The baking soda is to be mixed in water, BEFORE being applied to the barrel to stop the rusting. Then you rinse off both the baking soda and remaining acid from the rusting compound with clean water, then dry. I like to heat the barrel up again and then spray the barrel with a fine oil, like WD40. It helps to both darken the browning( a color I much prefer), and it also helps to deepen the browning so that you don't have to worry about wearing the browning off with the sweat of your hand easily. I do the same thing with blued barrels. Oh, the barrel is heated hot enough that the oil smokes and burns off, until it cools the barrel enough that a nice " wet " coat of oil remains. I hang the barrel up to drip dry over some old newspapers, and forget about it for 8 hours or so.
I have never had a bit of problem neutralizing and " stopping " the browning process with baking soda ans water.
A quarter cup of BS to a buck of water is all that is needed. It does not take much. Water, itself, unless coming out of a shallow well, is fairly neutral. Well water can have a high mineral content, and be almost as acidic as the browning compound you use. Use bottled water if well water like that is the only water you have piped into your house. If you have a water softener, you should not have that problem, however.
