We used it for touch-up areas for wings and the rockets we build. Alodine 600 for the wings and 1200 for the rockets not sure what the difference is but 600 turns aluminum gold while 1200 turns it almost brown. You just prep and clean with isopropyl, wipe on alodine, let it sit for 1-2 min and spray it down with de-ionized water. Pretty simple
It will be a tank that I can't get to inside of. It will have to be some sort of electro-chemical deposition to make it work. AKA, anodizing.
Well if you prep the scale off before you weld it up you still could do it. It's a liquid. You could just pour a little in there and slosh it around for a minute prour it out and rinse with water. Just a thought. I Had a quart of it for a while but got thrown cause it was out of date.