How does sealing of basin drains really work?

Examining basin drains, I see:

1. Chrome ring that seats on basin drain hole.
2. 1-1/2" pipe with holes near the top that threads into the chrome ring.
3. Large cone shaped rubber gasket thing.
4. Large washer under cone gasket.
5. Large nut to press cone gasket.

WHAT I UNDERSTAND:
6. Water from basin goes down the drain but can also get outside of the pipe through the holes in the pipe.
7. Water from the basin overflow (if it has one) goes around the outside of the pipe and then through the holes in the pipe and down the drain.

WHAT I DON'T UNDERSTAND:
8. Since water from the basin or the overflow can get on the outside of the drain pipe via the holes in the drain pipe, the only thing stopping leaks is the large cone gasket. --- Won't water work it's way down the threads of the pipe between the cone gasket and leak? Otherwise it seems that the large nut must be tightened sufficiently to force the rubber cone gasket into the pipe threads. But can over tightening the nut crack glass, acrylic or cultured marble basins?

Thanks,
HRG

Usually, the cone shaped washer seals things, but sometimes people will rub some plumber's putty in the threads or on top of the nut before tightening the nut up. This prevents that from happening. You'd also used some plumber's putty under the drain ring in the sink. If the sink is plastic, make sure you use a putty designed for it, or it could stain.

jadnashua said:

Usually, the cone shaped washer seals things, but sometimes people will rub some plumber's putty in the threads or on top of the nut before tightening the nut up. This prevents that from happening. You'd also used some plumber's putty under the drain ring in the sink. If the sink is plastic, make sure you use a putty designed for it, or it could stain.

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Excellent reply. I'll rub plumber's putty in the threads for safety. Also thanks a LOT for the tip to use putty designed for plastic to prevent staining. First time I've heard or read that tip. Is cultured marble considered a plastic since it is made out of resin? How about corian in case I settle on that?

Thanks,
HRG

NO! Me thinks you are confusing plumber's putty with plumber's pipe dope. Plumber's putty is a clay-like material that used under sink baskets. Plumber's pipe dope is a semi-liquid goo that is used as a thread sealant. Some folks like silicone to seal the sink baskets, but that makes removal very difficult later. Some folks like Teflon tape to seal threads, some use both tape and dope. Largely personal preference. Janashua did not advise using putty on the threads, he said to use putty under the drain ring in the sink. (That's what I call "sink basket")

Gary Swart said:

...snip... Janashua did not advise using putty on the threads, he said to use putty under the drain ring in the sink. (That's what I call "sink basket")

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Hi Gary,

Jadnashua said:
"...snip... but sometimes people will rub some plumber's putty in the threads or on top of the nut before tightening the nut up."

Seems he did say that some folks do rub plumber's putty directly into the pipe threads to prevent basin leaks via the threads. If not, hope Jadnashua will clarify.

Thanks,
HRG

This is a case where PUTTY is called for. In theory, the fat gasket , called the Mack gasket, seals onto the threads. In practice, the Mack is often hard enough that it doesn't really work itself into the threads. Rubbing putty on the threads essentially turns the threaded body into a smooth "pipe". Teflon tape wont help, pipe dope maybe....but most of the guys on here who ever respond to this question...use PUTTY. It is the only way I ever did it, and it never leaks.

jimbo said:

This is a case where PUTTY is called for. In theory, the fat gasket , called the Mack gasket, seals onto the threads. In practice, the Mack is often hard enough that it doesn't really work itself into the threads. Rubbing putty on the threads essentially turns the threaded body into a smooth "pipe". Teflon tape wont help, pipe dope maybe....but most of the guys on here who ever respond to this question...use PUTTY. It is the only way I ever did it, and it never leaks.

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Jimbo,

Thank you very much for clearing that up.
HRG

I prefer 3 hour clear silicone-the drain assembly usualy breaks free with a few gentle taps on the bottom of the popup assembly, it lasts longer than putty, and is simpler than keeping track of what may stain and what won't. Putty requires no cure time, however.

quote;
1. Won't water work it's way down the threads of the pipe between the cone gasket and leak?
2. Otherwise it seems that the large nut must be tightened sufficiently to force the rubber cone gasket into the pipe threads.
3. But can over tightening the nut crack glass, acrylic or cultured marble basins?

The answer to all three questions is YES, which is why it takes an experienced touch to do the second, without causing the third. Plumbers usually use a pipe joint compound, not tape or putty, on the thread between the gasket and metal washer. You ALSO have to use a thread sealant on the "tailpiece" if yours is metal and screws into it.

hj said:

quote;
1. Won't water work it's way down the threads of the pipe between the cone gasket and leak?
2. Otherwise it seems that the large nut must be tightened sufficiently to force the rubber cone gasket into the pipe threads.
3. But can over tightening the nut crack glass, acrylic or cultured marble basins?

The answer to all three questions is YES, which is why it takes an experienced touch to do the second, without causing the third. Plumbers usually use a pipe joint compound, not tape or putty, on the thread between the gasket and metal washer. You ALSO have to use a thread sealant on the "tailpiece" if yours is metal and screws into it.

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>> Plumbers usually use a pipe joint compound, not tape or putty, on the thread between the gasket and metal washer.<<

Can't quite visualize what you described. Do you mean pipe joint compound on the threads at the "bottom" portion of the cone gasket where the washer and nut are? Previous comments appeared to suggest rubbing putty into the threads at the "top" portion of the cone gasket.

Thanks,
HRG

Yes, on the bottom of the Mack/cone washer which allows it to slide easier and thus conform to the threads better. On top of the cone washer does absolutely nothing because there is no "pressure" to make it do anything.

hj said:

Yes, on the bottom of the Mack/cone washer which allows it to slide easier and thus conform to the threads better. On top of the cone washer does absolutely nothing because there is no "pressure" to make it do anything.

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There you go again, using common sense and logic. Sure makes a lot of sense now that you explained it. I probably just misunderstood the other posts.

Thanks!
HRG