A plastic doll can acquire all sorts of stains during its lifetime. Typically, ink stains occur from a child drawing on the doll, accidental pen or marker nib contact, leaked ink, or wet, ink-stained fingers leaving behind fingerprints. If the stain is from a water-soluble ink, a slightly soapy cloth will do the trick to remove the ink from the plastic. Permanent ink stains on the other hand require more effort in the form of ink breakdown from a solvent or abrasive cleaning tool.
Press a paper towel or microfiber cloth against the ink if still wet to absorb as much of the stain as possible.
Soak a cotton ball or corner of a cloth with rubbing alcohol or nail polish remover and press the ball against the stain for approximately 40 to 60 seconds.
Blot the stain until the ink transfers from the plastic surface of the doll. Add additional alcohol or nail polish remover to clean cotton balls or cloth and continue blotting until you've removed the entire stain.
Wipe the stained area with a slightly soapy cloth when finished.
Rinse with a damp cloth and wipe dry.
If you're dealing with a tough stain, rub the surface gently with a damp melamine resin foam eraser or a pink or white artist's eraser to wear the stain from the plastic. If you still can't remove the stain, try a commercial ink stain removal product on the surface.
Test your solvents and abrasive cleaning tools on a hidden area of the doll before cleaning to make certain that the plastic won't become damaged during cleaning.