Dry-Clean your American flag if it is old and valuable. This is recommended for American flags that are decorative with tassels and gold rope. Some dry cleaners will clean them for free.
Wash your American flag by hand. Fill a wash basin or sink with cool water and laundry soap. In your sink, scrub the fabric by hand. Most good-quality American flags are made of acetate, nylon and cotton. Acetate is used for the red stripes, nylon for the white stripes and cotton for the blue field. Usually, these types of American flags are sewn together with preshrunk cotton thread, preventing the fabric from puckering when washed by hand. Once your flag has been washed, you can lay it flat to dry or iron on a flat surface.
Many washers now have a “hand Wash” cycle. If yours does, you can put the flag in a mesh bag for delicate fabrics and wash on this cycle.
Use a stain remover on your American flag if you notice a stain or spot on it. Always use caution and test for colorfastness prior to using stain remover on spots. For difficult to remove stains try Spot Shot Instant Carpet Stain Remover.
Wash 100 % Cotton flags on the cold water setting. Do not use a dryer after the flag has been washed. Heat will shrink the fabric. Instead, lay flat to dry or iron.
NEVER use chlorine bleach.
Prior to ironing you can use some spray on sizing (laundry aisle at the grocery store) and then iron. This will give the flag a good smooth finish. You can also use a fabric protector (laundry aisle at the grocery store) to keep it from staining and soiling so easily.