This stage is vital in allowing the paint finish to perform to its full potential. All paints are porous and will over time allow atmospheric conditions to permeate through the coating onto the metal. To safeguard against this, all substrates are chemically pre-treated in order to protect against corrosion and promote good adhesion.
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The pre-treatment at C & O Powder Coatings is a classic seven stage immersion system where work is loaded into cages before being dipped through seven tanks.
1. DE- GREASE
All metal substrates must be clean prior to any other stage. All grease or lubricant residue from the manufacturing process is removed.
2. WATER RINSE
Between each chemical rinse, a water rinse is necessary to clean the work from any chemical residue.
3. ACID ETCH (Aluminium only)
The surface of the Aluminium is de-oxidised and any contaminants on the surface of the alloy are removed. Etching of the aluminium is vital in preparing the substrate for the oxsilan stage.
4. WATER RINSE
As per stage two
5. DEMINERALISED WATER RINSE
Before entering the tank, the water is passed through a plant that removes all heavy metals and minerals. The water is kept at a conductivity of less than 200 microsiemens. This stage is vital in ensuring the ongoing integrity of the Oxsilan stage.
The substrate is coated by a Silane & Zirconium based polymer. This bonds to the substrate providing the metal with excellent corrosion protection whilst promoting good adhesion.
7. DEMINERALISED WATER RINSE
The water is kept at a conductivity of less than 30 microsiemens. Rinsing the metal completely clean ensures that in the drying stage no contaminants will deposit onto the surface of the metal. Surface impurities could affect the adhesion and the performance of the cured paint finish, Regardless of how good the stages prior to this are, unless the de mineralised rinse is well maintained, the paint will not perform to its full potential.
8. DRYING OVEN
Hot air is circulated around the work to dry the metal off.
After pre-treatment the metal is suspended on a conveyorised production line and passes into the spray booth for coating. The powder which is held in a fluidised hopper bed is carried to the spray gun using compressed air. As the powder passes out of the gun, the particles are charged and therefore attracted to the earthed piece of metal. This creates an even coating as it wraps around the work piece.
After coating, the production line moves the work into the tunnel oven where it is baked. Once the curing is complete the substrate is inspected for defects, paint thickness, colour and gloss level. Provided there are no issues, the product is packed and made ready for despatch.
C & O is proud to have been involved in many prestigious projects over the years. Some of our most recent sites include: