Highly durable coatings are assessed after use, not only immediately after application

When coating quality is checked, the first assessment often concerns appearance immediately after application.

Does the color match?
Is there sufficient gloss?
Is there contamination or dirt inclusion?
Is there sagging or unevenness?

Initial appearance is, of course, important.
However, it is insufficient for highly durable coatings.

What truly matters is whether the film retains its required performance after the product has actually been used.

Outdoor products are subjected to rain, ultraviolet light, moisture, temperature changes, salt, dust, stone impacts, and other stresses.
Even products used inside factories may be exposed to oil, chemicals, heat, wash water, impacts, and abrasion.

Highly durable coating therefore means more than simply applying a strong coating material.

It means anticipating damage in the use environment and designing a film that can withstand it.

Lessons from automotive finishing

Automotive finishing provides particularly useful lessons for highly durable coatings.

Consumers directly see automobiles.
They therefore require high appearance quality in color, gloss, distinctness of image, smoothness, and other properties.

Automobiles also spend long periods outdoors.
They experience many stresses, including rain, ultraviolet light, heat, moisture, stone impacts, salt, mud, washing, and oil.

Automotive finishing must therefore meet appearance and durability requirements together.

This approach is not limited to the automotive industry.

Similar durability is required for motorcycle parts, construction machinery parts, agricultural machinery parts, outdoor metal parts, building materials, factory equipment components, and other products.

The following point is the lesson to learn from automotive finishing.

Determine coating specifications by working backward from the stresses the product actually experiences.

Coating film damage from stone impacts

Automobiles, motorcycles, construction machinery, and agricultural machinery may be struck by small stones or sand while moving.

Chipping is the phenomenon in which such impacts cause the film to chip, crack, or peel.

Stone impacts cause more than surface scratches.

When the film chips, moisture and salt may enter through the damaged area and reach the metal substrate.
When moisture and oxygen reach the metal, rust begins there.

Stone impacts therefore cause appearance defects and also create an entry point for corrosion.

The underside of vehicle bodies, front sections, areas around fenders, suspension and undercarriage components, and exterior construction machinery parts are particularly susceptible to stones, sand, and mud.

A hard film alone is insufficient in these areas.
The film must be designed to resist cracking and peeling under impact and to make it difficult for damage to reach the substrate.

What is chip resistance?

Chip resistance is the ability of a film to resist cracking and peeling under impacts from stones, sand, and similar materials.

The important point is that simply making the film hard is not enough.

An excessively hard film may crack more readily under impact.
An excessively soft film, on the other hand, may scratch easily and have insufficient abrasion resistance.

A balance appropriate to the application is needed.

Improving chip resistance requires considering the following points.

• Primer adhesion
• Impact absorption by the intermediate coat
• Appropriate film thickness
• Intercoat adhesion
• Adhesion to the substrate
• Ensuring film thickness at edges and curved surfaces
• Coating specifications for individual areas

Areas prone to stone impacts, in particular, may require different coating specifications from other areas.
It is important to identify the performance needed in each area.

Corrosion risks from salt exposure

Salt damage is the phenomenon in which salt accelerates corrosion of metal.

For automobiles, use in coastal regions or deicing agents spread on roads in cold climates can be problematic.
In Vietnam as well, coastal areas, port surroundings, humid environments, and outdoor storage during the rainy season may increase corrosion risks from salt and moisture.

When salt attaches to metal together with moisture, it accelerates corrosion.
Small scratches or pinholes in the film may allow corrosion to progress from those locations.

When considering salt exposure, the main surfaces are not the only important areas.

The following locations readily become starting points for corrosion.

• Edges
• Around holes
• Welds
• Cut surfaces
• Bent areas
• Areas with thin coating film
• Scratched areas
• Areas where water tends to collect

When considering coating specifications, these vulnerable locations must be checked alongside flat surfaces.

Coating materials alone are insufficient against salt damage

Salt protection is often assumed to mean simply using a rust-preventive coating.

Such coatings are, of course, important.
However, they alone are insufficient.

Measures across the entire coating system are needed.

For example, the following factors are involved.

• Degreasing the substrate surface
• Removing rust and mill scale
• Conversion treatment or blast cleaning
• Rust-preventive primer
• Appropriate film thickness
• Barrier performance of the intermediate coat
• Weather resistance of the topcoat
• Repair of edges and cut areas
• Preventing scratches during transport
• Storage conditions after coating

In particular, insufficient surface preparation prevents adequate corrosion protection even when high-performing coating materials are used.

The film forms on the substrate surface.
If oil, rust, salt, or dust remains there, the film cannot achieve its intended performance.

Salt protection must therefore consider materials, surface preparation, film thickness, shape, storage, and repairs together.

Coating film deterioration from ultraviolet light

Ultraviolet deterioration is also important for outdoor products.

Ultraviolet light deteriorates resin at the film surface.
This may cause the following phenomena.

• Fading
• Discoloration
• Gloss loss
• Chalking
• Surface powdering
• Cracking
• Film embrittlement

Chalking occurs when the film surface deteriorates and becomes powdery.
It is often a problem with outdoor building materials, structures, and equipment exteriors.

Ultraviolet deterioration does not necessarily occur immediately.
It may become noticeable months or years after use begins.

For outdoor products, long-term weather resistance must therefore be considered alongside initial appearance.

Weather resistance is more than a topcoat issue

Weather resistance is the ability to withstand outdoor environments.

It generally refers to resistance to film deterioration from ultraviolet light, rain, temperature changes, moisture, atmospheric pollutants, and similar factors.

Weather resistance is strongly related to topcoat performance.
However, it is not determined by the topcoat alone.

For example, a poor underlying surface may cause peeling or blistering regardless of the topcoat’s weather resistance.
Insufficient film thickness makes the coating more susceptible to ultraviolet light and moisture.
An unsuitable recoating interval weakens intercoat adhesion and reduces long-term durability.

Check the following items when considering weather resistance.

• Topcoat weather resistance
• Compatibility with the primer
• Film thickness
• Intercoat adhesion
• Drying and curing conditions
• Substrate surface condition
• Service environment
• Maintenance interval

For outdoor products, it is important to consider weather resistance across the entire coating structure rather than the topcoat alone.

Required film performance differs by area

Even within the same product, different areas require different film performance.

For example, an automobile’s upper body surfaces, sides, underbody, front sections, and areas around the engine experience different stresses.

Upper body surfaces are readily affected by ultraviolet light and rain.
Front sections and underbody areas are readily affected by stone impacts and muddy water.
Use in coastal or cold regions also brings substantial salt exposure.
Areas around the engine may require resistance to heat and oil.

A single specification is therefore not necessarily appropriate for every area of the same product.

For highly durable coatings, examine the environment of each area and use different coating specifications where necessary.

This applies not only to automobiles but also to the following products.

• Construction machinery
• Agricultural machinery
• Outdoor equipment
• Structural steel components
• Distribution boards
• Material handling equipment
• Port equipment
• Architectural metalwork

Selecting specifications without examining stresses by area may cause particular locations to deteriorate early.

Film thickness control is fundamental to highly durable coatings

Film thickness control is particularly important for durability.

Insufficient thickness readily reduces rust protection, weather resistance, water resistance, and chip resistance.
Excessive thickness, on the other hand, causes sagging, drying defects, insufficient curing, cracking, and increased costs.

What matters is not simply applying a thick film.
It is consistently ensuring the required thickness in the required areas.

Particular care is needed in areas where film thickness tends to be low.

• Edges
• Corners
• Around holes
• Welds
• Recesses
• Back surfaces
• Contact points of hanging jigs
• Areas difficult to reach with the spray

These locations readily become starting points for corrosion or peeling.

Film thickness measurement must examine defect-prone areas as well as easily measured flat surfaces.

Surface preparation determines durability

Surface preparation is particularly important for highly durable coatings.

It is the process of cleaning and preparing the substrate before coating so that the coating material can adhere readily.

For metal, it includes degreasing, rust removal, conversion treatment, and blast cleaning.
For aluminum, oxide films and dedicated surface preparation need to be checked.
For plastics, mold release removal, surface modification, and primer treatment are important.

Insufficient surface preparation causes the following problems.

• Poor adhesion
• Rust
• Blistering
• Peeling
• Blistering
• Premature degradation

Where durability is required, surface preparation conditions must be checked before selecting coating materials.

In Vietnamese factories in particular, hot and humid conditions or outdoor storage may readily cause rust, moisture, or contamination on substrate surfaces.
A long waiting time after surface preparation can also cause recontamination or reoxidation.

Surface preparation is the invisible foundation of the film.
If this foundation is weak, adequate durability cannot be achieved even with high-performing coating materials.

Storage and transport after coating also affect durability

Management after the coating process is also important for highly durable coatings.

Even if coating is performed correctly in the factory, scratches afterward may become starting points for rust.
Stacking insufficiently dried products may cause marks, sticking, or blocking.
Exposure to rain outdoors may allow water to accumulate and cause corrosion or blistering.

Building materials and outdoor parts, in particular, face the following risks after coating.

• Scratches during transport
• Forklift contact
• Film damage from stacking
• Storage exposed to rain
• Condensation inside packaging
• Insufficient repairs at the installation site
• Unrepaired areas after cutting or drilling

These factors are separate from coating materials and application conditions.
However, they may ultimately be treated as coating defects.

Durable coating therefore requires management through storage, transport, installation, and repair.

Durable coating risks requiring particular attention in Vietnam

The following environmental conditions in Vietnam promote film deterioration.

• High temperature and humidity
• The rainy season
• Strong sunlight
• Salt in coastal areas
• Outdoor storage
• Dust inside factories
• Humidity during transport
• Condensation inside packaging
• Oil and chemicals around factories
• Differences in repair quality between operators

The influence of salt and moisture must not be underestimated, particularly in coastal areas or outdoor equipment.

During the rainy season, drying and storage after coating also require attention.
Exposure to humidity or moisture before the film is fully cured may cause blistering, whitening, or poor adhesion.

Stable highly durable coating requires consideration of coating materials, surface preparation, film thickness, drying, and storage based on Vietnam’s particular environment.

The 4M perspectives CoatureVietnam should check

CoatureVietnam uses the 4M perspectives when designing or improving highly durable coatings.

Material: Materials

• Does the coating material suit the use environment?
• Is a rust-preventive primer necessary?
• Does the topcoat have weather resistance?
• Is chip resistance required?
• Does the specification address salt exposure?
• Are the thinner’s drying properties appropriate?
• Is it compatible with repair materials?

Method: Methods

• Are the surface preparation conditions appropriate?
• Are film thickness standards clear?
• Are specifications differentiated by area?
• Are recoating intervals controlled?
• Are drying and curing conditions followed?
• Has a storage method after coating been established?
• Are repair procedures standardized?

Machine: Equipment

• Is the surface preparation equipment sufficient?
• Is booth airflow stable?
• Can the equipment deliver coating material to complex shapes?
• Is the temperature distribution in the drying oven stable?
• Is a film thickness gauge available?
• Can large parts be handled without scratching them?
• Is space available to avoid outdoor storage?

Man: People

• Do operators understand the effects of stone impacts, salt exposure, and ultraviolet light?
• Do they understand the importance of edges and areas around holes?
• Are repair coating decision criteria shared?
• Do they understand that insufficient film thickness leads to rust later?
• Do managers communicate the use environment to the shop floor?

The Management perspective is also important.

Durable coating requires managing customer requirements, warranty periods, recoating intervals, use environments, and complaint histories and reflecting them in coating specifications.

Questions to check during customer visits

When consulted about highly durable coatings, sales and technical personnel can use the following questions.

• Will the product be used indoors or outdoors?
• Will it be used in coastal areas or humid environments?
• Are any areas exposed to stone impacts, abrasion, or shocks?
• Will it be exposed to ultraviolet light for long periods?
• Where have rust or peeling complaints occurred?
• How long after use begins do defects appear?
• What surface preparation method is used?
• Are edges and cut areas repaired?
• Where is film thickness measured?
• Are products stored indoors or outdoors after coating?
• Does film damage occur during transport?
• Has the customer specified a required durability period?

These questions help organize durability issues that cannot be identified from coating materials alone.

Summary: Work backward from the use environment for highly durable coatings

Stone impacts, salt exposure, and ultraviolet light place substantial stress on coating films.

Stone impacts damage the film and create entry points for corrosion.
Salt accelerates corrosion together with moisture.
Ultraviolet light deteriorates the surface and causes fading, gloss loss, and chalking.

Selecting a strong coating material alone is insufficient to withstand these stresses.

Surface preparation, primers, intermediate coats, topcoats, film thickness, specifications by area, drying conditions, storage methods, and repair rules must be considered together.

Highly durable coatings are assessed after use rather than only immediately after application.

CoatureVietnam sees coating as a process supporting the lifetime and reliability of customers’ products rather than merely a surface treatment.

Coating the Future with Science and Care

To put this into practice, it checks where the product is used, what it is exposed to, and which qualities must be maintained for how long, and supports film design suited to the application.