Just think about the cost in shop utilities to preform that process.....nat. gas to heat a hot alkaline tank the size of a small swimming pool ,for day. The gallons of water it takes to do a clean rinse....twice. Gas again to bake( dry out)in a oven the size of one stall garage. Run a air compressor to blow out all of bad spots.....also sometimes the shell needs to be plastic media blasted cleaned first before it goes into hot alkaline tank .....cuts down on contaminats going into tank .....I could go on and on