Hi
Before the development of today's stain treatment products, the only reliable way to deal with tar on a shirt was to buy another shirt. Fortunately, times have changed in the stain removal world, and there are a number of proven methods to remove tar from clothing. A professional dry cleaner can use a number of strong chemicals to completely remove tar even from white fabrics, but there are also home remedies that work nearly as well.
Most cleaning experts agree that exposure to a heat source is the worst thing for tar-stained fabrics. Heat will set the stain permanently, so never place any tar-stained clothing in a dryer or on a clothesline until you are confident the entire stain has been removed. Immediate treatment with mineral spirits or a stain removal spray should keep the tar stain from setting into the fabric permanently.
Thanks