Sugar stages: thread, soft ball, hard crack
Intermediate Kitchen science
As sugar syrup boils, its temperature tells you how much water is left, which decides whether candy sets soft, chewy or glass-hard.
Written with AI help from the sources listed, and published by Cory. Spot a mistake? Tell us and we'll fix it.
How do you do it?
- Use a candy thermometer: thread 223-235°F, soft ball 235-245°F, firm ball 245-250°F, hard ball 250-265°F, soft crack 270-290°F, hard crack 300-310°F.
- Test the thermometer in boiling water first and adjust targets by the difference from 212°F.
- Brush the inside of the pot with a wet pastry brush to wash down sugar crystals.
- Stop stirring once the syrup boils unless the recipe says otherwise.
- No thermometer: drop syrup into ice water and see if it forms threads, a soft ball or brittle strands.
Why does it work?
Sugar dissolved in water boils at a higher temperature as the water boils off, so the temperature is a precise reading of how concentrated the syrup is. At soft ball, there is still about 15 percent water, enough for fudge and fondant to stay soft. By hard crack, only about 1 percent remains, and the sugar cools into a hard glass, as in brittle and lollipops. A concentrated syrup is unstable and wants to recrystallize; one stray crystal, too much stirring or a grain on the pot wall can turn it gritty. A little corn syrup, honey or acid adds other sugars that get in the way of crystals.
What are the common mistakes?
- Walking away near the target — syrup climbs the last few degrees fast and overshoots.
- Stirring boiling syrup — encourages crystals and grainy candy.
Still stuck? Watch someone do it on YouTube.
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