 A major problem was how to test the explosives that he produced.Eventually Klepfisz bribed his landlord to let him test the home-made bombs in a deserted limekiln in a factory building owned by the man.Though the extent of Klepfisz's operation is unknown, in 1964, Polish workmen carrying out work on the site of the former factory unearthed 100,000 explosive-filled glass detonators for Molotov cocktails.