Why chocolate will not release from the mould
Release is caused by contraction, and contraction is caused by temper. A piece that will not come out was never in temper.
If you read nothing else
Release comes from contraction and contraction comes from temper. Chill briefly to force it, never prise with a knife, and never wash a polycarbonate mould in detergent.
Contraction is the mechanism
Form V cocoa butter crystals are denser than the liquid they formed from, so properly tempered chocolate physically shrinks as it sets. That shrinkage pulls the piece away from the mould wall, and it is visible: a set mould shows a faint gap at the edges of each cavity.
Untempered chocolate does not contract meaningfully, so it stays in contact with the mould and grips it. That is the whole explanation for the great majority of release failures.
The other causes
A scratched or greasy mould grips even well-tempered chocolate. Polycarbonate moulds are cleaned with cotton wool and never washed with detergent or put in a dishwasher, both of which damage the surface permanently.
Setting too warm is the third: the chocolate needs a cool room to complete its contraction, and at 26°C it never fully does.
What to do now
Chill the mould briefly — ten to fifteen minutes, no more — which forces some contraction and often releases the pieces. Then invert and tap firmly on a padded surface.
Do not prise pieces out with a knife. They will break, and the mould will scratch, which turns a batch problem into a permanent equipment problem.
If they still will not come out, warm the mould very slightly, melt the chocolate out, and re-temper. Nothing is lost but time.
Covered in this guide
- Moulding chocolateThe method, including how moulds are actually cleaned.
- TemperingThe crystallography that produces contraction.
- Making filled chocolatesThe filled-chocolate context where release matters most.
Sources
- ChocolateHQ editorial synthesis — ChocolateHQ(citation identity confirmed; passage not re-read)
- The Science of Chocolate — Royal Society of Chemistry(citation identity confirmed; passage not re-read)