It has a ultra-quiet pad, hydroloc core, and a scratch resistant urethane with aluminum oxide wear-layer (see below). 

Contaminants in the air in our homes and buildings from household cleaners to hairsprays and everything in between have a tendency to react with and oxidize the copper used in air conditioning coils.

You found the problem and “patch” won’t stop the cast iron from oxidizing around it.

I am not suggesting doing this for the roof but two ways to convert insoluble iron oxide( rust ) to a soluble form that is removed with a water rinse is to use either oxalic acid ( 5% solution on the rust for about 30 minutes( can wet towels so it adheres and does not run off) in water or a commercial product called "Iron Out" which is sodium hydrosulfide I think.

Usually aluminum siding with paint that is oxidizing leaves the residue...if it was alum. we'd wash it really well then prime and paint.

The one that looks interesting is the air type that oxidizes the water coming in and then filters it out then back washes the filter.  

Apply solution of oxidizing bleach (chlorine or perborate) Do not use chlorine bleach on wool or silk. 5.

It "oxidizes" the pollutants leaving you with fresh O2 to breathe and no smells!

Supposedly this gets rid of about 80% of the smell.I also ordered another product called "Stink Free Instantly,"which works as an oxidizer rather than an enzyme and will supposedly treat any left over smell that is left from the enzyme treatment. 

If oxidation still exists after washing use an additive to latex paint.