TL;DR
A plastic mixing bowl that feels clean can still hold enough fat to stop egg whites from whipping. Plastic surfaces retain a fat film that lukewarm water does not remove, which is why bakers reach for metal or glass when whipping whites. Wash bowls in very hot water with plenty of detergent, and wash the outside and base rim too.
Why plastic holds grease
Plastic has a surface that oil clings to more readily than steel or glass, and older plastic that has been scratched by whisks and spatulas holds more still.
That matters for more than the feel. Fat interferes with the protein network that gives whipped egg whites their volume, so a trace of oil in a bowl can keep meringue from forming at all. It is a well-known baking failure and it is usually a bowl problem, not a technique problem.
If you whip egg whites, use a stainless, glass, or copper bowl rather than plastic, and wash it in very hot soapy water beforehand. Some bakers wipe the bowl with a little vinegar or lemon juice on a paper towel and then dry it, which removes trace fat -- that is fine on stainless and glass. Do not do it on aluminum, which pits in acid.
Plastic's oil-holding behavior turns up across the kitchen, including on how to clean a colander and strainer and on silicone tools, and it is one of the material rules in our guide to cleaning kitchen tools without damaging them.
How do you clean a greasy mixing bowl?
Wash it in water as hot as you can safely handle with plenty of dish soap, scrubbing with a brush rather than a sponge, and let a badly greasy bowl soak for ten to fifteen minutes first. Rinse hot, and dry it rather than leaving it to drip in a stack.
The parts of a bowl nobody washes
The outside. Bowls nest, so residue on the outside of one transfers to the inside of another. Wash the exterior every time.
The base rim. Every bowl has a foot or a rolled edge at the bottom, and that ring sits in whatever is on the counter. On a stainless bowl it is a rolled fold that holds water and drips it out later.
The non-slip silicone ring. Many bowls have a silicone base ring that pops off. Underneath it is a recess that collects water and food. Pull the ring off, wash both parts, dry them, and refit only when dry -- that gap is a classic spot for dark spots to develop.
The rim lip. A pouring lip or a rolled top edge has an underside that a quick wipe misses.
Material rules
Stainless steel. The easiest and the best choice for whipping. Hot soapy water and a brush. Avoid chlorine bleach, which pits stainless steel, and steel wool, which leaves iron particles that rust in place. Rainbow heat tint and water spotting are cosmetic; a baking soda paste handles both.
Glass. Dishwasher safe and non-absorbent, so it does not hold odor or grease the way plastic does. Its two risks are thermal shock and chipping. Do not move a glass bowl straight from a hot oven into cold water, or from the refrigerator into hot liquid. Retire a chipped bowl -- a chip is a cut waiting to happen and cannot be cleaned reliably.
Plastic. Wash very hot with plenty of detergent. Baking soda paste for staining and odor. Never use an abrasive pad, which scratches the surface and makes the problem worse. The behavior mirrors how to clean silicone and metal spatulas.
Ceramic and stoneware. Usually glazed and easy to clean. A crazed or crackled glaze holds residue in the fine lines; if a bowl is badly crazed, treat it as decorative rather than food-use.
Copper. Traditional for egg whites. Wash with hot soapy water only, and clean tarnish with a mild acid and salt paste, rinsed thoroughly. Never leave acidic food standing in an unlined copper bowl.
Staining, odor, and stuck-on batter
Tomato, turmeric, and curry stain plastic bowls, and much of that is permanent. Washing immediately keeps it lighter. A baking soda paste lifts some. Staining is cosmetic.
Odor in plastic is usually held oil rather than the plastic itself. A very hot wash with plenty of detergent, then a baking soda paste, then a thorough rinse resolves most cases. If odor keeps returning in an old scratched bowl, the surface is too scored to clean reliably and the bowl should be replaced.
For dried batter or dough, fill the bowl with hot water and let it stand. Dried batter rehydrates and releases; scraping it dry usually just scratches the bowl. A silicone spatula lifts what is loosened without damaging the surface, and a whisk's ferrule needs its own attention afterward -- see how to clean a whisk.
Do not mix cleaning products to attack a stain. Bleach with ammonia, with any acid, or with alcohol produces dangerous gases, and peroxide and vinegar should never be combined in one container.
Drying and nesting
Nesting wet bowls traps water between them, which is how a stack develops spots and a stale smell in a cabinet.
Dry bowls with a towel or leave them inverted on a rack for twenty minutes before stacking. Stainless dries fastest; plastic and glass hold droplets in the base rim.
If your bowls have removable silicone base rings, store them refitted only when both parts are dry. Our house cleaning services page covers where kitchen equipment care fits into a full clean.
FAQ
Why does my plastic mixing bowl stay greasy?
Plastic's surface holds a thin fat film that lukewarm water will not release, and scratches from whisks and spatulas make it hold more. Wash in water as hot as you can safely handle with plenty of dish soap, and scrub with a brush rather than a sponge.
Can you whip egg whites in a plastic bowl?
It is not recommended. Trace fat retained by plastic interferes with the protein network that gives whipped whites their volume, and a bowl that feels clean can still carry enough to prevent a meringue forming. Use stainless, glass, or copper, washed in very hot soapy water first.
How do you clean under the silicone base ring on a mixing bowl?
Pull the ring off, wash both the ring and the recess underneath with hot soapy water and a brush, dry both fully, and refit the ring only when dry. That gap traps water and food and is one of the most common places for dark spots to develop.
How do you get dried batter out of a mixing bowl?
Fill the bowl with hot water and let it stand for ten to fifteen minutes so the batter rehydrates and releases, then wipe it out with a silicone spatula and wash normally. Scraping dried batter off dry usually just scratches the bowl surface.
When should a mixing bowl be replaced?
When glass or ceramic is chipped or badly crazed, when plastic is deeply scratched and holds odor after a thorough wash, or when a stainless bowl has a dent that keeps it from sitting flat. A surface that cannot be cleaned reliably is the practical test.
Bowls get used for everything and cleaned in a hurry. If you would rather hand the whole kitchen off, every home is different, so the real number depends on size, condition, and what you want covered. Get a quote and we will walk you through it.