Razor Blade Swallowing Mystery. Hamburg: Janos Bartl, 1930s. The magician swallows a quantity of loose razor blades, then asks the audience to choose one of six differently-colored threads. He consumes a length of this thread as well, then regurgitates his meal – with the shiny metal blades now strung on the thread. With six gimmicked wooden spools bearing the Bartl logo, a threading block, and a handsome wooden case to hold the apparatus. Case length 12".