Surface Treatment Prior to Coating


To achieve the quality of surface treatment required by the client and also comply with the standards or seals of surface finishes on the market. it is essential that the surfaces to be coated first receive a specific pre-treatment, depending on the type of material (steel, aluminum, galvanized, plastic, etc)

The functions of this type of surface treatment are multiple:

  • Clean the parts from external contamination (environmental dust, machining oils, storage corrosion, etc.)
  • Prepare the surface to be coated / Molecular Activation.
  • Improve or promote adhesion for future coating.
  • Increase resistance to corrosion and longevity of parts.
  • Comply with the construction standards of each sector and each piece to be painted.

For metal parts, the surface treatment consists of several stages (normally 3, 5 or 8 stages) and is carried out in a continuous line through a spray tunnel, or step by step, thanks to a bridge-crane system and immersion baths. The most common process steps proposed by chemical suppliers are as follows:

  • Acid or alkaline attack / degreasing.
  • Microcrystalline phosphating: iron phosphating, zinc phosphating.
  • Chrome plated
  • Chromium free conversion
  • Titanium / zirconium treatment
  • Nanoceramic coating
  • Anodizing process
  • Dry ice blasting (or dry ice)

In the case of plastic parts, the pretreatment stages depend a lot on the volume of parts to be produced and the quality required by the industry that produces them. For small volumes, the treatments are normally manual with cloth and solvent, while for the automotive industry automatic processes are developed continuously with robots (for example, bumpers, rear-view mirrors, central dashboard, etc). The most common technologies used are the following:

  • Sanding and solvent cleaning
  • Dry ice blasting (or dry ice)
  • Activation by flaming
  • Cleaning and activation with atmospheric plasma or vacuum
  • Surface deionized

According to the needs of each client, Shinjiru is able to develop a wide variety of pretreatment and surface treatment lines, together with process water production systems (demineralized, ionized, filtration and heating …) as well as drying ovens.

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