Why is ketchup so hard to get out of clothes?

Ketchup is difficult to remove from clothes primarily due to its high acidity and the presence of pigments and oils. The acidity can cause the stain to set quickly, while the tomato solids and sugars can adhere to fabric fibers. Additionally, when ketchup dries, it can become sticky, making it harder to lift from the material. Prompt treatment with cold water and appropriate stain removers can improve the chances of successful removal.