Q: "Just what is that stuff wrapped around your faucet stem?"
As I was trying to fix an old leaky faucet, I removed the handle and the nut below it and found what looked like a washer inside the nut. But my dad said it was packing, and that I shouldn't put a washer in there. What is the difference between packing and a washer?
— Nell, Austin, TX
Richard Trethewey replies: Your dad's right on the money. Packing, sometimes called stem packing or bonnet packing, is a Teflon- or graphite-impregnated string that prevents leaks around valve stems. A washer is a rubbery disk that seals out water when compressed; in the case of faucets, the washer on a stem presses against the valve's seat.
Here's a quick way to know which one to use. If water is leaking through the spout, you probably need a new washer. But if it's coming out around the handles, you need new packing. Just take out the old stuff, wrap fresh packing about three times around the stem counterclockwise, then replace the bonnet nut.