Custom Coater Finds Freedom in Zirconium Pretreatment

This is the story of how one general manager's commitment to research and environmental stewardship led Freedom Coatings to ditch iron phosphate for good and never look back.

For custom coaters, success often hinges on the ability to say yes—yes to new substrates, new industries and new challenges. But for one custom coater, saying yes to aluminum jobs was a source of anxiety rather than opportunity. Why? Because while its pretreatment chemistry was a hassle to clean out, causing a slowdown in production, it also wasn’t performing as it should. Freedom Coatings, a family-held business in Spartanburg, S.C., striving to live up to its name, decided a chemistry switch would give them freedom from challenging pretreatment tank cleanouts and unwanted, excessive coating thickness on aluminum.

Serving the aerospace, automotive, heavy equipment and architectural industries, the powder coating business offers an eco-friendly stripping system, high capacity ovens, two powder spray booths (12-ft. by 12-ft. by 30 ft.), clean air compression systems, heavy-duty material handling and custom packaging.

General Manager Samuel Cothran joined the business four years ago, making a unique switch from being an elementary school teacher to running a powder coating business. Moving abruptly from teaching to learning wasn’t easy, but he trained on the job. He researched everything he could about powder coating and relied on the knowledge and the advice of his suppliers. But one thing did not take Cothran much time to understand: the iron phosphate pretreatment system needed attention.

The Old Pretreatment Was “Tanking”

Freedom Coatings has a unique batch system that incorporates a recirculating hand wand for pretreatment. The closed-loop/zero-discharge system is highly efficient with water and chemical usage. Racks of parts are pretreated, rinsed, dried in an oven and then moved to the powder booth where they are painted, and then into the oven to cure.

A powder coating tech in full protective gear, including a respirator and spray suit, applies a vibrant blue coat to a metal rack inside a powder booth at Freedom Coatings. All photos are courtesy of Circle Prosco Inc.

The floor layout enables operators to efficiently move racks of parts from one station to the next. In-house fabrication capabilities give the shop the capacity to customize racks to handle a range of parts in all sizes and weights.

However, the company’s traditional iron phosphate pretreatment wasn’t producing quality results. In fact, the custom coater was experiencing adhesion issues on aluminum. Iron phosphate coatings are designed for steel, using an increase in pH that requires a reactive iron surface. While many iron phosphate products contain acid boosters to facilitate this reaction, traditional iron phosphate products are finicky when applied to aluminum substrates, which already have a weak native oxide layer.

Additionally, all phosphate-based pretreatments produce sludge and scale, which require maintenance. But cleanouts were a challenge at Freedom Coatings because the recirculating tank was difficult to access and required hazmat disposal.

Answering Customer Demands

Cothran knew his process was more reliable for steel substrate and strongly preferred those jobs. However, customers continued to send aluminum RFQs. So, he investigated alternative pretreatment solutions. His requirements were straightforward:

1. The new pretreatment must provide the same or advanced level of adhesion promotion and corrosion resistance across all substrates.

2. The new pretreatment must work in a single-stage recirculating tank.

3.  The new pretreatment must support Freedom Coatings’ commitment to environmental stewardship.

Cothran’s research kept turning up zirconium pretreatments, which work with, not against, aluminum’s native oxide layer. They use the same hydroxyl group to bond with aluminum, steel and galvanized substrate.

Also, zirconium oxide is self-limiting. Because it is formed through contact with active ions on the metal surface, the reaction automatically stops when those areas are covered. An iron phosphate, on the other hand, bonds with itself, enabling the deposition to continue to build thickness over time. In a manual, hand wand system, zirconium provides consistent results across all operators.

From a chemistry perspective, zirconium pretreatment is the clear winner. However, pretreatment is only one part of the challenge. With only one chemical stage and a recirculating system, the pretreatment solution must also provide adequate cleaning. To meet the demands of the Freedom Coatings’ existing equipment, Cothran needed a zirconium cleaner-coater.

Zirconium pretreatments also do not produce sludge or scale in the same way that phosphate products do. Switching to a heavy-metal-free and phosphate-free zirconium product would eliminate cleanouts and significantly reduce hazmat waste.

Samuel Cothran of Freedom Coatings is especially proud of Thomas and Vivan A. Wong Honor Tower at Unity Park in Greenville, S.C. The tower, which is constructed of concrete, steel and aluminum, was powder coated by Freedom Coatings. It pays homage to public servants including police, firefighters and other first responders.  

A Dynamic Duo

Through one of his powder suppliers, Cothran was introduced to Mike Pypiak at Circle-Prosco Inc. Together, they worked to maximize the flexibility and efficiency of the system while improving paint quality across all substrates. The challenges laid out by Cothran and Freedom Coatings were clear, and Pypiak confirmed a zirconium cleaner coater, Steelcote 1750 Cleaner Coater from Circle Prosco, as the best fit.

Over the next few weeks, Cothran and Pypiak identified a timetable to clean out and transition the chemistry from the old iron phosphate to the new zirconium product. After disposing of the existing iron phosphate solution, the entire system was thoroughly cleaned and rid of residual phosphate scale and sludge to create the best path forward for success with the new chemistry. After charging and optimizing the system with the new zirconium cleaner coater, the custom coater was off and running with its newly enhanced pretreatment process.

Once the system was operational, it was time to start processing parts. The first parts they ran were aluminum extrusions, and they looked great. What was once a substrate that gave Cothran and the shop anxiety now has become a source of confidence. The biggest drawback? Its local blast vendor’s new complaint was that it needed double or triple the amount of time to remove any powder applied by Freedom Coatings. The adhesion was greatly improved, which is a good problem to have. The shop experienced the same great performance across all substrates.

Over the next few months, Circle Prosco and Freedom Coatings monitored soil-load to ensure that the zirconium cleaner coater product was handling a robust and varied soil load. The recirculating hand wand equipment the coater chose was well suited to handle a zirconium cleaner coater because it had excellent filtration. The filtration system uses a multi-media approach, a high-efficiency water treatment process designed to remove suspended solids, iron sediment and turbidity. The robust filtration system paired with zirconium-based chemistry that does not form scale or sludge enables the shop to spend more time maximizing throughput than downtime for system maintenance and rework.

Now with the confidence of handling more jobs more efficiently, Freedom Coatings is evaluating future expansion, potentially with automation or with a larger system. Even with expansion, its current batch system will likely stay in place for large part profiles.

In the end, the chemistry switch enabled Freedom Coatings to paint its customers’ varied substrates, taking on projects it might otherwise have avoided. Adhesion issues are now in the rear-view mirror.

Pretreatment is a critical aspect of powder coating. When pretreatment chemistry does not pair well with the substrate that must be powder coated, it is time to make changes, as Freedom Coatings did. Now, coating aluminum no longer an adhesive issue for the custom coater with its new zirconium coater cleaner product in place.

For more information:

Freedom Coatings - www.freedomcoating.com

Circle Prosco Inc. – www.circleprosco.com