Richard this is definitely a question for you and comes from Steven in Cupertino California and he writes when making a threaded plumbing connection when should you use teflon tape pipe dope something else or nothing at all well it's a good question when most people think of threads they think of this it's a machine thread it's a straight thread most nuts and bolts have it and you can make that nut go up and down because this is straight this is not the type of thread we use normally in plumbing we use one called a tapered thread so if you look at this piece of pipe there was material right here and someone took a pipe dye and cut threads and you'll notice if you look carefully that the thread is smaller right here and it gets bigger as it goes up I never noticed that before so now as you take a tighten that in the taper gets tighter huh all right so on a stray thread as this nut moves it never gets tighter until it hits something it's right but as that thread travels it tightens up that's right so even when you tighten up though it still would not be liquid tight you still need some form of thread sealing all right so what's sealant to do you use well nowadays people use in plastic for everything so the the popular thread sealant is this is called teflon tape it comes on rolls yeah the best way to apply this is to hold the work in your left hand and now you'll notice I'm going to go around the Teflon does not have any adhesion so you have to pull it tight enough so it seals onto itself it's almost filling those threads its retaining its ruin so you got two or three times and now when you get to this point the important thing is to pull it tight enough so it seals on to itself okay and then you just tighten it in great all right now this is what's used nowadays but I still am partial to this some sort of pipe sealant it would pipe dope they call it this is this two different brands that we use when we go on here with the threads so this is kind of a liquid I mean is this a is this a permanent seal that's going to set up well the nice thing it'll fill between the threads but it'll never set up so hard you can't take it apart you always want to be able to be able to take the work apart later right all right good so that would just thread right in right here okay yeah and tighten it up now when I'm connecting to old work like this radiator connection I'm going to use wicking so I'll still use pipe dope and when you say wicking are you talking about this sort of ball thread here that's right once you pull out a single piece of that working just one strand yep okay that's for you just snap that off for you so now in this case I'm actually going to put this wicking so it lays right into the threads so what do you know you're filling up those absolute or absolutely so now what happens is as liquid touches it that string or wicking will just expand slightly so will act like a cocking oh very clever so in plumbing it sounds like anytime you have threads you're sealing them well you have to seal them but I actually won't use thread sealant on every thread let me show you what I mean this is a radiative valve on a you know radio is right here the pipe comes up here and let's talk about this connection it's actually a union connection now in this case this thread is straight the knot is straight so it's just going to pull two things together the liquid tight connection is going to be because we bring this face tight enough against this one's called a ground joint yeah so I'm not going to use any thread sealant on right there on these threads but I might use a little touch of pipe dope right here because well as I make these pieces together it's going to just make a nice tight seal help us make a nice tight seal okay now there are actually some connections where there's a rubber gasket already installed right on some of these new faucets these connections right here again this is a straight connection this is a water supply going up to the bottom of a lavatory and in this case I don't need any pipe dope right here there's a rubber gasket and we just want to make this tight enough to compress that rubber gasket to the bottom of the faucet great information so Steven I think that is the straight dope on making plumbing seals you