[Jonas]

Hi there.
I have colloidal samples containing particles in the ~micron sizerange and I am trying to remove salt using dialysis bags.

Now i have some questions. When I pour my solution in the bag (before suspending it in the clean water solution) it holds the water in the bag. But I don't understand this, because if water molecules cant get through, how is water able to? Is this because water have to be at both sides of the dialysis bag, or is there something elemental that I have missed?

Regards Jonas