Customers buy the coating film’s functions, not the coating material

In the coating business, we commonly speak of “selling coating materials.”

However, what customers truly need is not the can of material itself.
They want the value delivered after the material is applied to the product surface, dries and cures, and becomes a coating film.

For example, customers want the following kinds of value.

• Greater resistance to rust
• The ability to withstand heat
• The ability to withstand chemicals
• A surface that does not conduct electricity
• Conversely, a surface that conducts electricity
• A surface that slides more easily
• Greater resistance to wear
• Greater resistance to dirt
• Suppression of bacteria and mold
• A more attractive appearance
• Longer product service life
• Fewer customer complaints

What customers want is therefore not the coating material, but the functionality and confidence provided by the coating film.

Material in a can is not yet the finished product.
It functions as a coating film only after application to the substrate at an appropriate thickness and correct drying and curing.

Misunderstanding this weakens proposals for functional coating materials.

“This material is heat resistant.”
“This material prevents rust.”
“This material is electrically conductive.”

These explanations alone are insufficient.

What must actually be checked is
whether the material consistently delivers the required functions when it forms a film under the customer’s operating conditions
.

What is a functional coating film?

A functional coating film gives a product surface specific functions in addition to simply adding color.

Typical examples include the following.

• Rust-resistant coating films
• Corrosion-protective coating films
• Heat-resistant coating films
• Chemical-resistant coating films
• Electrically insulating coating films
• Electrically conductive coating films
• Electromagnetic shielding coating films
• Low-friction coating films
• Lubricating coating films
• Wear-resistant coating films
• Antibacterial coating films
• Mold-resistant coating films
• Dirt-resistant coating films
• Heat-reflective coating films
• Photoluminescent coating films
• Flame-retardant coating films
• Photocatalytic coating films
• Decorative coating films

None of these is complete simply because the material has been applied.

A functional coating film is achieved only when materials, processes, equipment, the service environment, and evaluation methods are properly aligned.

For example, rust can occur despite using a rust-resistant coating material if surface preparation is poor.
A heat-resistant coating material will not perform consistently if baking conditions or film thickness are unsuitable.
An insulating coating material may suffer insulation failure if pinholes are present or film thickness is insufficient.
A conductive coating material may fail to achieve the intended resistance if film thickness or drying conditions are inappropriate.

Using a functional coating material and achieving a functional coating film are therefore not the same thing.

Why a functional coating material may fail to produce a functional film

A common problem with functional coating materials is a mismatch between catalog performance and the performance achieved on site.

The cause may lie in process conditions rather than the material itself.

Examples include the following.

• Insufficient surface preparation prevents adhesion
• Insufficient film thickness prevents the required function
• Excessive film thickness makes cracking more likely
• Insufficient drying or baking causes poor curing
• An unsuitable thinner produces a rough surface finish
• An unstable thinning ratio causes film thickness variation
• The material is poorly matched to the substrate
• The service environment is harsher than expected
• The evaluation method does not match customer requirements
• Trial production conditions differ from mass production conditions

In these situations, the shop floor often blames the coating material.
However, the conditions needed to bring out its functions may not actually have been established.

For functional coating films, the following question matters more than the material’s name.

Which process conditions are needed to achieve that function?

Basic conditions to check for functional coating films

Achieving a functional coating film requires checking at least the following conditions.

1. Intended purpose

The first point to establish is why the customer needs that function.

Even “heat resistance” can serve various purposes.

• Use on high-temperature parts
• Withstanding brief exposure to heat
• Withstanding a continuous service temperature
• Preventing heat-induced discoloration
• Preventing heat-induced adhesion failure
• Withstanding both heat and chemicals

Similarly, the specification needed for “rust resistance” changes with the service environment.

• Indoor use
• Outdoor use
• Coastal locations
• Hot, humid environments
• Chemical atmospheres
• Environments exposed to water
• Environments where scratching occurs easily

When proposing a functional coating film, establish its intended purpose before discussing material names.

2. Substrate

A coating film is always formed on some type of substrate.

A change in substrate changes the required surface preparation and material selection.

Examples of substrates to check include the following.

• Iron
• Galvanized steel sheet
• Aluminum
• Stainless steel
• Castings
• Resins
• Wood
• Glass
• Ceramics
• Composites

The same coating material may adhere to iron but adhere poorly to aluminum.
Resin substrates may present problems with solvent resistance or thermal deformation.
For galvanized materials, surface preparation and primer selection are important.

Functional coating films must be considered in relation to the substrate.

3. Surface preparation

Surface preparation is the foundation of a functional coating film.

Even a high-performance coating material will not deliver consistent film performance if surface preparation is insufficient.

The following surface preparation items should be checked.

• Degreasing
• Cleaning
• Sanding or polishing
• Blasting
• Phosphate treatment
• Conversion treatment
• Primer
• Surface roughness
• Moisture removal
• Residual oil
• Condition of the oxide film
• Adhered foreign matter

Surface preparation is especially important when considering rust resistance, adhesion, and durability.

Problems with functional coating films that appear to be material faults may actually result from insufficient surface preparation.

4. Film thickness

Film thickness control is extremely important for functional coating films.

Insufficient thickness may prevent the required function.
However, a thicker film is not necessarily better.

Excessive thickness may cause the following problems.

• Sagging
• Solvent popping
• Poor drying
• Cracking
• Poor adhesion
• Appearance defects
• Dimensional problems
• Higher costs

For example, a rust-resistant film may lack durability if the required thickness is not achieved.
Insufficient thickness in an insulating film may lead to insulation failure.
In a conductive film, thickness may affect electrical resistance.
An excessively thick low-friction film may affect dimensions or sliding behavior.

For functional coating films, thickness is not merely an inspection item; it is an important condition that determines functionality.

5. Drying and baking conditions

Film performance is also strongly affected by drying and baking conditions.

In particular, bake-curing and 2-component reactive coating materials cannot deliver their intended performance if curing is insufficient.

The following items should be checked.

• Drying temperature
• Drying time
• Baking temperature
• Baking time
• Heating-up conditions
• Temperature distribution in the oven
• Actual workpiece temperature
• Flash-off time
• Cooling conditions
• Conditioning time after drying

Catalog baking conditions must be understood in terms of the temperature actually reached by the workpiece, not simply the oven setpoint.

For example, with a thick metal part, its internal temperature may not rise immediately even when the oven temperature rises.
In this case, the setpoint differs from the actual workpiece temperature.

For functional coating films, control of drying and baking conditions is directly linked to performance.

6. Service environment

The performance delivered by a functional coating film changes with its service environment.

Environmental conditions to check include the following.

• Indoor or outdoor use
• High or ambient temperature
• Whether humidity is high
• Whether water reaches the surface
• Whether salt is present
• Whether chemicals contact the surface
• Whether wear occurs
• Whether ultraviolet light reaches the surface
• Whether oil or solvents contact the surface
• Whether there are electrical requirements
• Whether there are food, medical, or hygiene requirements

Vietnam has many conditions that are demanding for coating films, including high temperature and humidity, the rainy season, strong ultraviolet light, and coastal salt exposure.

A specification that caused no problems in Japan may need to be reassessed for the service environment in Vietnam.

7. Evaluation method

For functional coating films, the tests used to confirm performance must be decided in advance.

Examples of evaluation items to check include the following.

• Adhesion
• Film thickness
• Hardness
• Wear resistance
• Heat resistance
• Chemical resistance
• Water resistance
• Humidity resistance
• Weather resistance
• Salt spray testing
• Insulation resistance
• Surface resistance
• Coefficient of friction
• Dirt resistance
• Antibacterial properties
• Appearance
• Color difference
• Gloss

What matters here is which evaluation criteria the customer uses to decide acceptance or rejection.

If the manufacturer’s test method differs from the customer’s evaluation method, the interpretation of results also changes.
It is therefore important to confirm evaluation conditions before accepting an order or starting trial production.

Assessing functional coating films through 4M + Management

CoatureVietnam organizes functional coating films through 4M + Management.

Material: materials

For materials, we check how the coating material is designed to deliver its functions.

• Resin
• Pigments
• Additives
• Curing agent
• Thinner
• Functional ingredients
• Primer
• Undercoat
• Topcoat
• Coating material lot
• Storage conditions

For functional coating materials, compatibility with the substrate and process matters as well as the material’s own performance.

Method: methods

For methods, we check the coating process.

• Surface preparation method
• Thinning ratio
• Viscosity
• Application method
• Film thickness
• Number of coats
• Drying conditions
• Baking conditions
• Repair method
• Test method

Reproducible application conditions are important for functional coating films.
Even a successful trial will not deliver consistent performance if conditions change in mass production.

Machine: equipment

For equipment, we check coating and drying equipment.

• Spray gun
• Electrostatic coating machine
• Dip-coating equipment
• Coating material supply equipment
• Surface preparation equipment
• Cleaning equipment
• Drying oven
• Baking oven
• Film thickness gauge
• Test equipment
• Temperature measuring instruments

For functional coating films, variation in equipment conditions directly creates variation in performance.

Man: people

People’s understanding is also important.

• Can sales personnel establish the required functions?
• Can technical personnel design the process conditions?
• Can operators follow the conditions?
• Do quality personnel understand the evaluation method?
• Can managers transfer trial conditions into mass production?

Condition control is more important for functional coating films than for ordinary coating.
Everyone involved therefore needs to understand why each condition is necessary.

Management: management

Management requires integrated control of information.

• Customer requirements
• Service environment
• Coating specification
• Reasons for selecting the coating material
• Trial conditions
• Evaluation results
• Mass production conditions
• Defect history
• Process change history
• Customer approval history

For functional coating films, process changes may affect performance.
Changes to materials, thinner, film thickness, drying conditions, or equipment may therefore require reevaluation.

Points requiring particular attention in Vietnamese factories

Certain points require particular attention when handling functional coating films in Vietnamese factories.

1. Hot, humid environments

Vietnam has high humidity and a rainy season.
These conditions may affect rust protection, corrosion protection, adhesion, and drying conditions.

2. Outdoor storage

Parts or products stored outdoors are exposed to ultraviolet light, rain, moisture, dust, and salt.
Coating film deterioration must be considered.

3. Coastal salt exposure

Coastal locations have a risk of salt-induced corrosion.
Rust protection specifications, film thickness, and surface preparation become more important.

4. Oven temperature control

For bake-curing coating materials, checking oven temperature and workpiece temperature is important.
Judging only by the setpoint may allow undercuring to go unnoticed.

5. Operator training

For functional coating films, even a small deviation in conditions may affect performance.
Mass production quality will not be stable if operators do not understand what the conditions mean.

What sales personnel should check when proposing functional coating films

When consulted about a functional coating material, sales personnel should not begin by checking only the product name and price.

They should first ask the following questions.

• What functions are required?
• In which service environment are those functions needed?
• What is the substrate?
• What surface preparation is currently used?
• Is there a required film thickness?
• Is drying or baking equipment available?
• Are there specified service temperatures or chemicals used?
• Will the product be used indoors or outdoors?
• Which tests will determine acceptance or rejection?
• What mass production quantity is planned?
• Is there a customer approval process?
• What defects or difficulties are currently experienced?

Asking these questions turns a material sale into a proposal for coating film functions.

Coating is a technology for making things last longer

One of the most fundamental and important principles of functional coating films is making things last longer.

Metal rusts.
Resins deteriorate.
Wood changes under moisture and ultraviolet light.
Outdoor equipment is exposed to rain, sunlight, salt, and dirt.
Factory components are exposed to heat, wear, chemicals, oil, and moisture.

The coating film protects the substrate from these forms of deterioration.

Coating is therefore more than finishing.
It is a technology that extends product life, reduces maintenance costs, and gives customers confidence.

Rust-resistant, corrosion-protective, heat-resistant, and chemical-resistant coating all share the same underlying principle.

Enable products to be used longer, more safely, and more reliably.

This is an important value of coating films.

Surface functions such as photocatalysis also require condition control

Photocatalytic coating films are an example of functional coating films.

Photocatalysis uses light energy to cause chemical reactions at the surface.
Applications are considered in areas such as dirt resistance, antibacterial protection, mold prevention, deodorization, air purification, and water treatment.

However, applying a photocatalytic material does not guarantee an effect.

The following points must be checked.

• Under which light conditions is an effect expected?
• Is the application outdoors or indoors?
• Are the catalytic ingredients present at the surface in a state that allows them to function?
• What type of contamination is involved?
• Is durability sufficient?
• Is adhesion to the substrate satisfactory?
• Which tests will confirm the effect?

For advanced functions such as photocatalysis, service conditions and evaluation methods become even more important alongside the material’s name.

This principle applies to all functional coating films.

How CoatureVietnam can help

CoatureVietnam does not treat functional coating films as simply a sale of coating materials.

We identify the functions the customer requires and work together to organize the conditions needed to achieve those functions in the film.

We can support the following activities.

• Identifying required functions
• Checking the service environment
• Checking substrate and surface preparation conditions
• Selecting candidate coating materials
• Organizing film thickness conditions
• Checking drying and baking conditions
• Designing trial conditions
• Organizing evaluation methods
• Transferring conditions into mass production
• Analyzing causes when defects occur
• Considering alternative and local coating materials
• Preparing coating SOPs
• Preparing explanatory material for customers

CoatureVietnam aims for a relationship that goes beyond supplying coating materials.

We seek to understand the film functions customers require and deliver consistent product value, including through process conditions.

Summary

Material in a can is not yet the finished product.

It gains value only after application to the substrate at an appropriate thickness, correct drying and curing, and formation of a coating film.

Selecting a coating material alone is insufficient to achieve a functional film.

The following points must be checked.

• Intended purpose
• Substrate
• Surface preparation
• Film thickness
• Application method
• Drying and baking conditions
• Service environment
• Evaluation method
• Reproducibility in mass production

What customers truly want is not the coating material.
They want the functionality, service life, confidence, and product value delivered by the film.

The following perspective is important.

Go beyond selling coating materials to achieve coating film functions.
Coating is a technology that creates value on product surfaces.