Sealing drain tailpipe threads

I've installed a few bathroom sink drains in my house (with overflow), and there's one thing I still can't figure out: how do you prevent water from seeping down the drain tailpipe's outer threads, underneath the rubber sealing washer that seals it to the sink bottom? I can't believe you're supposed to tighten the nut hard enough to mash the rubber washer fully into the threads. Or do I use teflon grease on the threads?

Does anyone out there have a good technique for this?

I checked under a few sinks at work, etc, and they all have the Crust of Ages on the threads at this joint. Surely I can do better.

I'm not supposed to tell you this, but a very small amount of plumbers putty mashed into the threads before you pull down the rubber washer will keep that water from running down past the inside of the rubber washer.

Terry,

Thanks! Your secret is safe with me. Great website, BTW. I bought two Toto Carlyles on the basis of your recommendation, and love them.

Deane

Darn, Terry! I thought I was the only one who knew this! I was going to write a book!

leak

In the book, you can also add that pipe joint compound on the threads and the bottom of the washer also work, and it does not seize the threads so it will not come apart some day like putty will.

Thanks hj. I usually do try to do things which will make it easier for " some guy " down the road, because sometimes I am the "some guy"! I think I will switch to dope on these drains.

Dope

I also use dope and have not had problems sealing metal pop-ups to lavatories.