Mix 1 tablespoon of pool shock treatment with just enough hot water to dissolve and saturate the crystals.
Dip a cotton swab into the solution and rub the hair dye spots. Wipe off the stains with a damp paper towel. This should instantly remove the hair color splashes. For stubborn marks, reapply the cleaning agent and leave it on overnight.
Neutralize the cleaning solution by wiping the door with a vinegar-soaked paper towel. The vinegar should also keep any soaked-in solution from oozing through the refinished surface later.
Wash the entire door thoroughly with distilled water. Allow the wood to dry overnight.
Refinish the door by smoothing the areas roughened from the cleaning process with wire wool. Wipe any bits off the door with a dry towel. Brush on the maximum coats of varnish as instructed on the label for a well-protected wood surface.