It's not necessarily water that you mix into the baking soda or cornstarch for a poultice. It might take some experimentation. Acetone, alcohol, hydrogen peroxide, and other solvents can be used. It depends on the composition of the stain. Make a slurry, place it on top of the stain, cover it with plastic wrap and throughly seal with tape. The solvent will seep into the stain overnight. In the morning take the plastic wrap off and allow the slurry to dry out...don't touch until it really truly dry. If you picked the correct solvent the stain should be drawn up into the now dry slurry. You might need to repeat a few times....good luck!
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