What Is Rust? Introducing Rust Prevention Primers

One of the most frequent questions we are asked is how can I prevent an item from rusting. Below, we will discuss what is rust, and how you can easily prevent metalwork from rusting.

What Is Rust?

Rust Primer - What is rustWhen steel comes In contact with the atmosphere the moisture in the air causes the metal to corrode. This is known as oxidisation. The first signs of this corrosion are known as gingering.

Some paints available are what’s known as surface tolerant. This means that they are suitable for application over gingered steel without removing the oxidation. However, if the gingering is left without treatment, rust will quickly form.

The speed at which the steel will deteriorate will depend upon various factors. Factors include the type of steel, and the amount of moisture in the air. Consequently, the speed also is effected by if there are corrosive particles such as carbon dioxide or salt present in the air. The amount of moisture in the air is known as the relative humidity. Usually, it measured as a percentage. The higher the percentage of water in the air, the greater the saturation. Subsequently, this will create rust quicker.

A downside to a structure such as a bridge is that rust will weaken the metal. This makes these outdoor structures potentially dangerous. Rust also makes structure aesthetically unattractive. However, in recent years rusty looking buildings have become quite fashionable. For example, the recent redevelopment at Kings Cross in London has a stunning tower block with a rust effect. Have a look at the site here to find out more.

Introducing Promain’s Rust Primers

Below we have listed the different ranges of anti corrosive primers Promain offer. You can also see our full category of metal primers on our website here:


Anti-Rust & Metal Primers

There are a wide range of anti-rust metal primers available from Promain. The main ingredient that is used in paint to stop rust from forming is zinc.

Owatrol Oil - What is rustIf you do not want to apply a paint coating to the steel then the application of Owatrol Oil will help. Owatrol Oil will soak into the steel pushing out the moisture out. This will prevent the steel from oxidizing or rusting. after application, a paint topcoat is not always necessary. Owatrol Oil can be added to metal primers to enhance their anti rust qualities. 

However, most zinc anti-rust primers will need application of  topcoat of paint to prevent further moisture absorption.


Waterbourne and Solvent Based Anti-Corrosive Primers

Anti-rust and metal primers are available as either solvent or water based. Different solvents are used to suspend the paint solids. Solvents typically include xylene, cellulose or white spirit.

We do not recommend to apply strong (hot) solvents such as xylene over a weak solvent. Weak solvents include white spirit or water based paints. Strong solvents typically are less environmentally friendly than water based paints. They also produce fairly strong odours and the emission of VOCs. Their Volatile Organic Compounds is much higher than waterbourn paints.

Simply refer to the manufacturers product data sheets for information on a paints VOC level. 

Ferrous and Non-Ferrous Metals

Find out the metal type before you apply a anti rust primer. Anti-rust agents act differently. Some work only on certain ferrous metals. Ferrous metals include cast iron, iron, steel. Others include copper, brass, lead. There are however general compatible products available.  

Anti-Rust Paint

Finally, rustproofing products are available as either a primer or a topcoat. However, products such as Rustoleum CombiColor is an anti rust primer and topcoat in one.

Applying an all in one paint is a good time saver. However, we still recommend applying 2 coats of paint to any metal surface. The reason for this is it is extremely easy to miss areas or apply a thin coat. If this happens, it will allow the water to easily penetrate the paint and rust can form.

Rust-Oleum 769 - what is rustPromain’s recommendation is to firstly apply a good quality anti-rust primer such as Rustoleum 769. Rust-Oleum 769 Damp Proof Primer is a Anti-Rust Metal Primer. It is developed for application on hand tool prepared sound rusted steel surfaces. Although primarily intended for brush application, you can also apply it by roller or spray.

If applied on damp surfaces, the unique fish oil formulation will drive out trapped moisture and air. This will prevent rust formation beneath the paint layer. 

Cold Galvanizing

There are a range of cold galvanizing paints available. Options include Rust-Oleum Galva Zinc, Fosroc Galvafroid and Zinga. They all work in very similar methods.

zinga what is rustOne of the products is Zinga 96%. You could apply this prior to applying a topcoat. Zinga can stop rust for up to 20 years if you apply it to a properly prepared surface. Galva Zinc, Galvafroid and Zinga are the cold equivalent of hot dip galvanizing.

They are revolutionary products that are ideal for metal that cannot be dipped. Customers tend to use these systems on car chassis and awkward metalwork. All 3 products, have a life expectancy on correctly prepared steel of 25 years. You can see the certification documents here for Zinga.

In Conclusion

To sum up, preparation is the most important part of any job. There is a reason why some paints are cheaper than others. You always get what you pay for. Promain always recommend a discussion prior to cutting corners. Rust preventative systems can be durable and effective if you apply and prepare correctly.

Contact Promain today for further information on 01462 421333.

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