Aluminum alloys 2011, 2014, 2017 and 2024 have higher resistance than other alloys. For most alloys, the 6061 plate will provide accurate readings. However if a 6061 plate is used with a 2024 load of parts, then the 2024 parts for example, the part will anodize at a lower current density initially, (due the the higher resistance) until the anode film builds sufficiently on the 6061 panel. (which will increase its resistance) As anodizing progresses, the increased resistance of the panel will cause it to match the resistance of the parts and then everything in the tank will continue to anodize at an equal rate. However this time delay can take a substantial amount of time and will cause the time calculated by the 720 rule to be inaccurate. Therefore its best to match the panel to the work being run. (see the chart to determine)
The plates we provide are ⅛” thickness and the size is 18″ x 4″. This presents 1 square foot of area after adjusting for the mounting hole, the rounded corners, and adding back the edge area.
After repeated anodizing and stripping, the plate will lose thickness and therefore the edge area will diminish as follows. A new plate will have an edge area of 44 linear inches x ⅛” thickness = 5.5 sq. inches. Since the total area of a new plate is 144 sq. inches, the edge area contributes less than 4% of the total area. So if a plate gets to the point where there is near zero edge area, then the current density reading on the gauge will be low by 4%.