Many people think that galvanized metal products (roofing and fence of galvanized corrugated sheeting, pipes, etc.) absolutely do not need additional treatment with paint compositions.
But this is not quite true, after a certain period of time there is a need for painting even protected by zinc metal products, especially when it comes to roofing materials because they are constantly under the influence of precipitation.
Let’s take a look at what arguments there are in favor of doing this work and what galvanizing paint can be used.
Why paint galvanized steel?
A zinc layer protects the steel from the negative effects of the environment. Thus galvanization extends the shelf life of the material, but regardless of that over a period of time zinc loses its quality as well.
With time a so-called “white rust” appears on the zinc-coated surface, which destroys the zinc coating. That’s why it is necessary to paint galvanized metalware. Thus it is possible to avoid possible deterioration of the material.
There is one more advantage of painting galvanized surfaces. It’s a nice look the paint gives to the coating.
How to choose the paint composition?
Painting a metal surface is not difficult, it is much more difficult to choose the right paint. There is a special galvanizing paint that is also used to paint steel and aluminum. The different paint formulations differ from each other in their constituents and therefore have different performance properties.
Today the most common types of protective compositions for galvanized surfaces are:
- Acrylic emulsions
- Alkyd based paints
- Vinyl paints
- Rubber paint compositions
Acrylic staining compounds
As a paint for galvanized metal, acrylic compounds have many distinctive properties. Acrylics are based on an organic solvent, but there are also waterborne dyes. The paint also has anti-corrosion additives, so it’s great for metal. Generally, acrylic paint gives the coating a matte finish.
The positive qualities of such paints include:
- Long shelf life
- Resistant to changes in atmospheric pressure and to sunlight, which it can be used when painting external parts
- It has water-repellent properties
- Relatively low cost
- High adhesion to the material
This coating has quite good quality indicators. Such a paint composition creates glossy shades. It also has an anti-corrosion pigment, due to which the coating is preserved for quite a long time. It is worth noting that as a paint for galvanizing on an alkyd basis is often used in areas with a maritime climate.
Vinyl coating is gaining in popularity with each passing day. This painting is superior to its “opponents” in many ways. The first thing worth mentioning is the high resistance of the coating to changing weather conditions. This quality acts as a significant advantage.
Another advantage is the high tolerance for temperature fluctuations. However, along with all this is a disadvantage – a relatively high cost.
Rubber paint compound
Such paint is made on the basis of acrylic. It attracts customers with its elasticity. By painting the surface in several layers, it is possible to create a tangible rubber coating. Therefore, such a surface will retain its protective function in all conditions.
There are several main qualities of rubber paint:
- Good water-repellent qualities.
- Rubber is resistant to atmospheric changes.
- It has a high shelf life.
- Complete absence of harmful substances, hence the environmental friendliness of the coating.
In order to paint metal with your own hands brought the desired result, you should carefully study the instructions on the container with the LCM and clearly adhere to it, then the treated surface will be able to maintain a good appearance for a long time.
Preparing to paint
Before you start painting galvanized rolled metal products, it is necessary to prepare the surface to be treated well. In particular, it is necessary to perform the works enhancing the adhesion of zinc coating.
In order to paint evenly and densely on a galvanized surface, the paint should soak and get into its natural micro deformations. If there are few or no such micro deformations it is necessary to create them artificially. Often the treated surface is coated with an abrasive substance for this purpose.
There is another good way – if the galvanized surface (in particular the roof) for a long time was in contact with the air – half the job is done, because for one year the fresh zinc, or rather its surface has time to react with oxygen, while covered with a layer of oxide, which perfectly absorbs the paint. But nevertheless, even such zinc should be lightly cleaned and degreased with a solvent.
When choosing any materials for painting a roof or other galvanized surfaces it is better to pay attention to abrasives, primers, paints, and solvents of one and the same company because the chemical components in them are specially selected for joint use.
Creating a protective layer on the surface
If the zinc surface was previously coated with a layer of paint, you should clean it from the remains of these materials. The best way to do this is to use solvent and a metal brush. This work should be done carefully, as it is not desirable to remove the layer of zinc along with a layer of paint from the roof.
After that, again, it is necessary to clean the surface of the resulting residual dirt. To do this, you can use an alkaline detergent.
Painting galvanized metal
Immediately before application, the paint agent should be thoroughly stirred and poured into a special tray. It is best to apply a thin coat of paint by roller, brush or sprayer. Allow the previous layer to dry before applying a new one.
The optimum is to paint in two coats. But to achieve the best result, when the color of the paint will shine in richer shades, and the coating itself will have strong protective properties, you can apply three coats of paint material.
Protective equipment and precautions
Do not forget that toxic and flammable substances are used in the work, for this reason, it is necessary to prevent any possibility of contact of the paint with open flames. It is strictly forbidden to smoke in the vicinity. If the work is carried out in an enclosed area, care must be taken to ensure that it is adequately ventilated during and after the work.
If there will be a large amount of such work on a large surface area to be painted – get a respirator to protect your respiratory system. Don’t forget to wear special clothing, gloves, and comfortable shoes.