Carbonation and highballs

A highball is the most honest drink in the bar. Two ingredients, nowhere to hide, and a clock running from the moment the soda leaves the bottle. Carbon dioxide wants to escape; warmth, agitation and rough surfaces help it. Your job is to slow it down.

What you need

• A highball glass, 8 to 10 oz (240 to 300 ml), kept in the freezer
• The spirit, kept in the freezer for at least two hours
• Small glass bottles of soda or tonic, unopened, in an ice bath or the coldest part of the fridge
• One large clear cube or a Collins spear, tempered 2 to 3 minutes out of the freezer
• A barspoon
• For home carbonation: a soda siphon, or a whipper rated for CO2, with the matching chargers, and the manufacturer's manual

Why soda goes flat

Cold water holds more dissolved CO2 than warm water. Every warm surface the soda touches, every bubble nucleation point (pulp, ice fractures, scratches in a glass), and every stir releases gas. Dave Arnold's rule, relayed through Punch, is that colder drinks hold more CO2 without foaming and lose less when served. Buy small bottles: a 1 liter bottle opened three times is flat by the third pour. Glass bottles hold pressure better than plastic over weeks on a shelf.

Steps: the house highball

1. Measure 1.5 oz (45 ml) of freezer-cold spirit into the frozen glass. For a Japanese highball use Japanese whisky; for a gin and tonic, gin.
2. Add the ice: one large cube or spear, tempered so it does not crack.
3. Tilt the glass and pour 4.5 oz (135 ml) of cold soda down the inside wall. That is the 1:3 ratio. For tonic, Arnold's own pour is closer to 1:2 (3.25 oz of tonic in a 5 oz drink, which leaves about 1.75 oz of gin) because tonic carries sugar and quinine; start at 1:3 and tighten to taste.
4. Dip the barspoon to the bottom once and lift it out. That is the whole stir. Garret Richard's Punch method puts it plainly: stir everything except the soda, and after the soda, barely touch it.
5. Express a citrus peel over the surface and drop it in, or squeeze a lime wedge for a gin and tonic. Serve at once.

For a highball with more than two ingredients (a mojito-style build, or a French 75 with lemon and syrup), stir the spirit, citrus and syrup in a tin first, pour ice and three-quarters of the sparkling component into the glass, add the tin's contents, then top with the rest.

Home carbonation

Two tools suit a home bar. Both need everything cold and the liquid clear; pulp, oils and fat are nucleation points that foam and go flat.

Soda siphon (for water, or clarified low-sugar mixes):

1. Fill with cold water to the siphon's measuring tube or fill line, never above it. iSi's siphon manual gives a maximum of about 1 liter and says water only, no added ingredients.
2. Screw on the head, fit one CO2 soda charger made for that siphon (the manual allows exactly one), and tighten until you hear the gas enter. Do this away from other people and keep your face away from the siphon.
3. Shake at least 5 times. Refrigerate at least an hour before using. It keeps for days.

Whipper method for a full cocktail (from Angelos Bafas via Punch):

1. Batch the drink with dilution built in. For a long drink, add water equal to the soda in the classic recipe, for example 3 oz (90 ml) water in place of 3 oz soda in a mojito; Noel Venning's range is 3 to 10 percent added water for shorter drinks.
2. Chill the liquid, the whipper and the CO2 bulbs. Fill through a funnel to no more than the rated capacity.
3. Charge with one CO2 bulb, then hold the whipper upright and press the lever to vent. This purges air.
4. Charge with a second bulb, shake hard for a few seconds, and rest upright in the refrigerator for up to 24 hours so the gas integrates.
5. Before opening: press the lever to vent fully, then unscrew the head and pour gently over ice.

Pressure-vessel safety

• Use only the chargers the manufacturer specifies for your device, and never more than the stated number; iSi's soda siphon takes one iSi soda charger. Use CO2 for carbonation. N2O is for cream and infusion, not fizz.
• Never fill above the line. The manual's reason is plain: overfilling or over-charging can push the vessel past its rated pressure (16 bar for the iSi siphon).
• Keep the vessel inside its rated temperature range. The iSi siphon is rated for 1 to 30 C (34 to 86 F): never heat it, never leave it in a hot car, and never store it in a freezer.
• Vent before opening, every time, and never unscrew the head while the vessel is pressurized. If the pressure will not release, stop and contact the manufacturer's service center rather than forcing it.
• Retire a siphon that has been dropped, dented or cracked; the manual says to have it checked by the service center. Never mix a head and bottle from different models or brands, and screw the head and charger holder on straight and fully tight, never crooked.
• Keep the siphon and chargers out of children's reach, and dispose of empty chargers with metal recycling.
• Read the manual that came with your device. The figures above are from iSi's soda siphon manual; your own model's data sheet takes precedence.

What can go wrong

• Flat on arrival: warm glass, warm spirit, or soda opened earlier. Freeze and buy small.
• A geyser when the ice goes in: ice straight from a cold freezer; temper it. Or the glass is scratched; retire it.
• Foam that will not settle in the whipper: pulp or fat in the batch. Fine strain, or let juice settle overnight and decant.
• Tastes watery: too much dilution in the batch, or a small cube melting fast. Use one large piece of ice.
• Tastes sharp and thin: the 1:3 pour is too long for a low-sugar soda. Try 1:2.5.

Responsible-service note

Highballs drink quickly and taste light. A 1.5 oz pour of a 40 percent spirit is one standard drink by the US definition, however tall the glass. Offer water alongside and let the guest set the pace.

Sources

• Punch, Kara Newman, "Whoops, We've Been Making Highballs All Wrong" (2023), with Garret Richard.
• Punch, Justin Burnell, "For Dave Arnold, No Ordinary Gin & Tonic Will Suffice" (2024).
• Punch, Tyler Zielinski, "A Better Way to Batch and Fizz" (2021), with Angelos Bafas and Noel Venning.
• iSi, "Soda Siphon instructions for use", Siphon Data and Safety Information.