Which number indicates that an electrode can be used in all positions and vertical down?

When referring to the classification of electrodes in welding, the last digit of the American Welding Society (AWS) classification number denotes the positions in which the electrode can be used. Specifically, a classification number that ends with the digit '4' indicates that the electrode is designed for use in all positions, including overhead, flat, horizontal, and vertical, as well as vertical down welding.

This versatility makes such electrodes particularly valuable in applications where a variety of joint orientations will be encountered. It allows welders to employ the same type of electrode across different welding situations without switching to another type that may be less versatile.

In contrast, other numbers within the classification system indicate limitations to specific positions, such as flat or horizontal only, which would restrict the electrode's use in certain applications. Thus, the number associated with the ability to weld in all positions provides clarity for welders about the electrode's capabilities, making '4' the indicator of versatility in position use.