With explosives in general, the way that reaction rates are slowed don is by adding inert fillers, The Germans did this when they began to run short of Amatol, adding salt to make up the volume.
I would recommend that this experiment is done under near-vacuum or better - generally if you create a sudden high-current discharge inside a tube with much gas in the sudden shock-wave and thermal expansion it creates inside will cause it to shatter in a fairly energetic way. What ElonM called 'rapid unscheduled disassembly'.