Why can't a fish and chips oily substance come off your shirt when you dab it with water?

When you dab an oily substance, like fish and chips grease, with water, it doesn't dissolve because oil and water don't mix due to their differing molecular structures. Oil is hydrophobic, meaning it repels water, while water is polar and cannot effectively break down the non-polar oil molecules. As a result, dabbing with water merely spreads the oil around instead of removing it. To effectively remove the grease, a detergent or soap is needed, as these substances can emulsify the oil, allowing it to be washed away.