Leak free seal for basin drain

What is the secret to getting a leak free joint where the drain connects to the wash basin? I've managed in the past, but never on the first try so I must be doing something wrong. My technique, read off of instructions for installation of the drain, is to roll a gob of plumber's putty into a rope about 1/4" in diameter and lay it in the depression in the basin where the drain goes. Then I drop the drain in, work the rubber grommet up over the drain from below, put the washer and nut on, and tighten the nut. Then I peal away the putty that has been sqeezed out around the drain and do a leak test by closing the drain plug, filling the basin and letting it stand. After 10 minutes or so I put my hand down there and find wetness. Since it gets wet when the the plug is in place it must be leaking around the putty, right?
At that point I loosen the nut and work the drain up far enough to squeeze some more putty in, but that seldom works and I have to take it all apart and start from scratch.
Could someone clue me in?
TIA
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Jag Man wrote:

That will only allow water in the basin to go down the drain.
The secret is to seal the rubber Mack gasket to the threads of the pop-up drain and also to the basin. I use silicone sealant. Apply to top surface of the Mack gasket and also liberally to the threads. If you don't seal the threads, water will spiral down them.
Jim
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But Jim, where would the water spiraling down those threads come from? Seems to me it can only come from the basin, 'cuz that's where the water is, and if you follow the threads upward you come right to that joint between the metal of the drain meets the porcelain of the basin, i.e., where the putty is. Conversley, if that joint is sealed by the putty AND THE DRAIN PLUG IS DOWN there is no way water can get to those threads. That's the test I'm talking about. I dry everything, close the plug, and fill the sink up about 3-4". After a bit the threads beneath the nut are wet. Not much, but wet nonetheless.
Now, I agree that if the drain plug is up (or the basin is full and flowing into the overflow hole) the rubber Mack gasket (didn't know that's what it's called) can be involved.
I'm no plumber, but that's what I see when I look at the drain plumbing.
Ed
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Jag Man wrote:

perfectly, then water can not (should not) leak at the nut.
But somehow, some small amount is getting past one of those 2 places and if the threads aren't sealed to the gasket, it will drip below.
I don't know the exact answer to your situation, but if it drips below, it's not completely sealed.
Jim
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On Mon, 04 Apr 2005 18:37:37 GMT, "Jag Man"

Are you rolling the putty in your hands until it's thoroughly warm and softened? See it this helps: apply the putty to the bottom of the drain set, not the basin, then very firmly work the drain set into the basin, squishing putty out and seating the drain set so when it's tightened from below it doesn't have far to go.
Adding putty after tightening down the drain set then loosening it won't work, in my experience. You have to start over from the beginning.
--
Luke


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I believe I have resolved this problem. When I removed the drain from the basin to begin fresh, as suggested by Luke, I noticed a small pointy bump in the porclain where the drain flange sits. (Kohler quality?) I used a tile cutting bit in a Dremel to gring it off. Also, I placed the roll of putty around the drain flange rather than on the porclain. When I reassembled and tightened it, no leak!
Thanks to the people who responded to this.
Ed

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