Slime requires an "activating" ingredient to transform it from a gluey, goopy mixture to a malleable solid. In lieu of a laundry booster, the secret activator in this slime recipe is saline solution, which can be found at your local pharmacy.
We used this solution to make Slime Valentines for kids. Fluffy slime will last 1 to 2 days in a sealed air-tight container. To reactivate it once dried, run slime under warm water.