Even though I closed my garden valve really tight, there is still water coming out it (leaking). I also tried to remove it so I can get a new one, but this frigging thing will not unscrew! Do plumbers use some type of glue to screw these things in place? I can see some white stuff around the thread of the water pipe that goes into the valve. The white stuff is dried and it becomes powder when I touch it. I simply cannot remove the valve, no matter how hard I try. Is there an easy way to do this?