Published: July 22, 2017
Q. Specifications indicate that “Solujet is inhibited for Aluminum. Corrosion testing is advisable.” What does this mean?
A. Solujet® Low-Foaming Phosphate-Free Liquid contains sodium metasilicate which acts as a corrosion inhibitor to stop alkaline attack on aluminum. Solujet detergent would not cause alkaline attack when used for cleaning aluminum as long as the bath/wash solution is not overused and the metasilicate depleted.
The fact Solujet detergent is silicated in this manner allows it to stand out from many other popular alkaline, low foaming CIP detergents, and makes it a good choice for many cleaning aluminum applications.
The caution when cleaning aluminum is that there may be galvanic (forming a battery) attacks on aluminum that involve interactions with other metals that may be dissolved in the cleaning solution from prior use (such as in a bath), or that may be present as metal in the tank or part being cleaned. This form of attack will happen with just about any detergent solution including Solujet cleaner. Ideally you should not clean other metals in baths used to clean aluminum and should not have other metals that have significantly different galvanic potential than aluminum present in the cleaning solution.
If there is any concern that there may be other metals involved, then some testing may be advisable. If the aluminum parts being cleaned are very high value parts, then some testing would also be advisable. Certainly Solujet detergent is designed to clean aluminum safely. Aluminum is a reactive metal, especially if it has been recently machined, cut or tooled so that there is exposed, freshly cut aluminum that has not had a chance to form a protective passive layer of aluminum oxide. This passive layer formation happens naturally with exposure to air. If the protective passive layer is not formed then you can get a varying array of potentially strange galvanic reactions that are not technically corrosion. But, this will very often result in discoloration due to deposits of whatever other metal or metal oxide is present on to the surface of the aluminum.
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