I have read your bulletins on the emittance and reflectance of aluminum exposed to air, but I did not see any exact numbers for both. Most importantly, I’m wondering what the numbers look like of aluminum foil that has been in service for several years and whether coated or uncoated aluminum foil will perform best for a long time?
The oxidation of aluminum foil occurs very soon after it is exposed to air. From that point on there is little change so emissivity is only slightly affected. The foil surface can corrode in the presence of certain contaminates, but that isn’t the same as oxidation.