Cleaning Cast Aluminum with Sodium Hydroxide?

This is my first attempt at using this particular chemical bath to clean raw castings. I have used Bases in the past but the finish would darken and require a lot of mechanical cleaning. Sodium Hydroxide is a common chemical in most crystallized drain cleaners and heavy duty oven cleaners. It cut the carbon deposits well while not changing the brightness much on quick soaks and rinses. I dont recommend it as it is not the miracle treatment I was told. I am still in a search to find a better way. Vapor blasting appears to be the best solution yet.