The thing about SLUDG is that the more you use the more effective it becomes. The 40mm or handheld grenade option is attractive, but even then it would be about the equivalent of throwing a water balloon's worth of the stuff. It could hold down something weak, but for the big baddies we'd need more. A lot more. So allow me to introduce...
The Hydro-Optimized Solution Emitter, a.k.a.
The H.O.S.E.
The HOSE is a handheld device composed of a long sturdy barrel, a trigger mechanism, and a tube leading to a two-tank system attached to the underside. One tank holds about two liters of a fluid, in this case SLUDG, and the other, smaller tank is filled with pressurized gas. (Preferably something non-flammable, like nitrogen or carbon dioxide.) When the trigger is pulled, the pressurized gas flows into the chamber containing the SLUDG. This pushes the SLUDG out of the holding tank and through the tube. A tapered nozzle at the end of the barrel focuses the stream, shooting the fluid up to 100-150 feet depending on the pressure of the gaseous propellant.
The liquid tank can be refilled with other fluids as well, the most obvious choice being an accelerant like napalm or gasoline. Other options could include water or chemical fire retardant for a mobile fire suppressant tool, surface lubricant for tactical retreats, coolant/liquid nitrogen as an alternative offensive approach, or even filling both tanks with pressurized gas and using it with a muzzle mount to launch handheld grenades longer distances.