In his discussion of the laws of Mayim Aharonim (washing one’s hands after eating), the Ben Ish Hai (Rabbi Yosef Haim of Baghdad, 1833-1909) writes that one should use a small amount of water for washing Mayim Aharonim. If a person’s hands are soiled, he should wash them normally, with usual amounts of water, and have in mind that he will continue eating afterward. He should then eat a piece of bread, so that his hand washing would not be considered Mayim Aharonim. At that point he may wash the formal Mayim Aharonim with a small amount of water, and recite Birkat Hamazon.
It is preferable to use specifically cold water for Mayim Aharonim, as opposed to hot or even warm water, since cold water is more effective in removing the "Zuhama" (filth) from one’s hands.
There is a common misconception that Mayim Aharonim is required only after eating a bread meal. The Gemara in Masechet Hulin states explicitly that one must wash his hands anytime he touches salt, even if he just measures salt, such as if one works in a salt quarry or in a store that sells salt by weight. Accordingly, the Ben Ish Hai writes that one must wash his hands after eating salted foods, including vegetables that one salted. Common examples of salted foods are pickles, potato chips and pretzels. Anytime a person’s hands come in contact with salt, he must wash his hands. The Sages enacted this obligation of Mayim Aharonim due to the concern of "Melah Sedomit," a certain kind of salt which could cause a person harm if it remains on the hands. Even though we do not use this kind of salt, this Halacha still applies because there are types of strong salt in use today that must be removed from one’s hands.
Summary: One should wash Mayim Aharonim after eating salted bread or any other salted food, including pickles, potato chips and pretzels. One should use minimal amounts of water for Mayim Aharonim, and the water should preferably be cold.
