Wash the shirt immediately using a heavy-duty detergent or 1 cup of non-precipitating water softener. Do not use both, as washing with a detergent and the softener may set the stain.
Treat the area with a fabric-safe rust remover, if the rust stain remains. Commercial rust stain removers contain hydrofluoric acid or oxalic acid. Follow the manufacturer's application instructions. If you don't have a commercial rust remover, sprinkle salt on the stain and squeeze lemon juice over it and leave it in the sun to dry.
Rewash the shirt after removing the rust. If you fail to remove all the rust remover from the fabric, the acid can deteriorate the fibers.
Things You Will Need
- Non-precipitating water softener
- Rust remover or lemon and salt
- Test the fabric for colorfastness before using a rust remover by following the instructions on the rust remover packaging or place a drop of the solution on the edge of a hidden seam, let set for several minutes and blot dry. If the color does not change, it should be colorfast.