Wow!  You mean after the cat you had some metal left?!  I have two
cats and it can be terrible.  You need to neutralize the ammonia;
sounds like you have done enough.

Cleaning should proceed until there is no trace of fox red rust --
no brown at all.  Of course you have to have some metal left in order
to go down to the metal but you should try to go as far as practical.

Try to use mechanical means rather than chemical means for cleaning.
It is hard to remove all dangerous traces of chemicals.  Air abrasion
is a good method and one can find or build small units that can
literally clean the letters on small coins.

Beware, however, of the risk to aesthetic values.  Air abrasion taken
too far can burnish the metal surface and make it look newer than new.
Use air abrasion only on stubborn heavy rust.  Another good tool to
have is a glass bristle brush-you can find small ones ideal for screw
threads.

Metal has to be sealed from danger.  Danger is moisture and salts from
the outside environment.  A thorough cleaning would include removal of
oils via degreasing and careful washing of all residues including
those from any polish.  I generally finished a piece off by washing
down with Stoddards solvent then allowing to dry.

Then the object must be thoroughly dried.  Bake in oven, but be careful
that you don't melt the object: sometimes things are put together with
softer lead or other metal.  I once baked a clock statue of a man only
to find his head and arms fallen off.

When you bake the metal, say to 500 degrees F., the pores and fibers in
the metal open up; the metal expands.  You need to apply the barrier
when the metal is in this state.  The best barrier is microcrystaline
wax.  This is available from conservation supply companies and is not
all that expensive.  The wax should smoke when brushed onto the object.
Make sure you apply a through covering.

Once the initial hot coating is done I like to coat some objects a bit
more.  You can do this by applying the wax under heat lights.  I have
found this is good for objects that are pitted.

One can, for example, stand a stovepipe on end and, starting at the
top, apply the wax and then melt it to flow on a coating top to bottom.
Wax may also be colored to restore a patina effect.

Have fun!

Conrad Bladey