Castrol Rustilo Aqua 21
Soluble Corrosion Preventive Oil
Castrol Rustilo™ Aqua 21 (previously called Aquasafe™ 21) is a medium viscosity, mineral oil based product containing
film-forming additives and coupling agents, which is supplied as a concentrate for dilution with water prior to use.
After the evaporation of the water phase, the product leaves an ultra-thin, oily film on ferrous components.
Rustilo Aqua 21 is an inter-operational, short to medium term corrosion preventive which is used as an emulsion. It is
particularly recommended for protecting metal components from corrosion after other aqueous treatments.
Rustilo Aqua 21 can be applied by immersion and low pressure spray.
- Free from hydrocarbon solvents, complies with EC Solvent Directive (1999/13/EC)
- Heavy metals free (for example, Barium), which may help to fulfil aspects of legislative requirements and waste
treatment requirements that specify that these chemicals are excluded.
- Emulsion is stable up to 80°C (176 °F)
- Very good stability against inorganic salts. May be used even after applications where high levels of
contamination could be expected, e.g. subsequent to heat treatment or electroplating processes
- Excellent wetting properties
- Rustilo Aqua 21’s protective film can easily be removed by an alkaline cleaning process
|Metal type||Cast Iron, High alloy steel / Stainless steel, Low / Med alloy steel|
|Corrosion protection||Indoor Storage|
|Formulated without Boron||Yes|
|Formulated without Heavy Metal||Yes|
|Product type||Surface Treatments|
|Applicable to these sectors||Aerospace, Automotive Manufacture, Machinery, Metal Goods, Metals|
Always add Rustilo Aqua 21 to water (preferably at 30 – 35 °C (86 – 95 °F)) when making an emulsion.
As Rustilo Aqua 21 gives a semi-stable emulsion, it is beneficial to keep the fluid bath in constant circulation, for
example with a circulation pump, stirrer or by continuous component throughput.
Check concentration, pH and bath level regularly, especially if the emulsion is used hot.
The protective film must be completely dry before packaging.
In order to minimise the risk of any stability or corrosion issues caused by increasing levels of water hardness and
corrosive inorganic salts (i.e. chloride), it is recommended to top-up evaporation losses with deionised water.
The claims on film thickness and consumption are average values. These are valid for smooth surfaces with good
drain-off characteristics and simple geometries without holes or recesses.
(*) “Indoor storage” describes the storage of ferrous components in closed store-rooms having a relative humidity of
60%. The full corrosion protection can only be provided when the water is completely evaporated. Increased protection
times could be achieved by treating finished surfaces or storing the fully dried parts in a sealed pack.
(**) “Outdoor storage” describes open storage, which assumes primary protection from the elements by tarpaulin or
other form of cover.
To avoid product deterioration always keep the container / drum tightly sealed. For optimum product stability, store
between 5°C / 41°F and 45°C / 113°F in a cool, dry place away from direct sunlight. Prevent exposure to frost and avoid
water ingress. It is preferable to store the product indoors.
For more details, please refer to the Safety Data Sheet for this product.
This product was previously called Aquasafe 21. The name was changed in 2015.