Caring for your ceramic mugs

A decent ceramic mug should outlast the person who bought it. Most do not, and the reasons are dull and preventable. Here is everything worth knowing, in the order it will actually matter to you.

The one thing that cracks mugs

Thermal shock. Ceramic expands when it heats. If one part of the mug heats much faster than the rest, the two parts pull against each other and something has to give.

In practice that means:

• Boiling water into a mug straight from an air-conditioned room or the fridge
• A hot mug set down on a cold granite or tiled counter
• A mug out of the microwave, rinsed immediately under a cold tap

The fix takes three seconds: warm the mug first. Swirl a little hot tap water around it, tip it out, then pour. This is the single habit that separates mugs that last a decade from mugs that crack in month four.

Sometimes the damage is invisible at first. You get crazing — a fine web of hairline cracks in the glaze, like an old painting. It usually is not dangerous, but it will trap tea stains permanently, and once it starts it does not stop.

Washing

By hand, which is what we would do

Warm water, a soft sponge, ordinary dish soap. That is genuinely it. The important part is what you keep away from it: never steel wool, never a scouring pad, never a powdered abrasive cleanser. They scratch the glaze, and scratched glaze is porous glaze — meaning every cup of coffee after that stains slightly more than the last.

In the dishwasher

Plenty of mugs survive the dishwasher fine. But two kinds should never go in:

• Anything with metallic trim — gold or silver rims degrade quickly under dishwasher detergent
• Hand-painted or decal designs — the pattern sits on top of the glaze rather than under it, and repeated hot cycles will fade or lift it

If a mug does go in, use the top rack. It is further from the heating element, and heat is what dulls glaze over time.

Getting tea and coffee stains out

That brown film is tannin. Soap does not shift it because it is not grease. Two things do, both of which are already in your kitchen.

Baking soda — for most stains

1. Make a paste: about a teaspoon of baking soda with a few drops of water
2. Rub it around the inside with your fingers or a soft cloth
3. Leave it five minutes, then rinse

It is very mildly abrasive, which is exactly enough to lift tannin without scratching glaze.

Vinegar — for stubborn rings

Fill with equal parts warm water and white vinegar, leave for thirty minutes, wash normally. Best for the hard ring at the waterline that baking soda skates over.

Do not use bleach. It is hard to rinse fully out of a porous surface, and this is something you drink out of every morning.

The microwave

Most plain ceramic is fine. The exceptions matter, though:

• Metallic trim will spark. Not "might" — a gold-rimmed mug in a microwave arcs, and can damage the oven as well as the mug
• An unglazed base absorbs water while it sits in the sink, and that trapped moisture turns to steam in the microwave. Occasionally it cracks the base

A useful test: if the mug comes out of the microwave hotter than the drink inside it, the ceramic is absorbing microwave energy rather than passing it through. Stop microwaving that one.

Storing them

Almost every chip we have seen happened in a cupboard, not in use. Two habits prevent nearly all of it:

• Do not stack mugs rim to rim. The rim is the thinnest, most exposed part, and the weight of the mug above it is enough to chip it
• Hang by the handle if you can. Hooks under a shelf keep mugs apart and let them dry properly

And dry them before they go away. A mug put away damp will smell faintly musty in a week, and that smell lives in the unglazed base where you cannot easily wash it.

When to let a mug go

A chip on the outside is cosmetic — keep using it. But retire a mug if:

• The chip is on the rim, where your lip goes. Sharp ceramic edges cut
• There is a crack right through the wall, not just glaze crazing. It will fail eventually, and it will be full of hot liquid when it does
• It weeps — you set it down and there is a damp ring even though the outside was dry. That means liquid is passing through the body

A cracked mug still makes a good pen pot or a home for a small plant. It just should not hold anything hot again.

The short version

• Warm the mug before pouring boiling water into it
• Soft sponge only — never anything abrasive
• Baking soda paste for stains, not bleach
• No metallic trim in the microwave or dishwasher
• Do not stack rim to rim, and dry before storing
• Retire it if the rim is chipped or it is cracked through

Do those and a good mug will genuinely last you years — which is rather the point of buying one you actually like.