[Zeke]

Well, there's blasting and then there's blasting. On the frame and underbody, you can do a clean up and then treat with acid, neutralize and paint with a number of products that will hold for a long time. While this is not by any means a restoration, it will suffice on a street car.

What I am saying is that it is possible to just knock the loose stuff off and penetrate to bare metal without total down to the last pore cleaning. You can't get to the top of the frame anyway, so the bounce back will have to do.

I'm not sure what the aversion to sand is. Walnut shells and all the dirt and scale is not going to be a lot less harsh on moving parts than sand. The debris gets into hidden places no matter how you go about it even just a pressure wash.

Which is a thought. Have you considered a pressure wash with media or having some dry ice blasting done? Soda is a bloody mess and should not be done portable.

Well, it's all messy.