TECHNICAL APPLICATION GUIDE.

TECHNICAL APPLICATION GUIDE

The First Step to a Perfect Coating: Professional Surface Preparation

Proper surface preparation is critical to achieving the best performance from paint application, extending coating life, and obtaining an attractive appearance. At Dekoral Boya, we offer you the most suitable methods.

Excellent Adhesion

A clean, smooth surface allows paint to adhere firmly and helps prevent blistering and peeling.

Long-Lasting Protection

Proper preparation helps the coating protect the surface from external factors, moisture, and rust for longer.

Aesthetic Appearance

Removing surface defects helps the topcoat achieve a smooth, uniform, professional appearance.

Preparation Guide by Surface Type

Steel Surfaces

Structural Steel Surfaces

• 1. Chemical cleaning: Completely remove oil, grease, and similar substances from the surface with suitable chemicals (detergent or solvent). Then wash with high-pressure water and dry.
• 2. Abrasive blasting: If the cleaned surface has no coating, blast it to at least Sa 2 ½ in accordance with TS EN ISO 8501-1. This process removes rust and mill scale.
• 3. Mechanical cleaning: Where abrasive blasting cannot be performed, clean to St 3 using mechanical tools such as a wire brush.
• 4. Priming: After cleaning, remove dust from the surface and apply the primer coat within 4 hours at the latest, depending on ambient conditions.

Light-Gauge Steel Surfaces

After oil, dirt, and dust have been removed, sand the surface uniformly with 120–180 grit abrasive to prepare it for painting.

Aluminium Surfaces

Basic Methods for Aluminium

Contaminants such as oil, dirt, and rust on aluminium surfaces are removed by chemical methods. Inadequate cleaning can lead to problems such as blistering beneath the paint and premature rusting.

Alkaline Degreasing

Alkaline solutions are used to remove organic contaminants (oil and grease) from the surface. They dissolve the oils and remove them from the surface.

Acid Cleaning

Acidic solutions remove oil, rust, and dirt from metal surfaces. This method also slightly roughens the surface, creating a better bonding surface for primer and paint.

Important note: After chemical cleaning, rinse the surface thoroughly with clean water and ensure it is completely neutral before beginning the coating or painting process.

Wall and Concrete Surfaces

Wall and Concrete Preparation Steps

• 1. Surface cleaning: Remove dirt, dust, oil, and other contaminants with water or suitable chemical cleaners. Pressurised water may be used if necessary.
• 2. Repairs: Fill defects such as cracks and holes with suitable repair mortar or filler, then sand the surface smooth.
• 3. Drying: Allow the surface to dry completely after cleaning and repairs. Measuring moisture before painting is recommended on large surfaces. Never apply to a damp surface.
• 4. Priming: Apply a suitable Dekoral impregnating primer or transition primer to help the paint adhere better and provide a more uniform appearance.

Professional Paint Repair Procedures

Mechanical damage, weld burns, or moisture-related problems that develop over time can weaken a coating’s protective and aesthetic properties. The source recommends restoring painted surfaces with the appropriate repair procedures.

Preventing Damage from Spreading

Repairing minor damage with the stated method can help prevent larger and more costly problems later.

Maintaining Protection

The source states that proper repair maintains the surface’s protection against corrosion and external factors.

Aesthetic Integrity

The source states that professional repair ensures the repaired area looks smooth and consistent with the original surface.

Repair Guide by Damage Type

Mechanical Damage

Repairing Mechanical Damage

These are defects in the topcoat caused by impacts, abrasion, or similar factors.

• 1. Topcoat damage only: If the damage is limited to the topcoat, sand the adjacent areas and apply topcoat to the damaged area by brush, roller, or spray.
• 2. Deep damage (less than 25 cm²): Remove the topcoat to a point extending 3 cm beyond the edges of the damaged area, then sand the edges. Fill the damaged area with fire-retardant paint using a spatula.
• 3. Topcoat application: After the intermediate coat has cured, apply topcoat over the entire area to complete the repair.

Weld Damage

Repairing Weld-Related Damage

• 1. Surface cleaning: Remove all paint to at least 5 cm beyond the edges of the damaged area.
• 2. Mechanical preparation and priming: Mechanically clean the exposed steel with a wire brush or abrasive blasting, then apply primer by brush.
• 3. Intermediate coat and topcoat: Apply an intermediate coat to the primed area with a brush or spatula. Once curing is complete, finish with the topcoat.

Moisture and Water Damage

Damage Caused by Moisture, Water, and Trapped Air

• 1. Removing blistered paint: Using a spatula and without excessive force, remove blistered and lifted paint layers as far as they can be removed.
• 2. Preparing the edges: Sand the sound topcoat remaining around the cleaned area, extending at least 3 cm outward, to remove the level difference.
• 3. Topcoat application: Depending on the size of the area, choose a spatula, brush, or spray application and complete the repair with topcoat.

Excellent Results with the Stated Application Conditions

The source states that paint application quality depends not only on the product itself but also on the conditions where it is applied and the equipment used. Dekoral Boya presents the following as ideal application conditions.

Optimum Drying

The source states that suitable temperature and humidity allow paint to cure in the stated time and condition, improving performance.

Preventing Surface Defects

The source states that ideal conditions help prevent application defects such as sagging, blistering, cracking, and surface marks.

Maximum Protection

The source states that correct application ensures the paint protects the surface to the highest degree against environmental factors.

Conditions by Application Method

General Ambient Conditions

Stated Ideal Application Environment

• Surface condition: Surfaces must be completely free of dust, dirt, and oil, and must be dry.
• Temperature: Ambient temperature must not be below 5°C, and surface temperature must not be below 7°C. Surface temperature must not exceed 50°C.
• Relative humidity: Relative humidity must not exceed 85%. The temperature of the surface to be coated must be at least 3°C above the dew point.
• Air movement: Wind speed must not exceed 24 km/h. Air movement in the area may assist drying.

Professional tip: Dehumidifiers or heaters may be used to bring the environment to the stated conditions. Note that gas heaters can increase ambient humidity.

Airless Spray-Gun Application

Application with an Airless Spray Gun

• 1. Equipment preparation: All spray equipment must be clean and in proper working order. Fit a suitable nozzle and set the pressure to 50–70 psi.
• 2. Paint mixing: Mix components A and B separately, then mix them together until homogeneous, without creating air bubbles.
• 3. Stripe coating: Before spraying, brush-coat welds, sharp edges, and corners, then allow them to dry for 10–15 minutes.
• 4. Thickness control: During application, regularly check wet-film thickness with a measuring gauge (comb). Areas with insufficient thickness should be completed within 36 hours.

Caution: The source states that mixed paint has a pot life of 6 hours at room temperature. Paint must not be used after this period.

Brush and Roller Application

Application by Brush and Roller

The source describes this method as ideal for narrow or small areas where an airless spray gun cannot be used.

• 1. Stripe coating: Before spraying large surfaces, coat weld seams, sharp corners, and edges with a brush or roller. The source states this helps provide uniform thickness.
• 2. Sufficient coats: For brush and roller application, apply the number of coats recommended by the manufacturer to achieve full coverage, as stated in the source.
• 3. Suitable equipment: The source states that using a quality brush and roller suited to the paint type helps prevent marks and produce a smoother result.