When it comes to sealing a jack o lantern, there are a few different methods that you can use. One popular method is to use clear packing tape. Simply apply the packing tape around the edges of the pumpkin, making sure to smooth out any air bubbles. Another option is to use a hot glue gun. Again, simply run a line of glue around the edges of the pumpkin and allow it to dry. You can also use silicone caulk, which will create a waterproof seal. Simply apply the caulk around the edges of the pumpkin and allow it to dry completely before adding any candles or lights.