If you use soda blasting to remove auto paint (it will not remove rust), it is recommended to wash thoroughly with soap and water and then wash with an acid solution (I have seen 20% vinegar and water), and then rinse with water.
Harbor Freight used to sell blasting soda, they might still be selling it?
Unwashed soda will cause paint failures, as will unwashed oil residue, unwashed silicone contamination, and un-removed rust. Of course, paint manufacturers will not warranty any paint failure due to contamination.
I have painted many soda-blasted (and carefully washed) parts. However, I find that chemical paint removal and then rust-removal media blasting is most effective and most efficient in time and money.
Also, considering the cost of non-silica blast media (my preference), I looked for a local media blaster to remove rust from frames and sheet-metal parts that will not fit in my blast cabinet. It took me three years to find a blaster, but it sure saved me time, and money, and mess.
