The Oxidation of Aluminum Foil vs. Metallized Films
Myth: Aluminum/Foil products will oxidize over time and lose
This new unfounded myth has recently been propagated by a
few manufacturers and suppliers of metallized film insulation products in
hopes of directing consumers away from the higher reflective (more
beneficial) aluminum based foil insulation products.
FACT: All aluminum surfaces oxidize when exposed
to the environment. This oxidation forms a CLEAR layer over the
surface. The thickness of this oxidation layer will increase until such a
time that the layer is too thick for the environment to be capable of supporting
further oxidation of the aluminum.
With regards to an aluminum / foil insulation product,
the oxidation process does NOT diminish the reflectivity / emissivity
of the product because of the vast amount of aluminum in the product (i.e.
the aluminum remaining under the clear layer continues to reflect radiant
heat as efficiently as before oxidation).
HOWEVER, with regards to a metallized product
(which is merely a liquid aluminum sprayed onto a film or similar
substrate), this same oxidation process GREATLY AFFECTS the
reflectivity / emissivity of the product because there is so little aluminum
remaining after the oxidation process has finally stopped. Therefore,
for metallized products to maintain their integrity, they MUST BE COATED
with a protective coating to guard against oxidation.
Our high quality
RadiantGUARD® aluminum / foil insulation products DO NOT NEED a protective
coating as our product stays well within the specification requirements.