Generally speaking, the longer a dried blood stain has been on the surface, the more permanent it is likely to become. However, depending on how deep the stain is and whether it has gone through various laundering cycles, there are still some methods that can be used to help remove or lighten the stain as much as possible. Furthermore, when treating bloodstains always test any cleaning products on an inconspicuous area of fabric before using it on your stained item.