Q. My company is having problems removing adhesives from aluminum plate that is used for salt spray testing. We are using Alkleen 002L cleaner and Deox NC-620 deoxidizer. D.D.
A. Alkleen 002L is a potassium-hydroxide-based cleaner. When used on a substrate like aluminum, it will severely etch the aluminum, where solution can contact it. If the residual adhesive essentially shields the aluminum from the cleaner, there will be no way the cleaner can react with the aluminum to lift and remove it. The Deox NC-620 deoxidizer also will not have an effect on the residual adhesive, since it is formulated to remove the “smut” that remains on the surface.
So while the choice of cleaners may be good for aluminum, it would appear they are relatively ineffective at the removal of residual adhesive. More than likely, you will need to use an organic solvent to at least start to lift and remove that adhesive. You could start relatively mild with mineral spirits and gradually work into more aggressive solvents. Probably the most aggressive, but also possibly the most dangerous, would be chlorinated solvents. If this is a large or on-going operation, then it would be important to look into correct permitting of the process. Additionally, it is imperative to utilize the correct personal protective equipment as required from the material safety data sheets. I also would suggest you contact your current chemical supplier to see if it may be of further assistance or find out if it can supply any solvent-based cleaner for this purpose.