You certainly can’t solder the cloth itself, if’s that’s what you mean. You can solder individual ground wires between the pots. If I’m not using braided wire (and sometimes running the braid around as the ground isn’t very ergonomic, I just use a piece of solid wire between them, vintage-Gibson style. If there’s a risk of any signal grounding on the ground wire, then I slip heatshrink over it. I use solid tinned wire of around 16 or 18 AWG for this.