Evapo-rust shelf life and use life
EVAPO-RUST has an indefinate shelf life* and can be used over and over until it absolutely stops working. Only water is lost to evaporation. EVAPO-RUST has a tremendous work load. One gallon can remove 1/2 pound of pure dry rust. Rust is about 1/17 the weight of iron by volume, which means its workload is substantial. On average, one gallon de-rusts up to 300 pounds of light to moderately rusted steel. As the iron is removed from the iron oxide, carbon from the rust is released. Some parts may have a black film after using EVAPO-RUST. High carbon steel and tool alloy steel items, when de-rusted, will have a darker appearance. The carbon can be removed simply by wiping with a cloth when rinsing with water. The more you de-rust, the blacker the solution becomes. EVAPO-RUST is spent when it is pitch black and no longer performs.
*Shelf life is for un-opened product. Once opened, The life of the bath will vary due to biodegradability (bacteria introduced into the solution). After using Evapo-Rust, it is better to cover the solution, but still allow air to the bath. Pouring the solution back into a sealed container will allow the anaroebic bacteria to begin the degredation process. Used, open baths have continued to operate for over a 12 month period.