{
    "id": 1070641,
    "title": "What is rock made of?",
    "slug": "what-is-rock-made-of",
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    "url": "https://sweeties.net/wiki/what-is-rock-made-of/",
    "modified": "2026-09-26T00:33:48+01:00",
    "excerpt": "Seaside rock is sugar, glucose syrup and water, boiled hard, then coloured, pulled and flavoured, usually with peppermint or spearmint. That is nearly all.",
    "content_text": "For such a colourful sweet, seaside rock has a very short list of ingredients. Almost all of it is sugar. The skill is in what the sugar boiler does with it, from boiling it hard to building the letters by hand.\nThe ingredients\nTraditional seaside rock is made from:\nGranulated sugar, the main ingredientGlucose syrup, roughly one part to every three parts of sugarWater, just enough to dissolve the sugarFood colourings, for the casing and the lettersFlavouring, most usually peppermint or spearmint\nThat is essentially it. Like other hard boiled sweets, rock ends up nearly 100 per cent sugar by weight, with only a tiny amount of colour and flavour and almost no water.\nWhat each part does\nSugar gives rock its sweetness and its hardness. Boiled to about 147 degrees Celsius, the hard crack stage, it loses nearly all its water and sets into a hard, glassy solid as it cools: see why is seaside rock so hard?\nGlucose syrup helps keep the sugar from forming crystals. In sugar glass, the brittle sugar used for fake windows in films, glucose or corn syrup is added for exactly that reason, so the sugar stays clear instead of turning grainy.\nWater is only there to dissolve the sugar at the start. Too little and the sugar can burn, or the finished rock can turn sugary and grain off. Nearly all of it is boiled away.\nColourings are mixed into small portions of the hot mixture on the cooling table, by hand, with a spoon or palette knife, to make the casing and the letters.\nFlavourings are poured in measured amounts into the mixture while it is being pulled.\nOne mixture, three parts\nEvery part of a stick of rock is made from the same boiled mixture, handled in different ways.\nThe centre is the mixture pulled on a machine with one fixed arm and two moving arms. Pulling works air into it and turns it from a solid golden mass into soft white.The letters are built from thin strips of coloured and white mixture. Each letter starts about the size of a thumbprint and is shrunk as the rock is stretched: see how do they get the letters in rock?The casing is coloured mixture, kneaded and rolled out with a rolling pin, then wrapped around the outside.\nThe whole assembly, called a boiling, is too thick to get your hands around. It is kept warm in a batch roller and then spun out, stretched into long, thin strings that are cut into sticks and wrapped: see how is seaside rock made?\nKeeping it hard\nBecause rock is so sugary, it pulls moisture out of the air if it is left unwrapped, and goes sticky and soft: see why does seaside rock go soft?",
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