Re: Can the anodized aluminum application on an object be removed chemically ?

When an aluminum object is anodized, it is placed in an acid bath and 
subjected to DC current which causes a layer of aluminum oxide to build up 
on its surface.  Immediately after being anodized, the pores of the 
aluminum oxide are open so that various dyes or other chemicals can be 
deposited into the pores to produce different colors.  The object is then 
submerged into boiling water which hydrates the aluminum oxide coating, 
causing it to swell and close the pores.  This anodized layer protects the 
rather soft and chemically reactive aluminum from scratches and corrosion.

The aluminum oxide layer can be removed with sodium hydroxide or other 
base, leaving a bare aluminum surface.  Since oven cleaner is often mostly 
sodium hydroxide, it can chemically remove the anodized layer.  Since only 
the aluminum and aluminum oxide are removed by sodium hydroxide, any 
alloying agents in the aluminum, as well as any metals deposited as part of 
the gold color are left behind as "smut."  Most anodizing shops use a large 
tank of sodium hydroxide solution to evenly remove the anodized layer.  The 
smut is then removed by another tank of solution.

A serious hazard is presented by the sodium hydroxide, either as a solution 
or as a dry material.  If it spills on the skin, there is no sensation that 
it is there; only a slippery feeling to the skin as the skin is dissolved. 
 Additionally, sodium hydroxide can cause permanent blindness if it gets 
into the eyes.  Not the kind of material to mess around with without 
protective gear.

After removing the anodized layer, the remaining aluminum is very soft and 
scratches very easily.  It is difficult to polish, particularly if you wish 
to preserve details in the surface.  I would recommend that you have your 
tray professionally stripped of the anodized layer and then perhaps have it 
electropolished.  Many plating shops in larger cities also do anodizing and 
electropolishing.  After electropolishing, a thin clear anodized layer 
would protect your tray from scratches.  In my city, a plating shop will do 
the job for its minimum job cost of about $35.  In my mind, its money well 
spent.