A bit of information in a longish message.
Bob Powell said he bought Bread Machines at thrift shops so the next time I was in a thrift shop, I had a look and bought one for eight dollars. So I had to buy some flour, yeast, etc and went to Kitsap County's upscale big food store, Central Market. Where you can buy stuff from dry ice to hay. I bought the flour in the regular part of the store, but bought some dry non-fat milk in the bulk food section. I thought I correctly identified it on the twist on lable, but must have made a mistake because it came up as citric acid.
Well the machine did a great job on the first loaf of bread, so I went back to get some different stuff. Right now I am trying a recipe for Carob Soy Bread. I have a slight allergy to wheat, and used to buy Carob Soy Bread. But apparently no one makes it any longer.
But this has gone on long enough. I found Citric Acid amoung the spices in the bulk food section. So if you are wanting to use citric acid for passivating stainless steel, you might check your food market. And maybe ask the manager if they don't have any in stock. I don't know how this compares to the stuff that Ernie uses, but at $2.69 / lb and no shipping it could be cheaper.
Dan