Why Coffee Tastes Different in a Steel Tumbler

Bare stainless steel affects the taste, and the effect is worse with coffee than with water. Steel picks up and holds oils and aromas, and it contributes a faint metallic note of its own — which is why a flask that once held coffee makes tea taste odd for months afterwards. A ceramic lining is a neutral, non-porous barrier, so what she tastes is the coffee.

It keeps the insulation without the compromise. The vacuum wall doing the heat retention is unchanged; the ceramic is a thin interior surface. She gets a drink that is still hot two hours later and does not taste of the container.

A handle changes where it can be used. A handled mug is far easier to hold while doing something else and much less likely to be dropped, which suits a desk and a kitchen better than a smooth tumbler does — though it is worth checking against a car cupholder.

• A sister who commutes with coffee and has stopped enjoying it
• Anyone who has said flask coffee tastes wrong without knowing why
• Someone who alternates between coffee and tea in the same vessel
• A student or new graduate setting up a desk

• Fixes a specific complaint most people cannot articulate
• Insulation without the metallic taste
• Used every single morning

The things worth checking before you order — this is where gifts like this most often go wrong.

• Ceramic linings chip if treated roughly. Dropping it, or scouring the inside with anything abrasive, damages the surface that is the entire reason for buying it — a soft brush and washing-up liquid is the correct care.
• "Leak resistant" is not "leak proof", and the difference matters if it goes in a bag with a laptop. Read the exact wording rather than assuming, and test it over a sink before trusting it.
• Check the base against her car's cupholder if she drives. A handled mug with a wide base is the classic gift that turns out not to fit the one place it was wanted.
• Most vacuum flasks are hand-wash only, and dishwashers are what kill the seal and the exterior finish. Worth saying when you hand it over.