Well heres the test subject. I put a cut up plastic ziplock bag over it and rubbed the bubbles out with my finger leaving a fair amount of it under the plastic. This $9.99 tiny bottle of evaporust gel, looks like yellow snot, and has about the same consistency. I used an acid brush to brush it on evenly and cover with the plastic to prevent it from drying out. It didnt take much of it to cover the area i brushed. So this stuff may go the distance materialswise on fair sized jobs. I did this about 7:15pm. It says to clean it off in 2 hours. I plan on checking on it around 9:15 and see how it looks. I may try a wire brush on it to see how much rust comes off. And if i need to reapply it, and let it sit overnight. I have a TSP and water solution ready for a rinse. I may do another spot like this on the door with naval jelly and see how that goes. Maybe compare the results.