Heatproof Mug
A heatproof mug is a handled cup of porcelain, stoneware or heat-resistant glass, usually holding about 250 to 350ml, made to take a drink just off the boil without cracking. It suits hot drinks too full for an Irish coffee glass: our Hot Buttered Rum and Tom and Jerry each come to nearly 300ml. It also takes ladled pots such as the Guy Fawkes Grog, Hot Spiced Cider and Spiced Rum Punch.
About the Heatproof Mug
What Makes a Mug Heatproof
Glass and ceramic fail under uneven heat. A drink just off the boil heats the inside wall at once while the outside is still at room temperature, and the strain between the two is what splits a cold mug.
Porcelain, bone china and stoneware mugs are made to take a drink from the kettle. Borosilicate glass expands far less with heat than ordinary soda-lime glass, the reason it is sold for hot drinks. Thin decorative glass, and any tumbler not sold as heat-resistant, should not take a hot drink.
Sized for Our Hot Drinks
Most mugs hold about 250 to 350ml to the brim. Our Hot Buttered Rum is 60ml of dark rum, about 50g of batter and 150ml of hot water: about 260ml. Our Tom and Jerry, an egg beaten into batter with 60ml of spirit and 120ml of hot milk, comes to about 280ml before its foam rises. Both want a mug of about 300ml.
That is more than an Irish coffee glass holds. The ladled pots pour less: the Guy Fawkes Grog 175ml a mug, the Hot Spiced Cider 150ml, or 200ml with its spirit, and the Spiced Rum Punch just under 200ml.
The heatproof mug beside other vessels for hot drinks
Heatproof mug
- Typical size
- About 250 to 350ml
- Material
- Porcelain, stoneware or borosilicate glass
- Our drinks
- Hot Buttered Rum, Tom and Jerry, ladled pots
Vintage Tom and Jerry mug
- Typical size
- Many around 180ml
- Material
- Milk glass or porcelain
- Our drinks
- Too small for our Tom and Jerry
Irish coffee mug
- Typical size
- About 200 to 250ml
- Material
- Heat-resistant glass
- Our drinks
- Irish Coffee, Hot Toddy, Hot Toffee Apple
Punch cup
- Typical size
- About 120 to 180ml
- Material
- Glass or porcelain
- Our drinks
- Mulled Wine, Fireside Punch
| Vessel | Typical size | Material | Our drinks |
|---|---|---|---|
| Heatproof mug | About 250 to 350ml | Porcelain, stoneware or borosilicate glass | Hot Buttered Rum, Tom and Jerry, ladled pots |
| Vintage Tom and Jerry mug | Many around 180ml | Milk glass or porcelain | Too small for our Tom and Jerry |
| Irish coffee mug | About 200 to 250ml | Heat-resistant glass | Irish Coffee, Hot Toddy, Hot Toffee Apple |
| Punch cup | About 120 to 180ml | Glass or porcelain | Mulled Wine, Fireside Punch |
The Tom and Jerry Set
Jerry Thomas, in 1862, kept the Tom and Jerry batter in a bowl and dealt each serving into a small bar glass with brandy and boiling water. The bowl later came with mugs to match: a ceramic bowl, the drink's name painted on its side, and small handled mugs. Milk glass sets were made in quantity in America from the 1940s to the 1960s.
Many of those mugs hold around 180ml. Ours uses 120ml of hot milk and fills about 300ml, so keep a vintage set for the table and share each drink between two of its mugs.
Warm the Mug, Keep the Drink Below a Boil
Run hot water into the mug while you build the drink and pour it away at the last moment. Pre-warmed, the mug is in no danger from the drink, and it holds the heat to the last sip instead of soaking it up.
Water for a single mug comes from a kettle rested half a minute off the boil. Milk, cider and punch are heated in the pan only until they steam. A boil costs the drink its spice and some of its alcohol, and in a Tom and Jerry it sets the egg into grains.
Washing and Wear
Give a hot mug time to cool before the washing-up bowl or the dishwasher. Porcelain and stoneware chip at the rim and where the handle joins; borosilicate glass shows a crack as a bright line against the light. Either is the end of its service with hot drinks.
Using the Heatproof Mug
Usage
Hot drinks of about 150 to 300ml: our Hot Buttered Rum and Tom and Jerry, each close to 300ml, and ladled pots such as the Guy Fawkes Grog, Hot Spiced Cider and Spiced Rum Punch. Rinse it hot before pouring, fill to a finger below the rim, and keep the drink at a steam, never a boil.
Pro Tip
Measure your mugs once with water to the brim. A mug that looks generous on the shelf often holds less than it seems, and a Tom and Jerry that reaches the rim before the milk is in has nowhere for its foam to go.
Professional Tips
- Run hot water into it while you build the drink, then pour that away.
- Rest the kettle half a minute off the boil; the drink itself only ever steams.
- Fill to about a finger below the rim for carrying.
- Hold a glass mug by its handle; the walls take the full heat of the drink.
Alternatives
Budget Alternative
A plain china mug from the kitchen cupboard. Measure it with water first: a 300ml mug takes any of our hot drinks.
Premium Option
A double-walled borosilicate glass mug. The air between the walls keeps the outside cool to hold and the drink hot for longer, and the glass shows the foam on a Tom and Jerry.
Specifications
Material
Porcelain, bone china, stoneware, or heat-resistant borosilicate glass
Capacity
Usually about 250 to 350ml; choose 300ml or more for our Hot Buttered Rum and Tom and Jerry
Details
A handle set clear of the body and a flat, steady base. Vintage Tom and Jerry set mugs are smaller, many around 180ml
More to explore
Common Questions
What size mug do you need for a Hot Buttered Rum?
What is a Tom and Jerry mug?
Can you put boiling water in a glass mug?
Is porcelain or glass better for hot drinks?
Can I use an Irish coffee glass instead?
Why warm a mug before a hot drink?
Can a heatproof mug go in the dishwasher or microwave?
What drinks are served in a mug?
Master the Technique
Made with the Heatproof Mug
Used In These Cocktails
Related Equipment
Guide by Jerry Can Spirits · Updated 11 October 2026