Recipes suggest placing a tray or plate under the kimchi jar during fermentation to catch any overflow of brine, which is a natural part of the fermentation process. This prevents messes and protects your countertops.
Kimchi fermentation produces gases, primarily carbon dioxide. As the kimchi ferments, these gases build up inside the jar. This pressure can cause the brine (the liquid in the kimchi) to expand and potentially overflow. Placing a tray or plate underneath the jar acts as a safety net, catching any spilled brine and preventing it from making a sticky mess on your kitchen counter or in your refrigerator. The amount of overflow can vary depending on factors like the ingredients used, the temperature, and how tightly the jar is sealed. It's always better to be prepared!
Use a wide, shallow dish rather than a small plate. This provides a larger surface area to catch any overflow, especially if your kimchi is particularly active during fermentation. Also, check the tray daily and clean it as needed to prevent any lingering odors.