Abstract: A method for welding together the broad faces of two conductive sheets increases the reliability and consistency from weld to weld. The sheets are accessible from only one side for parallel electrical resistance welding. The electrical resistance between one sheet and the other is measured and taken as an indication of the amount of dirt or corrosion in the interface between the sheets. The measured resistance is compared with a predetermined standard. If the resistance exceeds the standard, the faces are cleaned. If the resistance is below the standard, electrical power is applied to fuse the sheets together.