Aluminum May Hate Your Detergent


Why are we seeing dark grey streaks and haze on our aluminum sterilization containers? This question was posed by a sterile processing manager after a new washer was installed along with new detergent recommended by the washer manufacturer. The new detergent consistently passed weekly cleaning tests. Could a good cleaning agent also cause discoloration?


The department requested a copy of cleaning instructions from the container manufacturer. The instructions (IFU) recommended neutral “mild” detergent.


How do we find out if the detergents meet the device IFU? Product labels rarely provide a complete answer so the next step is review of detergent safety data sheets (SDS), especially Section 9 where chemical physical properties such as color, odor and pH are listed.


How should technicians interpret pH information in the SDS? The pH scale rates chemicals from more acidic at a pH of 1.0 to neutral at pH of 7.0 to 8.0 with higher alkalinity at a pH of 9.5 to about 14.0.


The enzymatic detergent used in manual pre-cleaning was in fact neutral at around 7.8 but the new washer detergent was rated at 12.6. This is definitely alkaline and likely to affect aluminum even after dilution in the wash cycle.


Many factors must be considered when investigating stain and residue issues. Ideally to ensure material compatibility and preservation of instrumentation, start with a careful review of both device cleaning instructions and safety data sheets listing chemical properties for each of your cleaning chemicals.