Vaseline petroleum jelly creates a gooey mess when it accidentally gets on your comforter. If the substance has remained on the surface for a while and has set into the fibers, it can be harder to remove the messy stain. To get a set-in Vaseline stain out of your comforter, you must remove the stain from the surface and get out the grease that's been absorbed. With the right household supplies and cleaning techniques, you can successfully remove the greasy stain.
Scrape any old Vaseline petroleum jelly off the surface of your comforter, using a spoon.
Sprinkle the remaining stain with cornstarch until it's completely covered. Allow the cornstarch to absorb the greasy residue for 20 minutes. Remove the cornstarch with a hand vacuum.
Pour 2 ounces of water into a spray bottle. Add 2 ounces of white vinegar. Shake the bottle to mix the solution.
Spray vinegar solution onto the remaining stain until it's saturated. Allow the vinegar to soak into the fibers for five minutes. Blot the comforter to remove the stain. Alternately spray the stain and blot it with a dry cloth three or four more times.
Fill a small bowl with 2 cups of warm water. Add 1 teaspoon of dishwashing detergent.
Wet a clean cloth in the detergent solution. Wring out the excess moisture. Sponge any last trace of set-in stain to remove the grease. Press a dry cloth into the fabric to absorb the moisture and lift the stain.
Launder your comforter in warm water with laundry detergent. Check that the stain is fully removed before placing the comforter in the dryer. Repeat these steps, if needed, to treat any remaining stain.