on the ceramic objects differed always very much from the test tiles (and usually not in a positive way), I do regret that I have thrown them away later (moved house, you know what happens when you have to make rash decisions with all the stuff you have to move).

So alas, I haven’t got my first glaze steps anymore, which I have regretted a little bit afterwards. For the last 15 years I no longer fired at earthenware temperature (and made my own stoneware glazes), so they would have been of little use……. but still.
Luckily I still have my first “real” glaze test (and all the ones after that), a series of manganese and copper oxide tests to make a bronze like glaze. And more importantly, I’ve written down all what I had done … I had made it myself a little complicated (mole ratio weighed in grams instead of a line blend, but that’s a whole other story), and without those notes, I would never have known what I had been doing. About the “why” I’m still not sure…