This recipe makes enough sticker gum for hundreds of stickers.
4 tablespoons water
1 envelope unflavored gelatine
1/2 teaspoon corn syrup (optional)
1/2 teaspoon lemon or vanilla extract (optional)
Put 1 tablespoon of cold water into a small bowl or cup. Sprinkle the unflavored gelatine over it. Let the gelatine soften for 5 minutes.
Pour 3 tablespoons of boiling water into the softened gelatine and stir until dissolved. If you have trouble getting the gelatine to dissolve, bring it to a boil in the microwave for just a few seconds.
For a final touch, give your sticker gum some flavor by adding 1/2 teaspoon corn syrup and 1/2 teaspoon lemon or vanilla extract. Store the sticker gum in a baby food jar. Keep it refrigerated when you are not using it. It will keep for months, but it will gel overnight. To return it to a liquid state, place the jar in a pan of hot water.
To use the sticker gum, brush it thinly on the back of the sticker. The sticker will curl as it dries. When it's dry, moisten the sticker and apply it to paper.