There is probably as many cleaning solutions as there are shooters when it comes to swabbing between shots. With real black powder I sometimes use only a spit patch to remove the majority of the fouling. Some other solutions I've used and/or heard of is a 50/50 mix of alcohol and blue windex, alcohol and Hoppe's #9, 20:1 mix water and Ballistol and then the commercial cleaners like T/C's T-17, Slip 2000 etc. And then there are the Blackhorn 209 shooters that use a regular nitro cellulose solvent to swab between shots.
As stated above I normally use either a spit patch or an alcohol/blue Windex solution. But lately I've been trying alcohol and Hoppe's. Always one wet followed by one dry - both sides.