Someone who washes his hands with less than a Reviit of water needs to dry the handles of the washing cup. However nowadays the cup holds much more than a Reviit you don’t have to do it.
Explanation:
The Mishna in Yadayim 3:4 writes that one needs to wash his hands twice ion each hand to make them pure. Tosfot (Chullin 107) says you should wash three times; one takes off the dirt so there should be no Chatzitzah. Two to purify the hands. Three is to purify the Tameh water which is on the hands now. So ruled the Semag and the Tur. However the Misha in 2:1 if you pour a Reviit of water on one hand then he does not need to wash three times on each on hand , rather just once is enough. So Rules the Shulchan Aruch (162:2) : When one washes his hands he pours a little from the Reviit to take off the dirt and Chatzitzot, and then he pours water a second time and then that water becomes impure. Then he should pour a third time to purify the water on his hands. If his hands have no dirt then he only needs to spill a Reviit on both hands .The Mishna Berura explains the reason why a Reviit does need a second Netillah, a Reviit at poured at one time is like a Mikvah which purifies, so too these waters are pure and it does not need second waters.
We see that even if there is impure water on your hands, pour more water to wash them off and the e hands are pure.
The Mishna in Yadayim however (2:3) writes : If one washed one hand and rubbed it one the other it becomes Tameh.
The Tur explains if you pour water on one hand and rub it on the other this Netillah is not valid. The Rosh says even if afterwards he pours on both hands. It would seem to be a contradiction though. When you have tameh water on your hands after washing then you may wash it off. When you rub one hand on the other you can’t wash off that Tameh water?
We must answer when the water becomes Tameh from itself then you may pour on water a second time nad it will purify it. If a hand becomes Tameh from the other hand or from someone else who did not wash his hands, it is invalid and he must dry his hands and start again. So rules the Shulchan Aruch (OH 162:4). Ones should therefore be very careful not to rub his two hands together if the water ono his hands are still Tameh, so too own should be careful not to touch one hand to the other when they’re wet.
The Shu”t Halachot Ketanot (Kaf Hachayim 31) says that one should not touch even a little baby’s hand if his hands are wet from Netlliah. If a Goy touches his and it is unclear how to rule.
There is a difference between touching his two hands directly and touching with something else. The Shulchan Aruch writes pour on each hand a Reviit and then rub them together. If he pours a Reviit on each hand he may rub them together without any problem of Tumah. If he washed one hand and touched the other he must dry his hand sand start again. The Mishna Berura says that if he made a bracha already and someone touched his hands he should wash again without a bracha.
The Mishna Berura (162:45) quotes the Acharonim that if he took the washing cup with his wet hand the hands becomes Tameh from the water on his hand since the first pouring is Tameh and then he takes it with his left hand the left handle becomes Tameh therefore one should dry the handles.
That is the reason o saw some people drying the handles of the cup. However that is only if the first pouring was less hand a Reviit and the water is Tameh but if you poured more than a Reviit at once then you don’t have to worry about it. The Mishna Berura himself says it : the best idea is to use a full Reviit on each hand or to pour twice on each hand.
