maybe the rubber is worn out
No, a suction cup works by forcing air out of the space between it and the surface it's on. No air = no suction.
When you stick a suction cup on a window you force the air out of the suction cup and you create a high pressure vaccume keeping the suction cup on the window.
J.W Greene
A partial vacuum between the compressed suction cup and the flat surface.
You can improve suction it by moisturizing it's edges, this makes it stick to something longer and stronger.
Cut a potato, rub the juice on the suction cup. This really does work. I don't know why.
No, a suction cup works by forcing air out of the space between it and the surface it's on. No air = no suction.
When you stick a suction cup on a window you force the air out of the suction cup and you create a high pressure vaccume keeping the suction cup on the window.
because you are pushing air out of the space between the window and the suction cup
I wouldn't want my last suction cup to slip, just as I reach the top of the window. The geckos have a very clever suction cup design of the soles of their feet.
mounting cup
The suction cup will lose its attachment, unless it has an additional adhesive. Suction cups attached to a surface are held there by the pressure of the outside air, which is higher than the pressure under the cup. The suction cup is trying to return to its uncompressed condition, and pulls away from the surface, reducing the pressure under it.
Because rough surfaces prevent the edges of the suction cup from creating a seal, which a suction cup needs to function.
J.W Greene
if its just a small suction cup try some meths or kerosine and or dishwashing liquid or cooking oil!
A partial vacuum between the compressed suction cup and the flat surface.
its d suctuison cups