When a surface is to be painted, the focus is usually on the painting process and the products involved. However, one of the most important things in any painting process is preparing the surface.
FACTORS TO CONSIDER WHEN PREPARING THE SURFACE
There are a number of factors to consider when preparing surfaces. One must consider whether the material is metal, plastic or another.
ASPECTS TO CONSIDER:
- Nature of the material to be painted
- Previous surface condition
Existence of rust (oxidation) or previous coats of paint
- Geometry and size of the surface
- Cost
Whether the material is painted or not. Whether it has rust or any defects.
You also have to consider the geometry, the size and of course the cost.
Now let us look at the different types of metal surface preparation.
DEGREASING:
Solvent-based or water-based products can be used. The most common method is to use a dry cloth and a damp cloth.
But there are also other types such as pressure gun or immersion 5"
MANUAL OR MECHANICAL CLEANING:
This involves preparing the surface to remove rust, mill scale or other impurities that may be present.
SHOT BLASTING:
Shot blasting consists of projecting a material, that can be metallic or non-metallic, onto the surface to be cleaned at high speed and with compressed air.
Depending on the speed, size, type or material used in the shot blasting, a different level of cleanliness or roughness will be obtained. The specification will indicate the level of cleanliness and roughness required.
THE SPECIFICATION WILL DETERMINE THE LEVEL OF CLEANLINESS OR ROUGHNESS TO BE REQUIRED
It must also be considered that some types of paint require having a certain roughness profile to maintain adhesion. This is the case with zinc-rich epoxies, thermally sprayed zinc, etc.
It is the most effective system for surface cleaning and preparation but it must be considered that after blasting, steel is highly exposed to oxidation and must be covered immediately afterwards.
27 авг 2024
