# What is formwork release oil?
**Formwork release oil, also known as mould release agent or form oil, is a chemical product applied to the inner surfaces of formwork before concrete is poured. Its primary purpose is to prevent the cured concrete from bonding to the formwork, allowing the panels to be removed cleanly without damaging either the concrete surface or the formwork itself. Using the right release agent is essential for achieving a smooth, defect-free concrete finish.**
## Application
Formwork release oil is applied as a thin, even coat to the formwork surface using a brush, roller, or sprayer. It should be applied shortly before the concrete pour — if applied too far in advance, the oil may dry out, run off, or collect dust, reducing its effectiveness.
There are several types of release agents available:
– **Neat oils** — traditional petroleum-based oils that form a barrier film between the formwork and the concrete. They are inexpensive but can leave stains on the concrete surface.
– **Chemical release agents** — react with the calcium hydroxide in fresh concrete to form a thin soap layer at the interface. These produce superior surface finishes and are the standard choice for architectural or fair-faced concrete.
– **Water-based emulsions** — environmentally friendly options that combine oil droplets suspended in water. They are less harmful to work with but may require more careful application.
– **Vegetable-based oils** — biodegradable alternatives made from plant oils, increasingly popular due to environmental regulations and worker health considerations.
When applying release oil, avoid using too much product. Excess oil can cause surface defects such as blowholes, discolouration, or retardation of the concrete surface. A properly applied release agent leaves the formwork surface with a barely visible, uniform sheen.
The choice of release oil also depends on the formwork material. Steel formwork, timber formwork, and plastic formwork each have different surface properties and may require different products for optimal results.
## Related terms
– Formwork
– Fair-faced concrete
– Blowholes
– Curing
– Surface finish
– Concrete
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