Had serious problems caulking old threaded iron pipe, tried good quality Teflon tape, tried good quality pipe lube (Rectorseal Tru-Blu), tried a combination of both but couldn't stop the dripping! Old-school plumbers used hemp and paste (now frowned upon due to bacterial growth). This stuff is the modern hygienic equivalent and sealed my troubled pipe in no time. If you think you need it, buy it, it works incredibly well!