Temperature changes and variations in pore fluid salinity may negatively affect the permeability of clay‐bearing sandstones with implications for natural fluid flow and geotechnical applications alike. Cheng and Milsch (2020) investigated these factors for a sandstone dominated by illite as the clay phase.

Flechtinger sandstone, a Lower Permian (Upper Rotliegend) sedimentary rock outcropping and commercially mined at the Sventesius Quarry near Flechtingen, Germany, was selected for the experiments. Three cylindrical cores were drilled from a larger block. Subsequently, samples were prepared with polished and plane-parallel end faces having a diameter of 30 mm and a length of 40 mm. The three samples were labelled FS1, FS3, and FS4, respectively. The three samples were vacuum-dried in an oven at 60 °C for 24 hours. They were then set under vacuum in a desiccator chamber for 10 hours and saturated with deionized water for another 24 hours.

All experiments were performed with two flow-through apparatuses with details described in Milsch et al. (2008). The saturated sample is jacketed with a Fluorinated Ethylene Propylene (FEP) heat shrink tubing and is then mounted in the vessel. Afterwards, the two sample ends are connected to the upstream and downstream pumps, respectively. The flow direction, generally, is from the bottom to the top side of the sample but can be reversed for return permeability measurements.