I'm sure on more than one occasion you've noticed that various elements look bad. This usually happens with those objects that are exposed to bad weather: parking doors, street lights, etc. It is common to find that they have chips in the paint and that it jumps easily. All these objects are made of galvanized steel. Let's see why this happens.
This surface has almost no pores, which makes it quite difficult for the paint to grip well. Therefore, when painting galvanized steel, we must apply specific products that provide good resistance, durability and adherence. Galvanized steel is a ferrous metal covered by a layer of zinc. If you try to paint galvanised steel with a paint that is not specific to this material, it is quite likely that it will be damaged. Although at first it may appear to paint well, over time, contractions in winter and expansions in summer, it is normal for it to crack and break.
From this moment on, you will begin to notice that the paint comes off easily. This is usually due to the lack of knowledge that we are dealing with galvanized steel.
Characteristics of galvanized steel
To be able to recognize which are the galvanized steel surfaces you must pay attention to the following characteristics:
- It is usually a fairly smooth surface. You'll find it's difficult to adhere to.
- It is pore-free, which prevents paint from penetrating the surface and makes a primer necessary.
- It is a very hard and resistant surface.
- It has a high resistance to oxidation.
- It is a very weather resistant surface. Therefore, it is a type of steel very used to make objects such as street lamps or benches.
- It has little resistance to acids.
How to paint a galvanized surface
Now that you know what a surface of Galvanized steel, what is the method I should use to paint it?
The first thing we have to do is prepare the surface we are going to paint. We'll degrease the surface well, using the Dirt Out degreaser. To do this, we take a cloth that is clean and dry. Wet the rag with the product and rub the whole surface until it is clean. It is best to do this a couple of times as the galvanizing, by its composition, always provides the feeling of being clean.
The second step is to apply a thin layer of grey Primer Fosder. This is a special primer that helps us provide good adhesion. As we have seen before, galvanizing is a too smooth surface, so it has a bad adherence. Therefore, it is essential to use a primer. We must allow it to dry between 20 and 30 minutes and, after that, we can paint with any type of finishing enamel.
As an important piece of advice, it is recommended that no more than 24 hours pass between the application of the grey Fosder Primer and the coat of topcoat we have chosen.