Pat your freshly cut pumpkin dry and apply a thick coat of petroleum jelly. This technique will keep the most color on your pumpkin. It will keep the pumpkin firm and moist.
Apply a generous amount of borax powder onto your pumpkin. Gently rub it into your pumpkin. This technique will create a crust of borax and prevent mold from growing in your pumpkin.
Pat dry your pumpkin and gently rub in a layer of peppermint castile soap. This technique will keep your pumpkin moist.
Pat dry your pumpkin, make sure your pumpkin is completely dry before moving onto the next step. Create a layer of clear acrylic paint. Apply enough layers to completely cover your pumpkin. Wait for your pumpkin to dry completely before placing any lights in your pumpkin. This technique will create a nice gloss inside your pumpkin while keeping it dry.