The suction cup is a versatile and effective tool used to securely hold or suspend a wide variety of objects, including window shades, bird feeders, shower caddies, shelving and other organizational items. Suction cups work best when attached to smooth, non-porous surfaces such as glass, tile, fiberglass and metal; however, there may be times when they lose their suction, or just won't stick. Fortunately, you can improve a suction cup's seal by properly preparing the surface, and creating an air-tight seal.
Choose a flat, smooth surface such as glass, tile or stainless steel. Avoid rough-textured, porous surfaces, since these surfaces allow air to slowly seep in, which can loosen the suction and break the hold.
Spray glass surfaces with a light layer of glass cleaner. Allow it to set for a few minutes, then wipe it clean with a soft, lint-free cloth. Suction cups will not stick to a dirty surface for long.
Spray shower and tile surfaces with all-purpose or bathroom cleaner. Allow the cleaner to set for a few minutes, then wipe the area clean with a damp sponge or washcloth. Use a dry cloth to completely dry the surface and remove excess moisture.
Remove soap scum and oils from shower walls by applying rubbing alcohol to the area. Allow the rubbing alcohol to air dry, do not wipe it off.
Wash stainless steel surfaces with warm soapy water. Dry with a soft, lint-free cloth. You can alternatively use rubbing alcohol, or window cleaner to remove any grease, oil and fingerprints.
Wash the inside of the suction cup with warm, soapy water. Shake off any excess water.
Strengthen the hold by dipping a cotton swab into a jar of petroleum jelly. Apply a thin layer of the jelly to the inner edge of the suction cup's rim, then wipe off excess jelly. You can alternatively spray the rim of the suction cup with aerosol hairspray. The chemicals in the petroleum jelly and hairspray act as a seal preventing any air from getting into the suction cup and loosening it.
Position the suction cup where you want it. Firmly press the center of the suction cup, and hold it down for a few seconds, or until it makes a small burping noise. Check for air bubbles between the cup and the surface, then slowly release the pressure.
Gently tug the cup to make sure you have created an air-tight seal. If the cup moves, even slightly, remove it and repeat the process again — pressing firmer next time. Allow the suction cup to set for 24 hours before adding any weight.