A frozen glass looks generous and does the beer no favours. Ice crystals knock the head flat, the cold mutes everything the malt is doing, and the first third of the pour tastes of nothing at all.

What the cold hides

Aroma needs a little warmth to leave the liquid. Serve a lager at freezing and you get carbonation and not much else, which is fine if the beer has nothing to say and a waste if it does.

What the ice does to the head

A frosted glass is wet, and that water is frozen. It melts into the beer as you pour, thins the foam and leaves a head that collapses before you have sat down. The lacing goes with it.

What to do instead

Rinse the glass with cold water and pour straight away. The film of water helps the head form and stops the beer clinging to the sides. That is the whole trick, and it is why every glass behind our bar goes under the rinser first.