Cleaning Aged Aluminum

Q. How to clean weathered oxidized or aged aluminum with a dark grey buildup of oxides especial architectural aluminum or decorations on buildings.

A. We do not have a product suitable for this but we do have recommendations. Citranox and Citrajet are well suited to cleaning freshly manufactured aluminum items, but not aged and weathered aluminum items. To remove this kind of oxide buildup requires the use of hazardous hydrofluoric acid cleaners or ammonium bifluoride cleaners. We do not handle anything that hazardous. There are companies that make these kinds of cleaners.

For industrial scale cleaning look for Magic Aluminum Cleaner from ABC Compounding 800-795-2222. For small scale use, it is possible to go to an automotive supply place and buy Mag Wheel Rim cleaner products that if you look at the labels you will find the ingredients hydrofluoric acid cleaners or ammonium bifluoride. Note these are highly hazardous and should be handled with skin and eye protection. They can corrode glass.

The resulting surface from the use of these cleaners will not be bright, but the dark stain of the oxide will be removed and a dull aluminum surface will remain. To make it bright from there, you typically need to use an aluminum polish. Typically you would use an aluminum sealer after polishing. Note that in architectural aluminum if they have weathered underneath the sealer over time, a sealer often has to be removed by a high alkaline cleaner such as Solujet or Alcojet prior to using the hydrofluoric acid cleaners or ammonium bifluoride cleaners to then clean it – and of course it has to be sealed again after use.

I understand that on door frames and other small architectural aluminum, they use lacquer to seal the aluminum. We do not have products or expertise for this kind of aluminum cleaning and we would thank people for coming to us with their cleaning needs and suggest they contact ABC Compounding or use a Mag Wheel cleaner, hopefully next time we will be able to help them with an Alconox product.

Specifically we have had people try to use Citranox or Citrajet and fail on large aluminum sculptures at museums, on aluminum tram frames for the tram at Roosevelt Island in Manhattan, for shiny aluminum components of trucks and horse trailers, on the aluminum decoration on a car dealership, on aluminum window frames, and on aluminum sky scraper architectural details. Unfortunately since Citranox and Citrajet are good for cleaning fresh aluminum to remove particulates and oils to prepare the surface for later coating or bonding, we tend to get people who think it will be good for aged, weathered or oxidized aluminum.

Need more information about one of our critical cleaner for cleaning aluminum?  Click to download each detergent’s technical bulletins and/or Material Data Safety Sheet (MSDS).