Cleaning Clear Anodized Aluminum

Q. We are seeing white residue on clear anodized aluminum that we are cleaning with Detojet in a washer. Why is this happening and what can we do to prevent it?

A. There are a few reasons this may be happening, all related to low concentration, as anodized aluminum is expected to be compatible with this detergent.

Possible Reason 1: The Detojet® Low Foaming Liquid Detergent concentration may be too low in the wash cycle and the concentration of calcium, magnesium and iron too high in the water used.  This would result in white deposits of calcium, magnesium and iron oxides/hydroxides on the aluminum. This can be fixed by increasing the concentration of Detojet such that there is sufficient chelating agent present to stop these deposits. A 1-2% concentration of Detojet cleaner is a good place for most applications.

Possible Reason 2: The parts are mounted on racks and have such geometry that they cup and hold dirty wash water.  This gets carried over in to the rinse cycle, which results in a lowering of the concentration of Detojet detergent that can make deposits as in reason 1 above.  This can be fixed by mounting the parts in racks so they drain easily and do not carry over dirty wash water in to the rinse cycle.

Either item 1 or 2 can additionally be addressed by adding an acid rinse cycle before complete rinsing by using a 0.5-1% Citrajet® Low Foaming Acid Cleaner acid rinse cycle.  Note this can only be used with washers that do not use recycled wash solution sumps, but which fill and completely empty the wash system completely with each wash and rinse cycle.

Possible Reason 3: It is unlikely, but possible, that the Detojet detergent is actually effecting the clear anodize.  This can happen when there is too low a concentration of Detojet cleaner such that there is not enough silicate corrosion inhibitor present to protect the anodized aluminum.  This is likely not the problem because this usually results in darkening of the aluminum. In any case, it can be addressed by increasing the concentration of Detojet detergent in the wash cycle.

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