Metal Stains on Concrete
Drill a small hole in the top of the muriatic acid bottle. This will enable you to dispense the acid a few drops at a time. Be sure that you are wearing your safety goggles and your gloves before you get started, because this is real acid, and it can hurt you.
Dispense a few drops of the acid onto the stained area of the concrete. Start small, because you do not want that acid sitting on the concrete for more than about five seconds.
Scrub the concrete and acid with the brush. All you are doing is spreading the acid around with the brush, not removing stains with it.
Hose off the entire area. The water from the hose serves to neutralize the acid, and you can simply wash the entire area off thoroughly and let the water go down normal drainage systems. When the area dries, you will see that your stains are gone.
Metal and Rust Stains on Clothing
Attack the stain immediately. If you have an article of clothing that has hung wet on a metal hanger, then you probably have a rust-stained article of clothing. Do not waste time, but immediately apply a healthy dose of lemon juice to the stain and rub in some salt. It is okay to scrub the stain with this mix using a clean towel.
Let the garment sit in the sunlight for a few hours with the lemon juice and the salt compound still in the fabric. As the lemon juice dries, add more. You should be able to watch the stain fade right before your eyes.
Add a rust-removal product to the mix. If the stain is not fading completely away with lemon juice and salt, try a rust-removal product designed to be safe for fabrics. You can usually apply this like any other stain remover just before washing.
Launder the garment as usual once the stain is gone. If you wash it before the stain has faded, then you risk setting the stain. You might want to wash the garment two times to be sure that everything has washed out before you dry it.
Cleaning Stains Off of Metal
Create a vinegar and water mix. This will remove many stains like coffee stains or stains from other metal objects from metal surfaces. Use 1 cup of vinegar and 3 cups of water.
Saturate the area with the vinegar solution. Once the stained area is covered in the solution, you will need to let it sit for at least 15 minutes.
Scrub the stain off with the abrasive sponge. You should not rinse the vinegar solution off, but use it to keep the area wet while you scrub. The stain should lift fairly easily.
Rinse the entire area with clean water. Once the stain is gone, rinse the residue and the vinegar cleaning mixture away with clear, clean water. You can let the area air dry or wipe it down with a clean rag.