The ruling on performing wudu' while a trace of a small amount remains on the hand

Question:
May Allah reward you. I used cement, but a small amount remained on my hand that is barely noticeable and does not prevent water from reaching it, because it was not required of me to remove it from my hand. Is there anything required of me?

Answer:
If it prevents water from reaching the skin, it must be removed, and wudu' is not valid unless it is removed. However, if what prevents water from reaching the skin is a very small amount, or if it is something not solidified that water passes through, then this does not affect the wudu'. Yes.