What condition should the client's foot be in before using an electric file on a foot callus?

Using an electric file on a foot callus requires the skin to be soft and dry for optimal results. When the skin is dry, it allows the electric file to effectively remove the hardened layers of skin without causing excessive friction or irritation. A dry surface can also prevent the buildup of debris that could impede the filing process, ensuring that the treatment is both safe and efficient.

If the skin is wet and soft, as noted in another option, the electric file may slip over the surface rather than effectively abrade the callus, making it a less ideal condition for use. Similarly, a dry and rough surface might lead to discomfort and less effective exfoliation, while warm and moist conditions can also hinder the proper use of the file. Thus, maintaining a balance where the skin is soft and dry enhances the effectiveness and safety of the procedure.