A small amount of cooking oil or even petroleum jelly around the lip of the suction cup also helps the cup adhere to a surface.
Apply the chosen substance to the perimeter of the cup on the side of the lip that sticks to another surface.
Use as little as possible, otherwise the cup may lose its suction power.
How do you get suction cups to stick in aquarium?
Make Sure Suction Cups Are Clean
However, the suction cups do not need to be 100% dry. If they are slightly moist, the moisture will help form a better seal and help them stick better. However, they should not be soaking wet, just a little moist, to get that ideal suction.
How do you make suction cups stick better?
Make sure both the inside of the suction cups and your window are clean and dry before application. To enhance suction and help keep the seal tight, a tiny dab of Vaseline or cooking oil may be rubbed on the rim of the cup, or dampen your fingertip with water and lightly moisten the inner rim of the suction cup.
Why do suction cups stop working?
Basically, the seal of the suction cup is not perfect, so air can gradually leak into the inside of the cup. When there is no air pressure differential holding the cup against the wall, there is no frictional force to hold it from sliding down the wall, and it will simply fall off.