Posted by john halfpenny on 12/03/2021 19:00:07:
SOD , I interested to know how water is absorbed through a sealed cap -seriously.
Same way moisture gets into hygroscopic brake fluid in a sealed system. Airborne humidity is sucked in mostly around non-perfect seals and even through not-perfectly impermeable rubber brake hoses or plastic meths bottles. Little by little over a long period it keeps accumulating . Here in the wet tropics with relative humidity 80 and 90 percent year round, brake systems corrode internally if not bled and flushed with new fluid annually.
As Hopper says, but with more detail.
Molecules are tiny compared with physical objects like joints and surfaces. Water has one of the smallest molecules found - about 3 picometers, or 10 billionths of an inch. In liquid form water molecules stick together into a larger body that can be sealed fairly easily, but water vapour is more difficult to contain.