To avoid any water exchange between two layers of the soil it is necessary to cut down all capillary bridges between those sections.
A single layer of a geo-textile will not fulfil this task, because there exists a capillary connection through this textile, whereas the multi-filament fibres of this fabric acts as capillary bridges. Only a spacer-material with no capillary function stops this.
In this respect the three layer construction as illustrated with the pictures on the left side guarantees the zero capillarity within these layers.
The water drops on the surface showing the respective repellence.
This is caused by the Solaflon micro coating of the AquaHold felt.
This micro coating also prevents the fabric from becoming wet, at otherwise it would influence the air permeability of the material negatively.
A further very important point has to be observed. If a normal felt is used instead of AquaHold, there is a permanent flow of water through the untreated fabric. This water carries very small soil particles, which are filling up the space of the middle layer within shortest time. If the filling is done, the full capillary throughput is given again.
To avoid the salty seawater in contaminating the upper layers of a soil near the sea, AquaHold as triple layer is a greatly enhanced solution to this problem.