How much Water for Mayim Acharonim?

Question: Are we just supposed to wash the tips of our fingers when washing mayim acharonim?

Answer: The Beis Yosef (OC 181:8) quotes Rabbeinu Bachye (Shulchan Shel Arba 1:1) who writes that there are thirteen differences between netilas yadayim for bread and mayim acharonim. One difference is that while one needs to wash all of one’s hands before eating bread, one only needs to wash one’s fingers for mayim acharonim.

Nonetheless, he writes that we pasken like the Rashba (Torah Habayis 6:1 69a) who writes that one only needs to wash until the second joint of one’s fingers.

The Beis Yosef (OC 181:8) lists another one of Rabbeinu Bachye’s differences. While one needs a revi’is for netilas yadayim, there is no specific shiur for how much water to use for mayim acharonim.

The Kaf Hachaim (OC 181:6) writes that one should be particular to only use a few drops of water for Kabbalistic reasons. Likewise, it is commendable to remove the used water (ibid. 8).

However, the Ashkenazi poskim disagree. The Mishna Berura (181:10) and Aruch Hashulchan (OC 181:7) both criticize those who just wash the tips of their fingers, writing that one needs to wash the top two joints of one’s fingers. While the Vilna Gaon (Maaseh Rav 84) maintained that one must use a revi’is and wash with a kli, the other acharonim do not require this.

In conclusion, while some Sefardim should use the small mayim acharonim sets that are both small and hide the used water, Ashkenazim who wash, should wash with a regular cup or in a sink.