Liquid paints & powder coating

Process duplex Powder coating Lacquering Metallization Service activity

Protect & beautify

The combination of a paint system on hot-dip galvanized steel forms what is known as a duplex system.

The hot-dip galvanizing layer, consisting of three layers of iron-zinc alloy and one layer of pure zinc, offers excellent protection against steel corrosion.

A paint system (liquid or powder) also protects steel against corrosion, so using both systems together offers prolonged protection.

Before applying a powder or liquid paint system to hot-dip galvanizing, the zinc layer must be made suitable for coating. This involves mechanical or chemical pre-treatment of the zinc surface to eliminate overspray, drips and any imperfections that may interfere with the paint system. Several levels of finish can be determined according to our customers’ specifications.

The Duplex system is standardized in several standards, depending on the type of paint (Powder coating or Lacquering)

EN ISO 15773 / 2009: Industrial application of organic powder coatings to hot-dip galvanized or sherardized steel products – Specifications; recommendations and guidelines.

EN ISO 13438 / 2013 : Paint and varnish – Organic powder coating for hot-dip galvanized or sherardized steel products used in construction.

THE DUPLEX STAGES

Powder paint application

Powder coating is easy to apply and environmentally friendly, for uniform, long-lasting finishes on metal substrates.

Powder coating is a painting process that begins with the application of powder paint (epoxy, polyester, mixed epoxy-polyester) by electrostatic spraying. This is then polymerized in a baking oven at 200°C to form a paint film.

Advantages :

Multiplicity of looks and colors.
Excellent resistance to corrosion, chemical attack and fire.
Solvent-free paint.
Excellent resistance to elasticity, impact and wear.
Can be applied to all metallic materials

Powder coating is standardized according to several standards:

NF EN ISO 2813 – November 2014: Paints and varnishes – Determination of gloss index at 20 °, 60 ° and 85 °.

NF EN ISO 2360 – October 2017 : Non-conductive coatings on non-magnetic electrically conductive base materials – Measurement of coating thickness – Amplitude-sensitive eddy current method

NF EN ISO 2409 – April 2013 : Paints and varnishes – Grid test

NF EN ISO 3231 – April 1998 : Paints and varnishes – Determination of resistance to moist atmospheres containing sulfur dioxide

NF EN ISO 2810 – December 2004 : Paints and varnishes – Natural aging of coatings – Exposure and evaluation

NF EN ISO 9227 – June 2017 : Corrosion testing in artificial atmospheres – Salt spray testing

THE POWDER COATING PROCESS

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Liquid paint or lacquer

This process allows the use of specific paints according to customer specifications.

Liquid paint is applied to various surfaces using a pneumatic spray gun, after shot-blasting or degreasing.

This process is most often used in industry. Allows the use of specific paints according to customer specifications (decontaminable paint, marine paint, etc.).

Liquid paint can also be used for parts that cannot withstand the heat of the powder-coating oven (PVC, lead, etc.), or for larger structures that cannot fit into the powder-coating booth and oven.

Lacquering is standardized according to several standards :

NF EN ISO 12944-1 – December 2017 : Paints and varnishes – Anticorrosion of steel structures by paint systems.

NF T34-550 / 554 : Peints et vernis – Systèmes de peinture pour la protection des ouvrages métalliques – Spécifications.

THE LACQUERING PROCESS

Preparation & protection

Shot blasting, more commonly known as sand blasting, consists of continuously projecting small steel balls onto the surface of the parts to be treated, at high speed.

Shot-blasting prepares the surface to be painted by removing rust, scale, machining burrs and grease…. and creates the roughness required for better adhesion of the future liquid paint or powder coating.

This operation is defined by the ISO 8504/2/2000 standard, which classifies the treated substrate into 3 quality levels: Dsa 2; Dsa 2.5 and Dsa 3, depending on the type of paint coating subsequently applied and the guarantees formulated.

Zinc spray metallization involves melting the metal in wire form and spraying it with a flame gun (shoopage).

Thanks to its electrochemical properties, zinc blocks the oxidation process of the steel with which it comes into contact.

Advantages :

Longer service life.
Efficient protection against corrosion, and longer maintenance intervals.
Can be used on all types of metal structures, especially those subject to particularly aggressive environments.
Seals wounds in the event of impact or injury to the coating, with no risk of corrosion progression.
Excellent support for paint coatings.

Metallization is standardized in accordance with:

NF EN ISO 2063-2 – October 2017 : Thermal spraying – Zinc, aluminium and alloys of these metals – Part 2: execution of corrosion protection systems – Thermal spraying – Metallic and inorganic coatings – Zinc, aluminium and alloys of these metals.