Soda sends great clouds of dust everywhere, and is essentially sand so very abrasive, it used to be used a great deal in the restoration business, its benefit lay in the fact that it is very controllable and can remove layers more finely that a more coarse abrasive like steel shot or grit. However, for most mold remediations and such we use more dry ice these days, it evaporates and leaves no mess other than what is being blasted off. While it has become more cost effective its still pricey. The problem essentially is that the paint will not come off uniformly, and while this is not a problem when blasting metal, as you expose wood around an area you are working on, passing back and forth will continue to aggravate the wood that is exposed. I had to sand down the ribs on the boat i had that was blasted, but couldnt take too much off or the clenched tacks would have been sanded out as well. Forget sanding between the ribs too. All in all you're best just to go with a chemical stripper, no real way around it! You could take a piece of wood to a sign company that makes the really nice wood ones and get them to do a test piece, they basically lay out a rubber cutout of the main picture and blast all around it, leaving the area to be painted raised. I would not recommend this as a stripping technique at all, the thought of one of the guys at my old summer job hitting a soft cedar boat with grit at 100psi is frightening, it would kill a canoe.
