Mug care is not one-size-fits-all. The way you clean, heat, and handle a mug depends on whether it is made of ceramic, glass, or stainless steel. Each material reacts differently to temperature changes, detergents, and everyday wear. This guide walks you through the specific care steps for stoneware and ceramic mugs, glass mugs, and vacuum-insulated stainless steel mugs, using manufacturer instructions and independent safety guidance. For a broader look at cleaning and stain removal, see our how to clean coffee mugs article.
| Material | Do | Don’t |
|---|---|---|
| Stoneware / Ceramic | Preheat oven before use; place hot mug on dry potholder or cooling rack; use the vented lid as directed; use plastic or nylon cleaning pads and non-abrasive cleanser. | Use on stovetop, broiler, or open flame; add liquid to hot stoneware; microwave empty; use abrasive cleaners or metal scouring pads; soak for extended periods; attempt to repair cracks. |
| Glass | Place hot glass on dry cloth potholder; preheat oven fully; cover dish bottom with liquid before cooking meat or vegetables; inspect for chips, cracks, and scratches. | Use on stovetop or under broiler; add liquid to hot glass; take directly from freezer to oven; place hot glass on cold or wet surfaces; use browning elements in microwave. |
| Stainless Steel (Insulated) | Hand wash with neutral dish detergent and lukewarm water; dry thoroughly; use oxygen bleach for interior tea stains; soak gaskets in diluted bleach for stains (except lid/stopper body). | Use chlorine bleach on main body or stopper; use abrasive cleansers, steel scrubbers, or polishing powder; use a dishwasher or dish dryer (Thermos excepts only the gaskets); use paint thinner or benzine. |
Caring for Ceramic and Stoneware Mugs
Stoneware mugs, like the CorningWare Meal Mug, are durable but can break if exposed to extreme heat or rapid temperature changes. CorningWare’s use and care instructions for its stoneware products warn against using them on any direct heating source, including stovetops, broilers, grills, and open flames. The company also advises against using stoneware in toaster ovens, air fryers, slow cookers, or pressure cookers unless specifically noted. CorningWare says the Meal Mug’s vented lid controls steam and splatters in the microwave.
To avoid thermal shock, CorningWare says you should never add liquid to hot stoneware, microwave an empty mug, or transfer a mug directly from the freezer to a hot oven. The safest place for hot stoneware to cool is on a cooling rack, dry potholder, or dry cloth. Do not place it on a metal stove grate, in a sink, or on a wet or cold surface. When cleaning, use only plastic or nylon pads and non-abrasive cleansers. Avoid soaking stoneware for extended periods, and never attempt to repair a cracked mug, as it can eventually break. For more on ceramic mug types, see our ceramic mugs page.
Caring for Glass Mugs
Glass mugs and kitchenware are valued because they do not leach hazardous materials into food, but they are vulnerable to thermal shock. According to a 2019 Iowa State University Extension blog on glass kitchenware cautions, thermal shock occurs when glass undergoes a drastic temperature change, causing it to fracture. Modern glass mugs are often made from tempered soda-lime glass, which handles impact better than older borosilicate glass but is less resistant to rapid temperature swings.
Iowa State Extension relays several precautions originally published by Consumer Reports in 2010. Always place hot glassware on a dry cloth potholder or towel, never on a cold or wet surface. Allow the oven to fully preheat before placing glass inside, and cover the bottom of the dish with liquid before cooking meat or vegetables. Do not add liquid to hot glass, and avoid taking a glass mug directly from the freezer to the oven or vice versa. When using a microwave, do not use browning elements. Inspect glass mugs regularly for chips, cracks, and scratches, and discard any with such damage. For more on glass mug options, visit our glass mugs overview.
Caring for Stainless Steel Insulated Mugs
Vacuum-insulated stainless steel mugs, like the Thermos JNR model, keep drinks hot or cold for hours but require careful cleaning to maintain their performance. The Thermos instruction manual for the JNR mug emphasizes hand washing with a neutral dish detergent diluted in lukewarm water. After washing, all parts must be drained and dried thoroughly to prevent water spots or rust. The exterior should be wiped with a dry cloth immediately after washing.
Thermos prohibits using chlorine bleach on the main body or stopper, as it can cause rust or damage. Only the gaskets, spout, and lid cover may be soaked in diluted bleach for stain removal. For tea stains inside the main body, Thermos recommends using oxygen bleach for about 30 minutes, or a mixture of lukewarm water and vinegar (10% vinegar) for rust specks, or citric acid (1-2%) for gritty residue. Never use paint thinner, benzine, steel scrubbers, polishing powder, or abrasive cleansers. The manual says not to use a dishwasher or dish dryer, except for the gaskets. For more on insulated mugs, see our insulated mugs page.
Inspecting for Cracks and Chips
Regular inspection is part of mug care. CorningWare’s stoneware instructions explicitly state: “Do not attempt to repair when cracked.” A cracked stoneware mug can break unexpectedly, especially when heated. Iowa State Extension’s glass kitchenware cautions similarly advise discarding glass dishes with chips, cracks, or scratches. For stainless steel mugs, check that gaskets are not worn or deformed, as Thermos notes that worn gaskets can cause leaks. If a gasket is stained or moldy and cannot be cleaned, Thermos recommends disposing of it and purchasing a replacement.
Decorative Ceramics and Lead Concerns
Not all ceramic mugs are intended for food use. The FDA warns that lead used in pottery glazes may leach into food, particularly from traditional pottery and decorative ceramicware. The agency states that there are no FDA regulations authorizing lead as a color additive or food additive, including in foodware. If you have a decorative or handcrafted ceramic mug, check whether it is labeled as food-safe. The FDA advises that lead exposure is a health concern, especially for children, and that consumers should be aware of the potential for lead leaching from certain imported or traditional pottery. For everyday use, stick to mugs that are clearly marked as food-safe.
Safety Around Hot Drinks
Hot beverages can cause serious scalds. The American Burn Association advises keeping hot drinks away from table and counter edges and using travel mugs with tight-fitting lids to reduce spill risks. When handling a hot mug, always use a dry potholder or cloth, as wet or cold cloths can cause thermal shock in ceramic or glass, and can also lead to burns if the mug slips.
Checklist for Everyday Mug Care
- Read and save the manufacturer’s care instructions for your specific mug.
- Inspect mugs before each use for cracks, chips, or worn gaskets.
- Hand wash insulated stainless steel mugs with mild detergent and dry immediately.
- For stoneware and glass, avoid sudden temperature changes: preheat ovens, never add liquid to hot surfaces, and cool on dry, heat-safe surfaces.
- Use only non-abrasive cleaners and soft sponges on all mug materials.
- Discard any mug with cracks or deep scratches; do not attempt repairs.
- Ensure decorative ceramic mugs are labeled food-safe before using for beverages.
For more detailed guidance on cleaning methods, see our mug cleaning page. If you are dealing with stubborn stains or odors, our odor and stain removal guide can help.
Frequently asked questions
Can I put my stoneware mug in the microwave?
Yes, if the manufacturer says it is microwave-safe. CorningWare’s stoneware Meal Mug is microwave-safe, and its vented lid is designed to control steam and splatters. Never microwave an empty stoneware mug, and avoid microwaving a tiny amount of food, as this can cause overheating and breakage.
Why did my glass mug shatter when I poured hot coffee into it?
Glass can shatter from thermal shock when it experiences a rapid temperature change. Iowa State University Extension explains that placing hot glass on a cold or wet surface, or adding hot liquid to a cold glass, can cause it to fracture. Always warm the glass gradually or ensure it is at room temperature before adding boiling liquids, and place it on a dry cloth or trivet.
How do I remove tea stains from my stainless steel travel mug?
Thermos recommends using oxygen bleach for tea stains inside the main body. Soak the interior with oxygen bleach for about 30 minutes, then rinse and dry thoroughly. For the gaskets and spout, you can use diluted chlorine bleach, but never use chlorine bleach on the main body or stopper, as it may cause rust or damage.
For a complete overview of care by material, visit our care by material category page. You can also explore our main mug care section for more topics.
