This cartridge is from a 25 year old 2 handle lav faucet. There is a rubber washer but that is only used to seal the cartridge against the valve body. The operating mechanism seems to be a brass disc being compressed against a brass seat, just like a usual compression faucet except it is not a rubber washer being compressed against a brass seat.
Do I have this right?

Yes, and often the end of the stem, which is the "sealing point" and is chrome plated wears and develops grooves in it. It was called a "washerless" faucet, even though it does have a "washer" in it.

It is surprising to me that this brass-to-brass seal worked so well that this lav faucet has been drip free for 25 years and has never been serviced as far as the homeowner knows. The faucet seems to be very well made and there was very little wear and corrosion inside.
Because I could not find a replacement cartridge (our sponsor has short and extra long hydroseal cartridges but not this 3 in long cartridge, Amazon has some copies but not the original) and the pop-up drain was corroded, I replaced the faucet with a Moen. This faucet likely would have functioned well for many many more years had the dripping cartridge been replaced.

IT is NOT "brass to brass". The end of the brass stem contacts the upper portion of the rubber seal on the end of the cartridge.

Thanks, hj. That clears up what has been puzzling me since I came across this Hydroseal cartridge.



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I have had great support from Pfister and the lifetime warranty. I call the number, and explain I am the original owner. Without even asking for proof of purchase, the rep is sending me replacement parts. Cartridges, handles, you name it.
My faucet is around 5 years old.