Spackling compound is a product used for patching holes. It resembles a slightly off-white brand of frosting or toothpaste. You use it by scooping it out on a putty knife and smearing it into holes, cracks or anywhere on drywall or sheetrock that needs a smooth flat surface. After the compound dries, it can be sanded smooth with sandpaper. If you leave a can or open container of spackling compound exposed to air long enough, it will harden and become too hard to spread. Don't throw it out, however. Revive it with water.
Remove the lid from the container of spackling paste. Stab and poke at the spackling compound with the sharp end of a screwdriver until the compound is broken into marble-sized chunks or smaller.
Pour 1/4 cup of warm water into the container. Continue mixing and stabbing at the compound until the chunks begin to smooth and become smaller.
Insert a putty knife into the spackling compound. Begin slicing at the chunks, cutting them down into smaller pieces. Continue stirring, slicing and mixing the compound until the chunks are gone. Add more water 1 tbsp. at a time if needed until the mixture is chunk-free.
Insert a stick into the container. Stir and add more water 1 tbsp. at a time until the mixture has the consistency of very thick batter. It should be pliable, but not runny. It should stick on a putty knife.