Chrome Free or Phosphate Pre-Treatment Options

The application of a powder film provides two main criteria: It protects the substrate onto which it is applied and it makes your product look better.

With this in mind it is crucial that the correct pre-treatment and powder technology is chosen. When you are putting your name to a brand or product it is critical that sub suppliers in the manufacturing process can sustain your needs through quality, service and technical support and an understanding of what you are trying to achieve.

In this ever demanding economy it is clear that we must strive to offer solutions that take account of cost, resource depletion, longevity and health and safety.

The foundation to any good quality coating is the pre-treatment. This is because powder, as a cured film, is actually permeable. The solid cured film contains many millions of micro pores which allows moisture to permeate through the film which can potentially bring on the onset of corrosion of the substrate from beneath the powder coatings.

To ensure longevity of the coating it is thus incredibly important to ensure that the correct pre-treatment has been selected.

Euro Quality Coatings offer 2 methods of chemical pre-treatment. Both are applied via a 56 metre long 11 stage pre-treatment system which applies the pre-treatment via a series of high pressure sprays.  In this manner the chemical or rinse water impinges itself onto the surface of the substrate. The benefit of this system is the lack of operator intervention from the time of initial loading onto the overhead conveyor, to the time the part is fully processed and inspected at the process completion. This eliminates any risk of damage whilst basket loading but, more importantly, negates any risk of contamination to the part from operator handling.

Chrome Free Pre-treatment

In early 2019 Euro Quality Coatings removed Chromate Pre-treatment from the business in favour of the equally robust and more environmentally friendly Henkel Bonderite Chrome Free Pre-treatment.

The chrome free system adopted by EQC conforms fully with the requirements of BS EN 12206-1:2021 and is fully audited by our chemical process technicians throughout the production day. The technicians perform merely a backup monitoring of the process, as it is auto dosed.

Furthermore, our pre-treatment supplier has full access to the plant operating performance via the internet portal and conducts a weekly audit of the plant to ensure all working parameters are being met.

The Aluminium is initially processed via an alkaline etch cleaner which removes surface contamination and microscopically etches the surface of the substrate in preparation for the chrome-free conversion layer. After alkaline etch and cleaning, the part is subject to pressurised towns’ water rinse to ensure all contaminants are removed before entering the chrome-free zone. Following chrome-free conversion coating a final demineralised water rinse is sprayed onto the part. This last DI rinse ensures that the part is completely free of water contaminants prior to force drying through a gas fired convection oven.

The chrome free process provides an excellent base for the bonding of powder on aluminium to ensure an excellent finish and corrosion free surface.

Lastly, the chrome free process is kinder to the environment and a more sustainable solution as the process uses less energy than conventional coatings.

We operate our own internal salt spray tests.

Phosphate Pre-treatment

Where the substrate is of a ferrous base we adopt a Zirconium Phosphate pre-treatment route. This again provides a chemically bonded pre-treatment layer which protects the substrate from future corrosion attack under the powder coated film.

The ferrous substrate is initially processed via an alkaline cleaner which removes surface contamination and oils from the surface of the substrate in preparation for the phosphate conversion layer. After alkaline cleaning the part is subject to two pressurised towns’ water rinses before entering the phosphate zone. Following phosphate conversion a further two towns water rinses are sprayed onto the part prior to a final rinse in demineralised water.

We hope the above narrative gives some degree of useful information. Should you require any further technical assistance regarding your powder coating requirements then please feel free to get in contact with us.

See also Powder Coating Colours