Its just hot water that helps oxidize-anodized Al to a sapphire layer.
Steam to hot baths with or w/o dye added. Just air takes way longer.
All Al will under go this reaction unless coated from water/oxygen donors.
Electrolysis and electrolytes often added to speed up or thicken
the layer formation or dye setting. Food colors work fine btw.
Rough or polished same layer. but rough has more pores to collect
grime and colors unevenly is all.
I polished primary wiped it with talc powder to remove the
waxes of buffer compound, then take a propane or hotter
torch and paint the flame over the surface.
Combustion and humidity provides water, air the oxygen
and the heat gives increased speed of reaction and slight
melting of microscopic rough edges for a bit more mirror.
Al is the most reflective metal when polished.
Also a good polish will reflect the infra red of internal
combustion if wanting to do a head up all shiny.
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hobot
