Q: What is the Shariah ruling concerning any object that prevents water from reaching any specified organ for ablution?

A: One of the conditions that must be fulfilled for the validity of the ablution (wudu) is that none of the organs which water must reach is to be covered with anything that prevents water from reaching it, such as wax, blacktop, dough, as well as the substances that many women put on their nails in what is known as 'manicure' and 'pedicure.'
Moreover and important still, as long as ablution is not valid because of such things, the prayer is also not valid if performed with an ablution done while the organs specified in it are covered with any of such things.