The ingredients you need to make wallpaper paste include flour, corn or potato starch, alum powder and about 3 cups of water. Other formulas recommend sugar and clove or tea tree oil. Necessary equipment includes a large saucepan and a resealable jar.
Making wallpaper paste begins with choosing a starch. For instance, the recipe from The Old School recommends 1 cup wheat, corn or rice flour, while the recipe from The Poor Sophisticate calls for 2 tablespoons of cornstarch dissolved in 1/4 cup cold water.
Next, bring 3-4 cups of water to a boil and slowly add the starch, stirring constantly to prevent scorching until the mixture has a stiff consistency. If the paste hardens in the pan, add small amounts of warm water until the paste is loose enough to stir again.
Once the paste thickens, remove the pan from the heat and keep stirring until the bottom of the pan cools to prevent sticking. Then let the paste cool. Spoon or pour the cooled paste into your resealable jar. Refrigerated, it should keep for two weeks.
Clean up any spilled paste with warm water and a sponge. For dried-on paste, saturate a sponge, and set it on the spilled paste. Wipe and reapply the wet sponge as necessary.