To clean stains out of bowls, leave bowl sitting with white vinegar in it. Leave it for a few days, then rinse and wipe out.
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Ever use a rubber spatula on food items like spaghetti or tomato sauce and have the spatula get stained? Or ever use a plastic food container for leftovers which stained the container? I dreaded using my Pampered Chef white spatulas when I needed them for spaghetti.
Sunlight will remove tomato sauce type stains from plastics. Just place items in direct sunlight for a few hours around midday. It will bleach white laundry too.