1) One who has paint on his hand which he can feel and it disturbs him, may not wash his hands. However, if his hand is colored but he cannot feel it, he may wash his hands. (Shulchan Aruch and Mishne Berura 161)
2) If one has the scab of a wound on one’s hand which one does not want to remove (because it will cause him pain), it does not constitute a Chatzitzah and one may wash one’s hands. (ibid)
