When one performs Netilat Yadayim before eating bread, he recites the Beracha of "Al Netilat Yadayim" immediately after he pours the water on his hands, before he dries them. If a person dried his hands and remembered only then that he had yet to recite the Beracha, should he recite the Beracha at that point?
Hacham Ben Sion Abba Shaul (Israel, 1923-1998), in his work Or Le’sion (vol. 2, 11:4), rules that once the person’s hands are completely dry, he may no longer recite the Beracha of "Al Netilat Yadayim." However, if even a small part of his hands still have enough moisture on them that he could make a surface moist by touching it, then he should still recite the Beracha, even though his hands are otherwise already generally dry.
It is forbidden to speak from the moment one begins pouring water over his hands for Netilat Yadayim, until he dries them and recites the Beracha of "Al Netilat Yadayim." Pouring the water over the first hand constitutes the beginning of the Misva act, and once one begins the performance of the Misva he may not interrupt with speech until he completes the process and recites the Beracha. It is also proper to refrain from talking even after one recites the Beracha of "Al Netilat Yadayim" until he recites the Beracha of "Ha’mosi" over bread (Shulhan Aruch, Orah Haim 166:1).
If a person hears a Beracha, Kaddish or Kedusha after he began washing Netilat Yadayim, may he answer "Amen" or respond to Kaddish or Kedusha?
After one has finished washing his hands, he may interrupt answering Amen and Kaddish or Kedusha despite the fact that he has yet to dry his hands. Even though he may not interrupt with general speech before drying his hands, he may answer "Amen" or respond to "Kedusha" at this point, since he completed the primary stage of the Misva.
Summary: When washing Netilat Yadayim for bread, one should recite the Beracha after he pours water over his hands, before he dries them. If one did not recite the Beracha before drying his hands, he may not recite the Beracha at that point unless there is still some moisture on at least part of his hands. It is forbidden to speak from the time one begins pouring the water over his hand until after he dries his hands and recites the Beracha. If one hears a Beracha, Kaddish or Kedusha after washing his hands but before drying them, he may respond.
