Plastic suction cups are handy for working as inexpensive hangers for pictures, clothing and more. When you need to move the location of something, plastic suction cups conveniently relocate along with the object hanging on them. Over time, however, the staying power of plastic suction cups decreases, causing them to fall to the floor. Rather than purchase new plastic suction cups, you can make the ones you already own work again with simple supplies from home.
Clean the backside of the suction cup with glass cleaner. Thoroughly spray the side of the suction cup that is pressed against the surface and allow the glass cleaner to sit on the plastic for a minute or two. Wipe the suction cup clean with a dry towel.
Wash the surface to which the plastic suction cup will be adhered using the glass cleaner. A dirty surface or dirty suction cup interferes with the suction cup's ability to stay stuck to the surface.
Rub a few drops of cooking oil onto the part of the suction cup that adheres to the surface. Create a thin, greasy film that will keep the plastic from drying out and help the suction cup stay stuck.
Press the plastic suction cup against the desired surface, making sure to press all the air pockets out from under the suction cup. Hold the suction cup in place for 30 seconds, then release.