Painting a galvanized sheet roof or wall allows you to change its image and helps the material last longer. We tell you how to do it step by step.
Thanks to its strength and durability, the galvanized sheet has become a very convenient option in construction in recent years. It is a noble surface, which we can embellish by adding an attractive colour finish. We tell you how to paint a galvanized sheet so that your house gains in quality and beauty.
These sheets, which were previously used almost exclusively in the elaboration of metallic structures, in urban furniture and civil works, are increasingly used as finishing and aesthetic cladding in homes and buildings. It is very common to see them on ceilings, on doors, gates and even as a more avant-garde decoration element in exterior wall cladding.
How To Paint Galvanized Sheet
You have to bear in mind that galvanized sheet is a steel sheet that is coated on both sides with a layer of zinc. To do this, the steel is immersed in a zinc crucible, which makes the sheet coated with this metal, creating the protection that prevents the development of iron oxide.
Therefore, while painting galvanized steel sheets is a simple task that works very well, this protection procedure raises some fundamental issues that must be taken into account for the application of paint on the sheet to be successful.
Prior verification of the surface
Before starting, it is necessary to check that the sheet has sufficient adhesion so that the work lasts. For this, you have to check these questions:
- ♦The adhesion of the paint
To ensure that the material remains in good condition during the storage and transportation period, the sheet is coated with a passivation layer that protects the zinc from the effects of moisture. The problem is that this layer reduces the adhesion of the sheet to the extreme, so it must be removed before painting. To do this, phosphoric acid or even alcohol vinegar should be applied with a brush until the veneer darkens.
- ♦Remove rust
On older galvanized sheets, where the zinc coating has begun to break down, a natural oxidation phenomenon is likely to have occurred. This also significantly affects the application of paint, so it is necessary to eliminate all the damage that has been generated as a result of this oxidation. For this, it is advisable to use a fine-grained sandpaper.
In case the veneer has a hole generated by the blow of stone, or if you notice that it has been cracked by rust, it is possible to repair it using veneer putty. This product is very common in body shops and paint shops, where it is used for car body treatments, but it is also very useful and suitable for home use in the cases mentioned.
- ♦Deep cleaning
To continue, it is necessary to clean the surface manually, using light abrasive methods, such as a kitchen sponge, on the firmer side (usually green), removing any traces of grease, oils and dust. It is advisable to use a water-based detergent (also the kitchen one).
Once the cleaning process is complete, and after the smooth galvanized sheet has dried, an exterior latex primer coat specific for galvanized metals should be applied.
This base should be allowed to dry for the time indicated by the manufacturer in the product's instructions for use.
Now you only have to do the painting on the sheet. To do this, you can use different products. A good option is to paint with a metal natural smooth anti-rust enamel, which is a suitable decorating paint and provides long-lasting protection to iron and steel surfaces.
Another possibility is to use high-quality exterior latex paint. In this case, it is recommended to apply the product with a long-haired roller.
Tips when painting a galvanized sheet
- ♦Do not apply if the temperature is extremely low (less than 5 ° C).
- ♦Do not paint when there is ambient humidity higher than 85% or when rain is expected.
- ♦Do not paint under direct sunlight, as the evaporation of water impairs adherence.
Types of paint for galvanized sheet
The most important thing to obtain good results is to choose the correct colour. While some can be applied to different surfaces, others are not suitable for any use. Let's see what the paint options for sheet metal are:
Outstanding acrylics for sheet metal
They are acrylic-based products with high adhesion to apply on exterior galvanized sheet. They have excellent resistance to climatic agents and generous covering power, protecting for a longer time. They withstand temperatures up to 100ºC. These acrylics are the best choice in tin roof paint. You can get varieties of such paint for galvanized sheet
It has a base of acrylic polymers that gives it elasticity, resistance, adhesion and certain hydrophobic conditions. Covers completely dries fast, dilutes with water and washes off easily.
These stains stand out for their resistance to unfavorable weather conditions. They are very durable and can withstand high temperatures. Its downside is the cost of the paint.
Attention: It is not recommended to use any type of oil-based (alkyd) or synthetic type paints.