However often you raise the red, white, and blue, your flag may be getting dirty. Flying a soiled flag hardly conveys the message appropriate to it, so you’ll need to clean it. The U.S. Flag Code says, “The life of your flag depends on your care,” so here are some suggestions for treating it honorably.
If your outdoor flag is only slightly dirty, you can simply get a wet washcloth and wipe it down. Add some liquid laundry detergent to battle through the dirt or tree sap stuck on it. If the whole thing needs a good wash, then you can put it in your washing machine without damaging it. Be sure to use only cold water, and wash on a gentle setting. It’s not recommended to use a dryer since that may cause damage or wrinkle the material, so it is best to hang dry it. (The U.S. Flag Code recommends dry-cleaning indoor or parade flags.)
For Stained Flags
For tougher spots, you’ll want to create a solution made from equal parts water and a gentle stain-removing product. Apply this to the flag using only a clean cloth, and let it sit for a while until the solution sets in. You might need something a little more heavy-duty. If so, fill a container or tub with an oxygen-based bleach mixed with water and submerge the flag overnight. Then, begin your washing process described above.
Mind the Material
American flags can be made out of several different materials, so be sure to check the tag to understand the needs of the different fabrics. If you don’t pay close attention to this, you could shrink the flag or stretch it out so that it is misshapen and unusable per the U.S. Flag Code.
Vintage, old flags require more care than a normal nylon or polyester one. It is best to take these sorts of valuable flags to professional restorers or conservators for any necessary cleaning or repairs. Flags with additional adornments like gold tassels will also require special care.