The most common type of salt bridge is a U-shaped glass tube, which is filled with an electrolyte solution. The electrolyte may be contained by agar or gelatin to prevent intermixing of the solutions. Another way to make a salt bridge is to soak a piece of filter paper with an electrolyte and place ends of the filter paper in each side of the half-cell. Other sources of mobile ions work too, such as two fingers of a human hand with one finger in each half-cell solution.


