Final answer:
Before placing a ceramic piece on the kiln shelf, it's crucial to ensure it is completely dry to prevent cracking or explosions during firing.
Step-by-step explanation:
The last thing you need to do before putting your piece on the kiln shelf is c) Ensure it's completely dry. This step is crucial because any moisture remaining in the clay can cause it to crack or explode in the kiln during the firing process. The earlier steps may have involved decorating the piece with techniques, such as using slip to paint on its surface, which was then fired in a kiln at about 900 degrees Celsius as mentioned by Steven. Furthermore, Beth's discussion of the kiln's temperature emphasizes the importance of dryness before firing, and the historical context indicates the level of skill involved in the decoration of ceramics, which often occurred prior to the last drying stage.