General Information on Electrostatic Powder Coating

Electrostatic Powder Coating Production Stages

🧪 1. Raw Material Preparation

Resins, pigments, fillers, and additives are carefully weighed. Each material is specially selected to ensure the durability and color quality of the powder coating.

Main raw materials used in powder coating production:

• Resins (Epoxy, Polyester, Epoxy-Polyester hybrid, etc.)

• Pigments (provide color and opacity)

• Fillers (enhance mechanical strength and surface properties)

• Additives (used for adjusting flow, gloss, matte finish, etc.)

All raw materials are precisely measured and prepared. This stage is crucial for quality control since it directly affects the coating's performance.

⚙️ 2. Mixing (Premix)

All raw materials are blended in high-speed mixers to achieve a homogeneous mixture. This stage ensures perfect color distribution in the following processes.

The weighed materials are mixed in high-speed premixers until a uniform blend is achieved.
Purpose: To evenly distribute each component and prepare the mixture for the extrusion stage.

🔥 3. Extrusion (Melting and Blending)

The prepared mixture is melted and fused in special machines at controlled temperatures. At this stage, the material begins to take the form of powder paint.

The homogeneous mix is melted and mixed in a special machine called an extruder at a specific temperature.
During this process:

• The resin melts, and pigments and additives dissolve within the resin.

• A homogeneous molten coating mix (melt) is formed.

• The material exiting the extruder usually appears as a thin sheet.

❄️ 4. Cooling and Crushing

The hot material is cooled and solidified, then broken into small chips. This step prepares the material for the grinding stage.

The material coming from the extruder is:

• Cooled on a cooling belt,

• Crushed into smaller pieces using a crusher.

At this stage, the coating is solid but still processable.

🌪️ 5. Grinding (Micronization)

The crushed pieces are finely ground in special mills to achieve a powder with micron-sized particles. The particle size of the coating typically ranges between 30–50 microns.

The cooled and crushed material is micronized in special grinding mills until it becomes a fine powder.
The average particle size is around 30–50 microns.
During grinding, particle size distribution determines the final product's quality.

🧹 6. Sieving and Classification

The powder is passed through special sieves to separate coarse particles. Only powders with the ideal particle size are sent for packaging.

The ground powder passes through sieve systems where oversized particles are removed.
Only powders with the desired particle size are directed to the packaging stage.
Some manufacturers also use air classifiers during this step for precise size separation.

📦 7. Packaging

Moisture-sensitive powders are filled into special bags in a controlled environment. Each product is labeled for traceability and prepared for shipment.

Powder coatings with the proper humidity level and particle size are:

• Filled into bags or boxes using automatic systems,

• Labeled and assigned a lot number for full traceability.

During packaging, ambient temperature and humidity are kept low because powder coatings are sensitive to moisture.

✅ 8. Quality Control

Each production batch undergoes tests for color, flow, gloss, and durability. Only the coatings that pass all tests are delivered to customers.

The final product is tested according to criteria such as:

• Color consistency

• Surface appearance (gloss or matte finish)

• Mechanical strength

• Flow properties

• Application performance (electrostatic charging, curing, etc.)

🌿 Powder Coatings: Environmentally Friendly and Sustainable Solutions

Powder coatings cause significantly less environmental impact compared to traditional liquid paints. Since they contain no solvents (volatile organic compounds – VOCs), they do not release harmful gases into the air.

♻️ Environmentally Friendly Features
Solvent-free:
Powder coatings do not contain solvents or chemical thinners, preventing the emission of harmful gases (VOCs) into the atmosphere.

Low waste rate:
Excess powder during application can be collected and reused, achieving up to 95% material efficiency.

Energy-saving:
Production and curing processes are optimized to minimize unnecessary energy consumption.

No water pollution:
Unlike liquid paints, there is no washing or wastewater generation.

🌍 Sustainability Advantages
Long-lasting coating:
Powder coatings offer high resistance to impacts, UV exposure, and chemicals, extending product lifespan and reducing resource waste.

Recyclable:
Metal products coated with powder paint can be recycled without harming the environmental cycle.

Safe for workers:
No harmful solvent fumes are generated, providing a healthier working environment.

💡 In conclusion:
Powder coatings are a strong representation of environmentally conscious manufacturing. They protect nature while offering durable, efficient, and sustainable solutions in industrial production.

⚙️ Powder Coating Application Equipment

Powder coating systems are generally divided into three main groups:
1️⃣ Application (coating) equipment
2️⃣ Curing (oven) equipment
3️⃣ Support (auxiliary) equipment

🎯 1. Application Equipment
Ensures the powder adheres evenly and uniformly to the surface.

Electrostatic Powder Coating Gun:
Imparts an electrostatic charge to the paint particles, allowing them to stick to the metal surface. (Can be manual or automatic)

Powder Coating Control Unit:
Controls the gun's settings such as voltage, air pressure, and powder flow.

Powder Feeding Unit / Hopper:
Ensures a continuous and balanced flow of powder to the gun.

Air Compressor:
Provides the necessary compressed air for the gun to operate.

🔥 2. Curing (Oven) Equipment
After application, the powder is baked to fully adhere to the surface.

Curing Oven:
Coated parts are baked at a specific temperature (usually 160–200°C) for 10–20 minutes.
Oven types:

• Gas or electric ovens

• Tunnel or booth type

Conveyor System:
Automatically transports parts from the coating booth to the curing oven.

🧭 3. Support Equipment
Ensures the coating process is clean, efficient, and environmentally friendly.

Powder Coating Booth:
The area where coating is applied, preventing powder from dispersing into the environment.
(Can be equipped with steel or plastic filters)

Filtration and Recovery Unit:
Collects overspray powder inside the booth, filters it, and makes it reusable.

Surface Cleaning and Phosphating Unit:
Removes oil, rust, and dirt from the metal surface before coating, improving powder adhesion.

💡 Summary:
Powder coating systems consist of the following essential equipment:
➡️ Powder coating gun
➡️ Control unit and feeding hopper
➡️ Powder coating booth and filtration system
➡️ Curing oven
➡️ Conveyor system
➡️ Surface preparation equipment

🎨 Types of Powder Coatings

Electrostatic powder coatings are produced in different types based on their applications and properties.
Each type provides specific durability, appearance, and performance for different needs.

💎 1. Epoxy Powder Coatings
🧩 Applications: Interior spaces (office furniture, electrical panels, metal cabinets)
✅ Advantages:

• Excellent chemical resistance

• Smooth and glossy finish

🌿 2. Polyester Powder Coatings
🏗️ Applications: Exterior surfaces (aluminum frames, metal facades, exterior doors)
✅ Advantages:

• Resistant to UV and weather conditions

• Maintains color and gloss for a long time

• Aesthetic and ideal solution for outdoor use

⚙️ 3. Epoxy-Polyester (Hybrid) Powder Coatings
🏠 Applications: Interior products (appliances, shelving systems, metal furniture)
✅ Advantages:

• Combines epoxy's chemical resistance with polyester's flexibility

• Cost-effective and versatile

• Frequently preferred for industrial production

✨ 4. Polyurethane Powder Coatings
🚗 Applications: Both interior and exterior (automotive parts, decorative metal surfaces)
✅ Advantages:

• Superior gloss and scratch resistance

• High protection against UV and chemicals

• Long-lasting aesthetic appearance

🧱 5. Thermoplastic Powder Coatings
🔩 Applications: Surfaces requiring protective coating (wire baskets, pipes, equipment)
✅ Advantages:

• Thick and flexible coating

• Excellent resistance to corrosion and impact

• Preferred for industrial protection applications

💡 Summary Table:

Type Application Advantage
💎 Epoxy Interior Chemical resistance, glossy finish
🌿 Polyester Exterior UV and weather resistance
⚙️ Epoxy-Polyester Interior Cost-effective, balanced performance
✨ Polyurethane Interior & Exterior Gloss, hardness, long lifespan
🧱 Thermoplastic Industrial Thick coating, high protection 

🧪 Powder Coating Tests

Tests conducted on powder coating applications are generally classified into three main categories:
1️⃣ Physical tests
2️⃣ Mechanical tests
3️⃣ Chemical and environmental resistance tests

⚙️ 1. Physical Tests
These tests focus on the surface quality and coating thickness.

Coating Thickness Measurement:
The thickness of the coating (typically 60–120 microns) is measured using specialized devices.
The uniformity of the application and compliance with standards are checked.

Gloss Measurement (Gloss Test):
The light reflection of glossy or matte surfaces is measured.

Color Matching (Color Test):
The post-production color is compared with a reference color chart.
Color difference is determined using the ΔE value.

🛠️ 2. Mechanical Tests
These tests assess the physical durability of the coating.

Adhesion Test (Cross Hatch Test):
Cuts are made on the coated surface and tape is applied and removed.
The rate of coating detachment is evaluated.

Impact Resistance Test (Impact Test):
A hammer is dropped from a specific height onto the surface.
The coating is checked for cracks or damage.

Bending Test (Cylindrical Bend Test):
The coated metal is bent around a cylinder of specific diameter.
Elasticity and crack resistance of the coating are assessed.

Scratch Resistance Test:
Pressure is applied to the surface to measure scratch resistance.

🌦️ 3. Chemical and Environmental Resistance Tests
These tests determine the long-term durability of the powder coating.

Salt Spray Test:
Coated surfaces are exposed to a saline environment for an extended period.
Corrosion resistance and coating integrity are evaluated.

Humidity Test:
The coating is tested under high humidity and temperature.
Resistance to water vapor is measured.

UV Resistance Test (Weathering Test):
Color fading and surface deterioration under UV exposure are observed.
Important for coatings intended for outdoor use.

Chemical Resistance Test:
Surface changes after exposure to acids, alkalis, and solvents are examined.

💡 Summary Table:

Test Type Purpose Measured Property
🧩 Coating Thickness Coating standard Micron measurement
✨ Gloss & Color Visual quality Color difference, gloss
🛠️ Adhesion / Impact / Bend Mechanical durability Surface integrity
🌦️ Salt Spray / Humidity / UV Environmental resistance Corrosion and fading resistance
⚗️ Chemical Test Resistance check Effect of acids and solvents

💬 Conclusion:
Powder coating tests ensure that coatings meet quality, durability, and aesthetic standards.
These tests allow manufacturers to provide long-lasting, reliable, and high-performance coatings to customers.

⚠️ Precautions for Powder Coating Application

🧼 1. Surface Preparation is Crucial

The surface must be completely free from oil, dirt, rust, and moisture before coating.

• Use chemical methods (phosphating, chromating) or mechanical methods (sandblasting) for cleaning.

• Insufficient surface preparation can cause peeling or blistering of the coating.

🌡️ 2. Parts Must Be Properly Dried
No moisture should remain on the cleaned surface.

• Applying paint on a wet surface can lead to bubbling and peeling under the coating.

• Parts must be thoroughly dried in a drying oven or with hot air.

⚙️ 3. Application Environment Must Be Clean and Controlled

• The coating booth must be free from dust, oil vapors, or contaminated air.

• Humidity should be around 40–60%, and temperature 20–25°C.

• Avoid static electricity buildup in the environment.

🎯 4. Powder Coating Application Settings Must Be Correct

• Gun voltage, air pressure, and powder flow should be adjusted according to the product type.

• Too high voltage causes powder bounce-back; too low voltage results in insufficient coverage.

• The distance between the gun and the surface should be 15–25 cm.

🔥 5. Curing (Baking) Time and Temperature Must Be Controlled

• Follow the temperature and time specified by the manufacturer for each powder coating.
  (Typically 180°C / 10–20 minutes)

• Oven temperature must be uniform; overheating can cause color change.

• Under-curing reduces coating durability.

🧤 6. Application Personnel Must Be Trained and Careful

• Operators should be knowledgeable about powder coating equipment, gun settings, and safety procedures.

• Use protective equipment (mask, gloves, goggles) against static electricity, fire, or inhalation of powder.

♻️ 7. Recovery and Cleaning Must Be Regularly Performed

• Overspray powder in the booth should be collected and reused via the filtration system.

• Booth, filters, and guns must be cleaned routinely and completely emptied when changing colors.

• Pay attention to color transitions to prevent mixing of different colors.

💡 Summary Table:

Category Precautions
🧼 Surface Preparation Completely remove oil, rust, and moisture
🌡️ Drying Ensure surface is fully dry
⚙️ Environment Clean, controlled humidity and temperature
🎯 Application Settings Proper voltage, pressure, and distance
🔥 Curing Correct time and temperature
🧤 Safety Use mask, gloves, and goggles
♻️ Recovery Clean filters, manage color changes carefully

💬 Conclusion:
Successful powder coating application depends on careful surface preparation, correct application settings, and proper curing conditions.
When these steps are followed, the coating will be durable, aesthetically pleasing, and long-lasting.

📦 Packaging and Storage Conditions for Powder Coatings

🧰 1. Packaging Method

Powder coatings are typically packed in 25 kg double-layer kraft bags or airtight cardboard boxes.

• Inside: moisture-resistant polyethylene bag

• Outside: sturdy cardboard

The packaging must include the following information:

• Manufacturer name

• Color code and batch number

• Production date and expiration date

• Recommended application temperature and curing time

📌 Purpose: To protect the powder from external factors (moisture, dust, heat) and ensure long-term storage.

🌡️ 2. Storage Environment
Powder coatings should be stored in cool, dry, and well-ventilated areas.

• Storage temperature: 20–25°C

• Relative humidity: below 50%

• Keep away from direct sunlight, heat sources, and damp floors

• Bags should be stored on pallets, off the ground

⚠️ High temperature and humidity can cause clumping and loss of electrostatic properties.

⏳ 3. Shelf Life

• Under proper conditions, the shelf life of powder coatings is typically 12 months.

• Products past their shelf life should be tested before use.

• During hot months, use the first-in, first-out (FIFO) principle if warehouse temperatures rise.

🔄 4. Precautions Before Use

• Allow unopened packaging to reach room temperature (approx. 2–3 hours) before opening.

• Opening cold storage product immediately can cause condensation.

• Opened packaging should be tightly sealed and used promptly.

💡 Summary Table:

Criteria Proper Condition / Precaution
📦 Packaging 25 kg double-layer bag or box
🌡️ Storage Temperature 20–25°C
💧 Humidity Below 50%
☀️ Environment Dry, ventilated, away from sunlight
🧺 Placement On pallets, off the ground
⏳ Shelf Life Approx. 12 months
🔄 Before Use Bring to room temperature before opening

💬 Conclusion:
Proper packaging and storage maintain the quality, flowability, and electrostatic properties of powder coatings.
This ensures uniform coating, consistent color, and high performance during application.

📘 Electrostatic Powder Coating Glossary

🔹 A – D Letters

Flow (Akışkanlık):
The ability of powder coating to melt and spread evenly on the surface. Important for a smooth finish.

Aluminum Phosphating (Alüminyum Fosfatlama):
Chemical surface treatment on aluminum to improve paint adhesion.

Primer Powder Coating (Astar Toz Boya):
Powder coating applied before the topcoat to enhance corrosion resistance.

Burr (Çapak):
Sharp or rough protrusions on metal surfaces. Must be removed before coating.

Cross Hatch Test (Çentik Testi):
A cut-and-tape test to measure the adhesion strength of the coating.

Impact Test (Darbe Dayanım Testi):
Test to assess the coating's resistance to mechanical impacts.

Discharge (Deşarj):
Sudden release of electrostatic charge from a surface, which can cause uneven powder adhesion.

🔹 E – K Letters

Electrostatic Charge (Elektrostatik Yük):
Electrical charging of powder particles, enabling them to stick to metal surfaces.

Epoxy Powder Coating (Epoksi Toz Boya):
Powder coating with high chemical and mechanical resistance, commonly used indoors.

Epoxy-Polyester Powder Coating (Epoksi-Polyester Toz Boya):
A hybrid coating combining epoxy and polyester resins for durability and decorative finish.

Film Thickness (Film Kalınlığı):
The thickness of the coating layer after application (typically 60–120 μm).

Curing / Baking (Fırınlama / Kürleme):
Process in which powder coating melts and polymerizes under heat, ensuring adhesion and durability.

Phosphating (Fosfatlama):
Chemical surface treatment to prepare metal for coating.

Recovery System (Geri Kazanım Sistemi):
Collects overspray or non-adhered powder for reuse.

Gloss (Parlaklık):
The light-reflecting property of the surface. Levels include high gloss, semi-matte, and matte.

🔹 L – P Letters

Booth (Kabin / Boya Kabini):
Enclosed area where powder coating is applied under controlled conditions.

Mil Gauge (Kalınlık Ölçer):
Device used to measure the coating's film thickness.

Curing (Kürleme):
Process in which powder particles melt at high temperature to form a hard, durable film.

Matness (Matlık):
The degree to which a surface reflects light; controlled for desired aesthetics.

Humidity Test (Nem Testi):
Laboratory test measuring coating resistance under high humidity conditions.

Polymerization (Polimerizasyon):
Chemical hardening of powder resin under heat.

Polyester Powder Coating (Polyester Toz Boya):
UV- and weather-resistant coating, suitable for exterior applications.

🔹 R – Z Letters

Color Difference (ΔE / Renk Farkı):
Difference between applied coating color and reference color; measured for color consistency.

Moisture / Humidity (Rutubet / Nem):
Water vapor in storage or application environment; can affect powder clumping.

Static Electricity (Statik Elektrik):
Electrical energy generated by electrostatically charged powder particles.

Spray Gun (Tabanca / Elektrostatik Püskürtme Tabancası):
Equipment that electrostatically charges powder and sprays it onto surfaces.

Thermoset Powder Coating (Termoset Toz Boya):
Powder coating that permanently hardens when heated and cannot be re-melted.

Salt Spray Test (Tuz Püskürtme Testi):
Long-term test to assess corrosion resistance of the coating.

UV Resistance (UV Dayanımı):
Ability of the coating to retain color and gloss under ultraviolet exposure.

Adhesion (Yapışma):
The strength with which the coating layer sticks to the surface.

Surface Preparation (Yüzey Hazırlığı):
General term for cleaning, phosphating, or sanding performed before coating.