Rust spot

akrateffil said
do you have to keep the areas wet for a time using Rust Mort? What is ballpark cost for a gallon?

like previously said, any phosphoric acid solution will work. This stuff goes on very thin and a gallon will do an entire rusty car, almost. I have used this product as well, https://www.homedepot.com/p/Krud-Ku...d7790767468512f876a0663cd29da5d4&gclsrc=3p.ds
It is around 8 bucks for 16 oz.

No, don't have to keep wet. Brush on, let is sit overnight or so and then wipe down area with water and a rag a couple of times. Let dry, ready to paint over.