For those questioning the usage of pickle juice & mustard slather...
I have no knowledge on Franklin's usage but I can attest that it's good stuff..
Paul Kirk has a mustard slather recipe called "Art Brown's Mustard Slather" that he noted came from a now defunct KC BBQ joint from the '70's called Brown's BBQ.
In addition to mustard, was pickle juice, hot sauce and worstershire sauce.
It was, and still is, my favorite slather.... The hard part was that if you cook more briskets faster than you eat pickles, you have to spend extra of pickles !!!
XL BGE (#2) & Performer Platinum
Former owner: Jambo Backyard, Klose BYC, Lonestar Vertical offset w/ Insulated Firebox, Medium Spicewine, Pitts & Spitts, XL BGE (#1) & (2) Medium BGE's, 22" WSM & (2) 18" WSM's, 18" & 22" Weber Kettles