When 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 is known as gingering. Below, Promain’s technical team would like to introduce anti rust paint for protection of a wide range of metals in both commercial and domestic environments.
Explaining Rust Paint
Some paints can be known as surface tolerant. This means that they are suitable for application over gingered steel without removal of any oxidation. If the gingering is left without treatment however, rust will quickly form. The speed at which the steel deteriorates will depend upon a range of factors. These factors will include type of steel used in manufacturing, the amount of moisture in the air, and if there are corrosive particles such as carbon dioxide or salt present if there are chemicals in the air. The amount of moisture in the air is known as the relative humidity and is measured as a percentage. The higher the percentage of water in the air the greater the saturation this will create rust quicker.
A downside to a structure such as a bridge is that rust will weaken the metal making outdoor structures potentially dangerous. Rust can also make structure aesthetically unattractive.
Promain’s Anti-Rust & Metal Primers
There are a wide range of anti-rust metal primers available from Promain. The main ingredient used in paint to stop the formation of rust is zinc.
If you do not wish to apply a paint coating to the steel, then the application of Owatrol Oil will soak into the steel pushing out the moisture out preventing the steel from oxidizing or rusting. Once Owatrol Oil has been applied a paint is not always necessary. Owatrol Oil can be added to metal primers to enhance their anti rust qualities.
However, most zinc anti – rust paint primers will need to have a topcoat of paint applied to prevent further moisture from being absorbed making the metal rust further.
Water Bourne and Solvent Based Rust Paint Primers
Anti- rust paint and metal primers are available in either solvent or water based formulations. Solvent based paints use various chemicals to suspend the paint solids. This usually includes xylene, cellulose or white spirit. The application of strong (hot) solvents such as xylene over a weak solvent such as white spirit or water based paints is not recommended. Strong solvents typically are less environmentally friendly than water based paints. They also produce fairly strong odours and the emission of VOC’s – Volatile Organic Compounds is much higher than water bourn paints. If you refer to the manufactures data sheets information on the VOC levels are available. This is important if you are painting in an enclosed environment or around food.
Do I Have A Ferrous and Non-Ferrous Metal?
This is a question you need to determine before applying an anti rust paint primer. Anti-rust agents act differently, some only on ferrous metals – cast iron, iron, steel – others on copper, brass, lead. There are however rust paints that are compatible for many metals available.
Promain’s Anti Rust Paint
Finally, rustproofing products are available as either a primer or a topcoat. There are however paints such as Rustoleum CombiColor that is an anti rust primer and topcoat in one. Applying an all in one paint is a good time saver though 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. This will allow the water to easily penetrate the paint and rust can form. Promain’s technical recommendation is to apply a good quality anti-rust primer such as Rustoleum 769.
Rust-Oleum 769 Damp Proof Primer is a anti-rust metal primer that is developed for application on hand tool prepared sound rusted steel surfaces. Although primarily intended for brush application, roller or spray are also acceptable. If applied on damp surfaces, the unique fish oil formulation will drive out trapped moisture and air, preventing rust formation beneath the paint layer.
Zinga Cold Galvanising Paint
Another option is Zinga cold galvanising paint before applying a topcoat. Zinga can stop rust for up to 20 years if applied to a properly prepared surface. Zinga Film Galvanising System is a single pack coating that contains 96% zinc to provide cathodic protection of ferrous metals. This paint can be used as an alternative to hot-dip metallisation, as a primer in a duplex system (active and passive) or as a recharging system for hot-dip galvanisation, metallisation or zinganised surfaces, Zinga can be applied on site, avoiding the need for dismantling ferrous metal structures, forming a grey matt, non toxic finish. Zinga conforms to ISO standard 3549 in regard to its zinc purity of 99.995% and to ATM standard A780 in regard to its use as a repair coating for hot-dip galvanisation. Zinga is overcoatable with a compatible paint.
We have a series of articles to help you understand more about cold galvanising:
- Using Zinga Cold Galvanising On A Narrowboat
- Boat Hull Cold Galvanization Using Zinga
- Protecting A Classic Car Chassis With Zinga
To find out more about Promain’s range of rust paints, anti rust primers and corrosion protection, view our shop categories below:
To sum up, preparation is the most important part of any paint job. As always Promain recommend a thorough read of your chosen products product data sheet prior to application. Within these sheets, you will find how preparation should be performed with any pitfalls. If you have any questions in regards application or preparation, contact our technical team. This is important before an expensive or time consuming mistake could occur.
Always remember there is a reason why some paints are cheaper than others. You will always get what you pay for at Promain!