Chemical for brightening aluminium pressure die castings

Please suggest a chemical or electrobrightening process for aluminium pressure die casted parts to be anodised later.

On wrought or extruded alloys we use to use a 93% phosphoric acid and 7% nitric acid mixture with a few PPM of copper. The solution was used at 190 deg F. As you can see this is a very nasty and dangerous mixture. I don't know how it would work on castings, you would probably run into all the common problems encountered when plating castings. If you decide to try this mixture make sure you use all safety precautions and have good ventilation.

As an alternative some of the major electropolish solution suppliers have proprietary products that are very alloy specific. I would suggest contacting some of them. Two that come to mind are EPS Inc. in Menomonee Falls, Wi. and Metal Coating Process Corp. in Charlotte, NC. I'm sure there are other readers out there who can suggest more.