Use it for: Eczema, sunburn, hives Try this: If you're using regular oatmeal, grind it into a fine powder, Dr. Schaffran says. Put a cup of oats through a food processor until they dissolve easily into a glass of water. Pour the solution into a bathtub full of warm water and soak for 15 minutes. Using colloidal oats? Just sprinkle them into the tub and say ahhh.