Oxidation – The “White Powdery Stuff”

Oxidation is common on all kinds of siding including aluminum and vinyl, gutters and sometimes on the trim above the garage. Soft-washing and low pressure house

Oxidized siding

washing does not remove oxidation. Regular yearly house washing will greatly reduce the build up of oxidation.

One easy way to tell if the siding has accumulated oxidation build up is to run your finger across the material and look to see if any white chalky substance is left on  your finger. Often times the oxidation will start to “run off” on to windows or brick leaving white streaks that are very difficult to remove. Another  common area of run off is below window frames.

Regular yearly house washing will reduce the build up of oxidation and keep mold from starting to accumulate.

Aluminum siding is the most difficult type of siding to clean, especially if it has not been maintained over the years.  If an aluminum sided home has not been cleaned in a long time, the mildew prevents oxidation and weathering from occurring, so after the home has been cleaned, the siding can look uneven or blotchy. The areas of the siding that had the mold and mildew growth cleaned off will look “newer” and contrast the areas that have been exposed to the environment the whole time.

Oxidation is held onto the siding by a static bond. Using high pressure to try to blast the oxidized siding will easily mark and dent siding, especially aluminum.  A common way to remove it is through agitation by using a truck brush or something similar. If the siding has not been cleaned in several years, brushing may not be sufficient due to heavy accumulation and a special 2-step acid treatment may be required.

On the gutter line, oxidation  appears in a slightly different form. It will look like “tiger stripes” or black blotchy areas. Soft washing or high pressure cleaning will not remove these streaks and so after power washing these areas will look the same.  On 90% of gutters, there is hope in removing these marks.   Some companies offer “gutter scrubbing” where they will take a brush and special degreasing chemical to scrub and remove this type of oxidation.


Oxidation was last modified: February 10th, 2015 by Michael
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