Water-based and oil-based stains are two different types of wood stains - oil-based stains tend to take longer to dry and are easier to apply even coating, while water-based stains come in a variety of colours and don't give off strong fumes like oil-based stains.
The technician let us know when to expect him and was on time. He diagnosed the issue and showed me what he was looking for. He needed parts, which he got the next day, and returned according to an appointment...