steps

Don't dull the new one, shine up the old one!

Get some 'Purple Polish' and the matching green oxidisiation remover from a car parts store.

Easy as and you will have great looking steps again.

Cheers

Anthony

Barry - Buy a small bottle of phosphoric acid (Ranex is my favourite), get a hold of a plastic spray bottle, and make up a solution of around 10-15% Ranex, to 85-90% clean water.
Spray evenly on the new aluminium, brush it around if need be, then wash the solution off after a couple of minutes.

You can also use this solution for cleaning mag wheels, and for putting a protective phosphate coating on new, bare steel.

However, if using it on steel, don't wash it off, let the coating dry, which leaves a light grey finish - which finish can be oiled, painted straight over (after dusting off any excess), or just sprayed with WD40, for a water and corrosion resistant surface.

Cheers, Ron.

Don't try and dull it down.
The dullness is due to an even layer of surface corrosion and trying to accelerate the process can lead to it getting an uneven chalky looking oxide coating, the steel mounts underneath rusting out and generally making a mess of the step.

Either polish up the other side, only look at one side at a time or live with it for 12 months and it will rapidly approach the appearance of the other side.

They generally come in pairs, so taking off the dull one and putting it in the back of the shed isn't an option?

Salt water has quickly dulled every piece of ally I ever owned.

Vinegar , pour onto the shiny one and let sit , meanwhile pour onto the 'dull ' one and scrub with a 'stiff' brush ,then rinse off both ..... magic happens ...

.
Barry,
Simple.... don't stand where you can see both steps.
Anyway, in maybe several months you won't notice a difference.

Paint it with aluminium etch.