Exceeding Modern Quality Control Standards for Today’s Powder Coating Projects

Powder coating has risen in popularity across a huge number of industries and product applications largely due to the efficiency of the process and the consistent quality it provides. From specialized industrial and agricultural equipment to high-volume automotive parts, metal stampings and more, powder coating provides today’s manufacturers with a reliable, cost-effective way to give their products a premium, long-lasting surface finish.

Because of powder coating’s reputation for superior results, customers’ quality expectations tend to be higher than ever. Even small flaws in the finish or uneven thickness will not be tolerated for many products in the marketplace. That’s why it’s important to choose a powder coating company that employs a robust quality control and product inspection process – it helps ensure you get the results that you expect.

Superior Quality Control – It’s the Winona Way

At Winona Powder Coating, our motto is quality from start to finish. That’s much more than a mere tagline for our company. With more than 50 years of experience under our belts, we’ve established a system of absolute quality assurance that extends from the onboarding process all the way through to product delivery. We are an ISO 9001-2015 certified coater committed to superior quality and consistency for every product.


An Overview of Our Quality Control and Inspection Processes:

  • Pretreatment monitoring
  • Oven Cure verification
  • Thickness testing
  • Gloss evaluation
  • Color verification
  • Cure confirmation
  • Adhesion testing
  • Mandrel bend testing
  • Visual inspection to customer specification
  • Impact testing
  • Salt spray test
  • Weathering test
  • Cyclical corrosion test

Ensuring Quality from the Start

Before your project even begins, we make sure maximum quality can be reached from the start. Winona’s coating experts collaborate closely with customers to choose the best finishing method and specific powders, as well as to pinpoint any design concerns and establish a baseline expectation for the product end quality based on customer specifications.

Pretreatment Monitoring

Once your project is underway, the first step is pretreatment. Proper pretreatment ensures full and even adhesion to the substrate – which means an even coat on every part. Surface pretreatment also helps ensure the coating's long term adhesion to provide lasting corrosion resistance. Our process begins with detailed surface cleaning to remove all dirt, oils, oxides, and other contaminants from the workpieces.

Cleaning and Chemical Conversion

The cleaning procedure involves purified water along with a specialized chemical conversion process of the surface. A agent neutralizer stabilizes the conversion coating, while the temperature of the rinse increases the solubility of the residues and improves dry off time. Proper flow patterns and rinse volume promote a more thorough rinse. Overflows and screens are used for the removal of the soils, oils, and other contaminants, leaving the surface completely clean and ready for powder coating.

Finally, Winona employs a detailed oven cure verification process. This ensures all curing ovens operate at full efficiency and provide proper curing for every part.

Coating Thickness Testing

Just like it sounds, thickness testing ensures the coating thickness is up to standards and even across the entire part surface. Thickness levels vary by project, but we generally test for a range between 0.002” and 0.004” (2 to 4 thousandths of an inch). A coating of 0.002” to 0.004” usually gives you complete coverage and a long-lasting coat.

Evaluating the Gloss and Aesthetic Qualities

We inspect and confirm the aesthetic qualities of your coated parts, including the glossiness. We ensure every coated part is free from gaps in coverage or visual defects. We are constantly actively looking for defects to ensure maximum consistency and so that any issues can be fixed before delivery. 

Cure Confirmation

Proper curing requires the correct temperature and dwell time that allows the powder coat to reach its formulated hardness and chemical resistance properties. When testing the cure, we make sure that there aren’t any overbake areas, where the powder has cured in a dry and brittle fashion, or underbake, where the powder has not completely cured.

Adhesion Testing

Adhesion testing measures how well the powder paint sticks to the part once it is fully cured. As with the cure test, the adhesion test results can be altered by either over- or underbaking.

We employ a specialized test table to perform the adhesion testing once the part has been coated and cured. Using a utility knife, we scribe a section of the part’s coating with a grid-like appearance, cutting all the way to the bare metal to fully test the coating adhesion.

Visual Inspection per Customer Standard

The second part of your appearance testing routine involves our team taking time to communicate with our customers. Every customer should have an idea of what they consider to be an acceptable finish, but it may take some discussion to determine what’s realistic and measurable. A finish standard can be as simple as no more than two visible surface imperfections per square foot. Gloss and color standards may also be included. If a customer has exact requirements, we make certain the customer receives exactly what they expect.


Our Quality Certifications:

  • ISO-9001-2015 Quality Management Certified, NQA Registrar, Upgraded Certification Scope to Include E-Coat, 2021 Recertification April 2022​
  • UL Certified Coating Supplier for Electrical Components​
  • John Deere, Preferred Supplier, Approved for the Following:​
  • JDM F17X2  Powder Substrate Approvals Include Cast Iron, Aluminum, Cold Rolled Steel​
  • Colors Include John Deere Green ( F9 ), AG Yellow, Low Gloss Black. Medium Gloss Black 
  • E-Coat Substrate to Include Cast Aluminum, Hot Rolled Steel, Cold Rolled Steel and Cast Iron
  • Hot-Rolled Steel as a Substrate for Powder
  • Hendrickson Approvals for E-Coat/Top Coat to 750068-007 and  008, 2021.
  • AAMA 2603/2604/2605 Approved Applicator of Architectural Powder Coatings, Akzo Nobel, 2021
  • AAMA 2603/2604/2605 Approved Applicator of Architectural Powder Coatings, Axalta, 2021
  • AAMA 2603/2604/2605 Approved Applicator of Architectural Powder Coatings, IFS, 2021

Quality American Powder Coating Services Since 1974

For more than half a century Winona Powder Coating has stood as one of the Midwest’s premier powder coating service providers due to the quality and consistency of our services. With two locations based out of Etna Green and Elkhart, Indiana, our company has served the agricultural, automotive, and industrial powder coating sectors along with many other quality-focused industries.

Winona Powder Coating

The Power of Powder: Advantages and Applications of Industrial Powder Coating Services

Powder coating is generally the most efficient and cost-effective way to give industrial parts a...
Read more
Winona Powder Coating

Rust Never Sleeps: The Anti-Corrosion Advantages of Powder Coating and E-Coating

Read more