This article systematically introduces the concept, types, characteristics, formation principles, functions, application fields, selection considerations, and common problem-solving measures of wrinkle powder coatings. It focuses on the applications of wrinkle powder coatings to help everyone better understand what wrinkle powder coating is, as well as its characteristics and functions.
What Is Wrinkle Powder Coating
Wrinkle powder coating is a type of thermosetting powder coating that can form three-dimensional wrinkled or ripple-like textures after curing. It belongs to the category of artistic powder coatings and is also commonly known as sponge paint, water ripple paint, or orange peel powder coating.The formation of its texture mainly depends on the synergistic effect of the resin system, special wrinkle agents, and catalysts in the formulation during the curing process.
Types of Wrinkle Powder Coatings
According to the texture effect:1. Fine Wrinkle Type
The texture is delicate and uniform, similar to orange peel or fine sand texture. It has a smooth hand feel and is mainly used for precision instrument housings.
2. Coarse Wrinkle Type
The wrinkles have a strong three-dimensional effect with rough patterns. It has excellent ability to cover substrate defects and is commonly used for large workpieces such as electrical cabinets and industrial machinery.
3. Floating Pattern Type
The texture has obvious pigment separation or flower-like embossed effects, offering stronger decorative performance. It is mainly used for high-end furniture or display cabinets.
Characteristics of Wrinkle Powder Coating
The main characteristics of wrinkle powder coating are as follows:(1) Excellent Decoration and Concealing Performance
After curing, it forms a three-dimensional wrinkle texture that can effectively cover minor defects such as scratches, sand holes, and welding marks on the substrate surface. At the same time, it provides a delicate matte or semi-gloss texture, enhancing the product grade.
(2) Good Mechanical Protection Performance
The coating has high hardness and adhesion, with excellent scratch resistance and impact resistance. The dense texture structure can also block corrosive media, providing better corrosion protection than ordinary flat coatings.
(3) One-Time Coating Formation
Compared with traditional high-gloss flat coatings that require multiple spraying layers, wrinkle powder coating only requires one coating layer (the film thickness is usually controlled at 60–100 μm) to achieve both texture and protection effects. It eliminates the need for primer or intermediate coatings, resulting in higher production efficiency and lower costs.
(4) Sensitive to Application Conditions
The texture effect (such as wrinkle size and three-dimensional appearance) highly depends on curing temperature, film thickness uniformity, and baking time. Therefore, it has higher requirements for spraying process control, and the curing window parameters provided by the supplier must be strictly followed.
Formation Principle of Wrinkle Powder Coating
The basic principle of wrinkle powder coating is to utilize the difference in reaction rates between the melting flow and crosslinking curing processes of the coating film. Through the synergistic action of wrinkle agents and catalysts in the formulation, localized surface tension differences are artificially created, causing the initially cured areas to become “frozen” while the surrounding coating film that is still flowing undergoes shrinkage and accumulation. Finally, a three-dimensional wrinkle texture is formed and permanently fixed.The entire process can be specifically divided into three steps:
(1) Melting and Spreading
The powder melts into a liquid coating film when heated, and the surface tension is temporarily uniform.
(2) Dynamic “Freezing”
The wrinkle agent reduces the local surface tension, while the catalyst accelerates crosslinking in this area, causing the viscosity to increase sharply and the fluidity to disappear. Meanwhile, the surrounding unaffected areas continue to level. This difference in surface tension and curing speed drives the coating film to shrink and accumulate, forming a concave-convex texture.
(3) Permanent Shaping
Continued baking allows the entire coating to completely crosslink and cure, permanently locking the texture.
Functions of Wrinkle Powder Coating
The main functions of wrinkle powder coating are specifically reflected in the following aspects:(1) Decorative Enhancement Function
By forming a three-dimensional wrinkle texture, it provides workpieces with a delicate matte or semi-gloss texture, improves appearance quality, and is commonly used on the surfaces of household appliances, furniture, and industrial equipment.
(2) Physical Protection Function
The cured coating has excellent hardness, scratch resistance, and impact resistance. At the same time, the dense texture structure can effectively block moisture and corrosive media, extending the service life of the substrate.
(3) Substrate Defect Concealing Function
The raised and recessed texture can effectively cover processing defects such as scratches, welding marks, and sand holes on metal surfaces, reducing the requirements for substrate pretreatment accuracy and improving product yield.
(4) Simplifying the Coating Process
Only one spraying process and one baking process are required to complete the coating formation, eliminating primer or intermediate coating layers. While ensuring performance, it saves working time and reduces costs.
Application Fields of Wrinkle Powder Coating
Wrinkle powder coating has extremely wide application fields. The main application areas are as follows:
1. Household Appliance Field
It is widely used in refrigerators, washing machine side panels, outdoor air conditioner units, and microwave oven housings. The texture is used to cover metal stamping scratches and provide a matte texture that can withstand daily wiping.
2. Office and Commercial Equipment Field
It is commonly used for filing cabinets, safes, cashier counter panels, and display shelves. It provides equipment with wear-resistant and scratch-resistant hard surfaces while enhancing the visual quality of commercial environments.
3. Industrial Electrical and Machinery Field
It is widely used for electrical cabinets, control cabinets, machine tool housings, and industrial sewing machine tables. The thick coating texture effectively conceals welding marks and provides excellent corrosion resistance and impact protection.
4. Construction and Outdoor Facility Field
It is applied to aluminum alloy doors and windows profiles, security doors, courtyard fences, and outdoor furniture. Weather-resistant polyester systems are used to ensure that the texture remains clear and resistant to chalking after long-term exposure to sunlight.
How to Select Wrinkle Powder Coating
When selecting wrinkle powder coating, we may face the problem of not knowing how to choose. Based on our industry experience, we recommend focusing on the following aspects when selecting wrinkle powder coating.1. Consider the Application Environment
(1) Indoor Applications
Choose epoxy/dicyandiamide systems, which have lower costs and strong adhesion, suitable for electrical control cabinets, office furniture, and other applications.
(2) Outdoor Applications
Polyester/TGIC or polyester/TMMGU systems must be selected. They provide excellent weather resistance and UV aging resistance, and are suitable for security doors and outdoor furniture.
2. Consider Texture Fineness
(1) Fine Wrinkle / Sand Texture
The texture is delicate and uniform with a smooth hand feel. It is suitable for applications requiring a refined touch, such as precision instruments and household appliance panels.
(2) Coarse Wrinkle / Floating Pattern
It has a strong three-dimensional effect and rough patterns, with excellent ability to cover substrate defects. It is suitable for workpieces such as electrical cabinets and large machinery that require a strong industrial style or need to conceal surface imperfections.
3. Consider Workpiece Shape
(1) Complex Workpieces (with Grooves and Inner Corners)
Fine wrinkle type is recommended because it has better leveling performance and is less likely to cause exposed substrate areas or uneven textures at edges and corners.
(2) Large Flat Panels
Both coarse wrinkle and fine wrinkle types can be used, but attention should be paid to film thickness uniformity; otherwise, color differences may easily occur.
4. Consider Color and Gloss
Wrinkle coatings are generally matte finishes (60° gloss is usually ≤40%).
(1) Light Colors (White, Gray)
They can highlight the layered texture effect, but have weaker hiding power, so the film thickness needs to be appropriately increased.
(2) Dark Colors (Black, Dark Blue)
They provide a stronger three-dimensional texture effect, but are affected by the oil absorption of pigments, requiring adjustment of the amount of wrinkle agent in the formulation.
(3) High-End Products
Metallic sparkle effects can be customized (by adding aluminum powder), but this will reduce the ability to conceal defects.
Common Problems and Solutions of Wrinkle Powder Coating
The most common problems encountered during the use of wrinkle powder coating are mainly reflected in the following aspects. Based on our industry experience, we propose corresponding solutions to help effectively solve the powder coating problems you may encounter.1. Uneven Texture or Texture Disappearance
This is the most common problem.
Possible causes:
Fluctuations in curing temperature (excessively high temperature causes the texture to become shallow or disappear, while low temperature causes the texture to become too coarse), uneven coating thickness (thicker spraying produces larger patterns, while thinner spraying may expose the substrate), or an incompatible resin system.
Solutions:
Strictly control the oven temperature within the supplier-recommended range of ±5℃, ensure that the film thickness remains stable at 80–120 μm, and select polyester resins with suitable acid value and viscosity.
2. Pinholes and Fine Cracks
Small depressions or abnormal textures appear on the coating surface.
Possible causes:
Cross-contamination of powders from different systems (interface formation caused by differences in curing rates), water vapor generated during curing of HAA systems that fails to escape in time, or uneven dispersion of pigments and fillers.
Solutions:
Thoroughly clean the equipment when changing colors during production; add degassing agents such as benzoin and amide wax into HAA system formulations to promote the release of water vapor.
3. Substrate Exposure and Insufficient Hiding Power
The coating cannot completely cover the substrate, or the base color is exposed at the raised areas of the wrinkle texture.
Possible causes:
Low resin content (<55%), poor wettability, or weak hiding power of the powder itself (especially obvious in light-colored systems).
Solutions:
The resin ratio can be appropriately increased, 0.5% wetting agent can be added to improve melting wettability, and sufficient coating film thickness should be ensured.
4. Coating Delamination (Poor Adhesion)
It commonly occurs on recoated workpieces and appears as large-area peeling of the coating.
Possible causes:
The surface tension of the bottom sand-textured coating layer is too low (containing polytetrafluoroethylene-based texture agents or excessive wax), over-curing causes a lack of active groups for crosslinking with the recoating layer, or poor resin quality (containing low molecular weight substances).
Solutions:
Control the curing degree of the bottom coating layer to avoid over-curing, remove surface contaminants, and ensure that the bottom layer is properly sanded before recoating to increase mechanical anchoring force.
5. Unstable Performance of Recycled Powder
Possible causes:
Recycled powder may contain partially crosslinked resin or impurities, causing abnormal texture effects in newly sprayed coatings.
Solutions:
It is recommended to mix recycled powder with new powder at a fixed ratio (generally no more than 20%–30%) and conduct a trial spray test on sample panels first to confirm the effect.
If you encounter some difficult problems during the use of wrinkle powder coating, please feel free to contact us at any time to obtain professional technical support, discuss solutions together, and promote the development of the powder coating industry.
We hope this article can provide you with a professional and reliable reference regarding the powder coating industry. We sincerely welcome you to consult us regarding product performance, industry standards, application methods, precautions, or any related questions about powder coating products. We look forward to your inquiries through messages or direct contact at any time, so that we can provide you with more detailed product information, demonstration videos, or customized solutions to help you fully understand the functions and advantages of our products.
