When it comes to quality industrial coatings that last, the work begins well before the powder spray booth. While the coating application and curing processes are certainly critical, there’s no getting around the fact that exceptional quality is fundamentally built on an exceptional pretreatment process.
That’s especially true for coating lines that process multiple materials — typically steel and aluminum. In fact, many aluminum coating failures originate in pretreatment systems designed to process different substrates.
At Winona Powder Coating, our process integrates an aluminum-only pretreatment line to avoid the common issues that our competitors face. For one, we eliminate the risk of chemical cross-contamination and the quality issues that come with it. Our pretreatment process is also specifically optimized for the surface chemistry of aluminum parts, ensuring maximum powder adhesion and lasting durability
Originally developed for the automotive industry with the adoption of aluminum body panels, and predominately utilized in “captive” coating lines, this technology is now available to you through Winona Powder Coating.
Solving Aluminum Coating Failures with an Aluminum-Only Pretreatment Process
Aluminum is increasingly specified across industries for its strength-to-weight advantages, corrosion resistance, and performance benefits. However, many aluminum powder coating quality issues are not caused by the coating itself, but by pretreatment systems that were never designed specifically for aluminum.
In other words, for many common issues like generally poor adhesion, corrosion creep, and inconsistent finishes, the source may be the pretreatment process itself.
Winona is one of the Midwest’s premier powder coaters with an aluminum-only line to address these challenges. Moreover, our company is an AAMA certified applicator for multiple major powder producers. Pretreatment isn’t just preliminary, but integral to our process; and quality is without compromise.
By eliminating the compromises inherent in bi-metal pretreatment systems, Winona delivers more consistent, reliable, and durable finishes for your powder coated aluminum components.
Why Aluminum’s Natural Oxide Layer Creates Quality Risks
Aluminum is classified as a light metal with a density of just 2.7 g/cm³, compared to 7.9 g/cm³ for steel. While aluminum naturally forms a thin oxide (passive) layer that provides limited corrosion protection in clean, dry conditions, this layer is inconsistent and chemically unstable in many real-world environments.
The passive layer can be attacked by chlorides or dissolved by acidic and alkaline media, accelerating corrosion beneath coatings. Its undefined nature also leads to variability that negatively impacts coating adhesion, corrosion resistance, welding consistency, and adhesive bonding performance.
Why Bi-Metal Pretreatment Lines Compromise Aluminum Performance
Conventional bi-metal coating lines are designed to process both steel and aluminum using shared pretreatment chemistry. This requires chemistry settings to be balanced rather than optimized, often resulting in insufficient surface preparation for aluminum.
These compromises increase the risk of adhesion failures, corrosion creep, cosmetic variation, and inconsistent results across production runs — particularly for demanding applications.
Improving Aluminum Coating Quality with No Bottlenecks for High-Volume Runs
Winona’s aluminum-only powder coating line features a state-of-the-art Henkel pretreatment conversion coating combined with a chromium-free etch passivation system developed specifically for aluminum substrates. This process stabilizes electrical surface resistance while improving powder coating adhesion, adhesive bonding performance, and long-term corrosion resistance.
Beyond better quality, our dedicated line essentially eliminates the bottleneck on the number of aluminum parts we can coat. While our competitors are typically limited in aluminum coating capacity, we can tackle your high-volume aluminum runs without compromise.
Winona’s Aluminum-Only Pretreatment Line:
Our unique pretreatment line incorporates dedicated washer stages engineered exclusively for aluminum.
- Stage 1 Washer: A silicate-free, low-alkaline liquid cleaner optimized for aluminum and specialty alloys, removing contaminants without over-etching.
- Stage 3 Washer: A chromium-free etch passivation treatment formulated specifically for aluminum parts, ensuring uniform surface activation and reliable coating performance.
- Stage 5 BONDERITE M-PT 54 NC: Henkel’s chemically-advanced BONDERITE M-PT 54 NC for post-passivation is sprayed during the final rinse to eliminate underfilm corrosion and maximize powder adhesion.
Because the chemistry is tuned solely for aluminum, parts receive consistent surface preparation from run to run — something bi-metal systems struggle to achieve.
Long-Term Corrosion Performance Depends on Pretreatment Control
Winona’s pretreatment process protects aluminum parts prior to coating and helps prevent post-coating creepback corrosion. This is especially critical for welded assemblies, adhesive-bonded components, and parts stored for extended periods before coating.
The result is reliable long-term performance in demanding service environments.
Why OEMs Require Aluminum-Specific Pretreatment Chemistry
The pretreatment chemistry used on Winona’s aluminum-only powder coating line is approved by leading global OEMs, including Volkswagen, Daimler, BMW, Jaguar Land Rover, and Volvo. These approvals and our list of certifications validate the process as a proven solution for high-performance, corrosion-resistant aluminum coatings.
Quality Is Engineered into Our Process from Start to Finish
By engineering a pretreatment process exclusively for aluminum, Winona addresses the root causes of common aluminum powder coating failures. The result is stronger adhesion, improved corrosion resistance, and consistent, high-quality finishes that outperform conventional bi-metal coating lines.
- Optimized chemistry and temperatures for aluminum processing
- Faster processing with no line changeover delays
- Superior aluminum-specific conversion coating performance
- Consistent, predictable processing regardless of batch size
- Higher throughput and reduced lead times
Our dedicated line represents a significant capital and operational commitment that most competing powder coaters simply don’t invest in. That directly translates into superior aluminum coating quality and faster delivery for our customers. See the advantage for yourself by partnering with Winona for your next aluminum powder coating project.
