Metal painting and anti-corrosion protection

Nowadays, what matters most is the high quality of finished products. When it comes to steel parts, it is worth going to an industrial paint shop that will take care not only of the aesthetics, but also the resistance and anti-corrosion protection of such elements. We can protect steel and other metals against corrosion by galvanizing, as well as powder and liquid painting. What is the best anti-corrosion method? Let’s find out!

Anti-corrosion protection – methods

When producing metal parts, especially from carbon steel, it is always necessary to apply an anti-corrosion coating. The most frequently used solutions, which are used primarily in construction, automotive, household appliances and in the broadly understood industry, are:

  • wet painting,
  • hot-dip galvanizing,
  • powder painting.

When choosing a safe method, you need to answer a number of questions:

  • is the applied coating intended only for protection against corrosion or also for decorative purposes?
  • what is the intended appearance of the painted surfaces?
  • is the coating thickness important in terms of dimensional tolerance?
  • what budget do you have?
  • what additional resistances are required?

Wet painting is the cheapest and most decorative, but provides the least level of protection. The next recommended method is powder coating, and the last (most durable) method is hot-dip galvanizing.

Spray painting, powder coating and hot-dip galvanizing – differences

Below we have prepared a summary of the most important differences between the three methods of anti-corrosion protection of steel.

Wet painting:

  • Durability: Long-term durability, depending on the number of layers and their thickness as well as the selected visual effect.
  • Price: The cheapest method of protection against corrosion.
  • Aesthetics of workmanship: High aesthetics of workmanship, freedom to choose colors, gloss, tactile effects and non-standard solutions.
  • Susceptibility to damage and abrasion: greater sensitivity to scratches than for other methods, but this coating still provides quite good protection.
  • Ease of coating repairs: Simplicity of reconstructing the anti-corrosion coating.
  • Possibility of use in aggressive chemical environments: Need to adapt solutions to requirements.
  • Preparation of the steel structure: Sandblasting to a cleanliness level of SA2.5.

Galvanizing:

  • Durability: Extremely long service life.
  • Price: The method is about 30% more expensive compared to wet painting.
  • Aesthetics of workmanship: The phenomenon of yellowing and the so-called white rust. No color customization options.
  • Susceptibility to damage and abrasion: Less susceptible to damage than when painting.
  • Ease of coating repairs: Complicated reconstruction of the anti-corrosion coating.
  • Possibility of use in aggressive chemical environments: Duplex system recommended.
  • Preparation of the steel structure: Making technological holes to allow free flow of zinc.

Powder painting:

  • Durability: Extremely long service life.
  • Price: The method is approximately 150% more expensive than wet painting.
  • Aesthetics of workmanship: High aesthetics of workmanship, freedom to choose colors and structures, but many effects are unavailable (e.g. soft-touch).
  • Susceptibility to damage and abrasion: Comparable resistance to galvanizing.
  • Ease of coating repairs: Complicated reconstruction of the anti-corrosion coating.
  • Possibility of use in aggressive chemical environments: Need to adapt solutions to requirements.
  • Preparation of the steel structure: Sandblasting to a cleanliness level of SA2.5.

Why is it worth protecting steel with galvanizing?

There are many reasons why you should choose hot-dip galvanizing. It is primarily a durable method of securing steel structures. The galvanizing process itself requires several material processing steps: degreasing, etching, rinsing, fluxing, galvanizing and cooling of the protected steel elements.

Powder and wet coating – is this a beneficial method of anti-corrosion protection?

Painting is an advantageous and, above all, the cheapest method of anti-corrosion protection of steel structures. Unfortunately, in the case of wet painting, we must take into account that the steel surface will not be as well protected as in the case of powder coating or hot-dip galvanizing.

In this case, to carry out the painting process and maintain the durability of the coating, we must clean the steel by sandblasting, degreasing and smoothing. Additionally, it is necessary to use appropriate paint in accordance with the PN-EN ISO 12944-5 standard, i.e. acrylic, alkyd, epoxy, PVC or other.

The undeniable advantage of liquid painting is the unlimited choice of the appearance of the coating – first, an anti-corrosion primer is applied, followed by any varnish, including unusual ones, such as soft-touch, rubber, pearl, chameleon, all colors, metallics, glosses and many others.

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