Yes, it works
Best ratio: Use about half as much cornflour as flour — roughly 1 tablespoon of cornflour to thicken the same amount of liquid as 2 tablespoons of flour. Mix with cold water into a slurry first.
To use cornflour, always mix it with a little cold water first to make a smooth slurry, then stir that into the simmering liquid. Adding dry cornflour straight to hot liquid makes lumps. Once it’s thickened, don’t keep it at a hard boil for long, as prolonged high heat can break the thickening down.
When it works
- Thickening sauces, gravies, casseroles and fruit fillings.
- When you want a clear, glossy finish rather than a cloudy one.
- For a gluten-free thickener.
When it doesn't work
- As a 1:1 replacement in cakes and bread — cornflour has no gluten and won't give structure.
- In a roux-based sauce where you want that toasted-flour flavour.
- If boiled hard for too long after thickening, it can thin back out.
Taste & texture difference
Cornflour gives a glossy, almost translucent finish and a slightly silkier texture, with no raw-flour taste. Plain flour gives a more matte, opaque, 'homely' sauce.