How to clean tar stain on cotton

Gently remove residues with a round-edge utensil. Then put a small amount of butter or margarine on the stain, and leave for 5 minutes. Remove the surplus.

Place the item on a clean white cloth and dab the stain with another white cloth soaked in pure white spirit.

Then proceed to a normal wash, according to care instructions.
Choose a powder detergent for white textiles. For coloured textiles, use a liquid detergent.