Rock Candy: Sugar Crystal Growth (3D)

Syrup Jar

Sugar concentration 2400 g/L

Syrup temperature 25°C

Agitation (stirring) 20%

Seed crystal size 1.0 mm

Time compression 0.6 days/s

Crystal Readout

Supersaturation S

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Growth rate

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Simulated time

0.0 d

Clarity

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How it works

Sucrose's solubility rises steeply with temperature, so a syrup boiled hot and then cooled becomes supersaturated: it holds more dissolved sugar than the cooled solution can normally keep in solution. That excess drives real crystallization, expressed here as S = C / C_sat(T) — sugar concentration over the temperature-dependent solubility limit. When S > 1, dissolved sucrose molecules deposit onto the seed crystal's monoclinic lattice faces; when S drops below 1 (raise temperature or dilute), the crystal slowly re-dissolves instead.

Growth is genuinely layer-by-layer and face-specific, not fractal branching: each of the crystal's three independent axes accretes at its own fixed rate ratio (real sucrose crystals are elongated monoclinic prisms, never six-fold symmetric like ice), scaled by supersaturation to a nonlinear power (steep, BCF/2D-nucleation-like kinetics) and by a stirring term — agitation thins the depleted boundary layer around the crystal, resupplying sugar faster. Push S and stirring too high, though, and the surface can't order itself properly: growth outruns diffusion, trapping mother liquor and defects, which this model renders as rising cloudiness and a rougher, less faceted surface — the same real trade-off candy-makers manage by growing rock candy slowly and undisturbed.

Drag to orbit, scroll to zoom.
Click empty syrup, or the "Dip new seed string" button, to lower another string with its own seed crystal into the same jar.

t = 0.0 days · crystals = 1

Drag to orbit · scroll to zoom · click syrup to dip a new string

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Rock Candy: Sugar Crystal Growth — 3D Sucrose Crystallization Simulator