Hard-ball stage

The hard-ball stage is a stage of cooking sugar syrup, reached at 121 to 130°C (250 to 266°F) at sea level. A drop of syrup in cold water forms a hard ball that holds its shape when you take it out. You can still change its shape a little with strong pressure, and it feels sticky. Nougat, marshmallows, divinity and some toffees are made with syrup at this stage. It comes after the firm-ball stage and before the soft-crack stage.

How to do it

1. Combine sugar, water and any corn syrup or glucose in a heavy, clean saucepan.
2. Stir over medium heat until the sugar has dissolved, then stop stirring.
3. Wash down the sides of the pan with a wet pastry brush to remove any crystals.
4. Clip on a candy thermometer so the tip sits in the syrup, not on the bottom.
5. Boil until the syrup reaches the temperature in your recipe, within 121 to 130°C (250 to 266°F).
6. Take the pan off the heat straight away and use the syrup at once. For marshmallows or nougat, pour it in a thin stream into whipped gelatin or egg whites while beating.

How to tell it is done

Drop a little syrup into very cold water and roll it into a ball. At hard ball, it is firm and holds its shape out of the water, but it is still slightly sticky and you can press a dent into it. If it flattens, it is not there yet. If it snaps into threads, it has gone past to soft crack.

Why it works

As syrup boils, water evaporates and the boiling point rises. At hard ball, only about 8 to 10 percent of the syrup is water. When it cools, there is too little water for it to stay soft, so it sets firm and chewy. Whipped into a foam, as in a meringue-based nougat, it holds a stable, firm shape.

Common mistakes

• Stirring after it boils. That can trigger crystals and a grainy result.
• Pouring hot syrup onto the beaters. It flings and hardens on the bowl. Pour down the side of the bowl instead.
• Not testing the thermometer. Check it in boiling water: it should read 100°C (212°F) at sea level. Adjust your target by the difference.
• Making candy on a humid day. The sugar absorbs moisture from the air and can turn sticky.

In recipes

"Cook to the hard-ball stage" or "cook to 125°C (257°F)" both mean this. Many recipes give only the number, so a thermometer is the easiest way to follow them.