What to consider before choosing an environmentally responsive paint

Certain topics frequently arise when reviewing a coating process.

“We want to reduce solvent-borne paint use.” “We want to switch to waterborne paint.” “We want to consider powder coating.” “We want to reduce VOCs.” “We want to reduce odors and fire risk.” “We want to improve the working environment.”

These are all very important topics.

Coating operations face many challenges, including solvent odors, flammability, burdens on workers, ventilation equipment, and regulatory compliance. Considering environmentally responsive options such as waterborne and powder coatings is therefore a natural step.

However, there is a point to bear in mind.

Waterborne and powder coatings are not always the best choice.

When choosing a paint form, consider not only environmental aspects but also coating film performance, equipment conditions, drying and baking conditions, workability, film thickness control, color changes, cleaning, costs, and the workload in daily operations.

Changing the paint form is more than a material change. It is a decision to change the entire coating process.

Each paint form has its own characteristics

The forms of paint used in industrial coating can broadly be classified as follows.

• Solvent-borne paint
• Waterborne paint
• Powder coating
• High-solids paint
• Solvent-free paint

Each has advantages. Each also has points that require attention.

The aim is not to decide which is best in general terms.

The aim is to determine which suits the factory, product, quality requirements, and equipment conditions concerned.

Characteristics of solvent-borne paints

Solvent-borne paints use organic solvents to dissolve or disperse resins and additives.

This form has long been used in industrial coating. It is used in many applications because it offers a manageable balance of application workability, drying characteristics, appearance, and coating film performance.

The main advantages of solvent-borne paints include the following.

• Often good application workability
• Drying characteristics are relatively easy to adjust
• Leveling is relatively easy to achieve
• Suitable for a wide range of resin systems
• Often easy to use with existing equipment
• Can facilitate high-quality appearance and high-performance films

There are also points that require attention.

• VOC emissions
• Odors
• Flammability
• Ventilation and explosion protection require consideration
• Occupational health and safety management is necessary
• Care is needed in storage, transport, and disposal
• Compliance with environmental regulations may be required

Solvent-borne paints can offer performance advantages. However, their working environment, safety, and environmental impacts often make them a target for improvement.

Characteristics of waterborne paints

Waterborne paints use water as their main medium.

They can make it easier to reduce VOCs and odors compared with solvent-borne paints. They are frequently considered for improving the working environment and addressing environmental requirements.

The main advantages of waterborne paints include the following.

• Easier VOC reduction
• Easier odor control
• Easier reduction of ignition risk
• Potential improvement of the working environment
• Easier communication of an environmentally responsible image

However, waterborne paints are not a universal solution.

There are points that require attention.

• Drying may take longer
• Greater sensitivity to temperature and humidity
• Defects are more likely where moisture cannot escape readily
• Water resistance must be checked
• Compatibility with surface preparation and the substrate must be checked
• Equipment may require corrosion prevention measures
• Wastewater treatment may be required
• Spray booths and drying equipment may need to be reviewed

Waterborne does not necessarily mean solvent-free. Waterborne paints can also contain co-solvents.

When considering waterborne paints, it is therefore necessary to check the extent of VOC reduction, safety, the capabilities of the drying equipment, and whether coating film performance requirements can be met.

Characteristics of powder coatings

Powder coatings are deposited onto the substrate by electrostatic attraction or other means and heated to melt and cure.

Because they use little or no solvent, they are an effective paint form for reducing VOCs.

The main advantages of powder coatings include the following.

• Potential for substantial VOC reduction
• Little solvent odor
• Thick films can be relatively easy to achieve
• Powder recovery can reduce waste
• Durable coating films can be produced
• Often recognized as an environmentally responsive coating method

Powder coatings also have points that require attention.

• Baking equipment is required
• Actual workpiece temperature control is important
• Films tend to be thick
• Thin-film control can be difficult
• Color changes can take time
• Powder recovery and cleaning require management
• Dust control is required
• Complex shapes can cause uneven film thickness
• May be difficult to use on materials vulnerable to low temperatures
• Small-lot production in many colors can increase the operational workload

Powder coating is a highly effective option. However, converting to powder coating requires more than changing the paint.

The system must be designed to include the powder booth, recovery equipment, baking oven, surface preparation, hanging fixtures, color-change operations, and cleaning rules.

Understanding high-solids paints

High-solids paints are generally formulated with a higher solids content and a reduced solvent content.

They may be considered as a way to reduce VOCs while retaining the workability and performance of solvent-borne paints.

Potential advantages include the following.

• Reduced solvent use
• Easier achievement of the required film thickness in a single coat
• Easier use of existing equipment
• A comparatively easier transition from solvent-borne paints

Higher solids content, however, can make viscosity control and application workability more difficult. Adjustments may be needed to control sagging, surface roughness, leveling, spray conditions, and drying conditions.

High-solids paints must also be evaluated for stable use under actual application conditions rather than judged simply on their lower VOC content.

Choosing solely for environmental reasons can create operational difficulties

Addressing environmental requirements is important. Reducing VOCs, odors, and fire risk and improving worker safety provide significant value in coating operations.

However, choosing a paint form solely for environmental reasons can create problems in daily operations.

For example, switching to waterborne paint may slow drying until it no longer fits the production cycle. Switching to powder coating may lengthen color-change times and make the process unsuitable for high-mix, low-volume production. A low-VOC paint may not produce a consistent surface with existing spray conditions. A substrate may not withstand the baking temperature after conversion to powder coating. Waterborne paints may produce more drying defects during humid periods.

Environmental performance, productivity, quality, and workability must therefore always be considered together.

What to check before considering a switch to waterborne paint

When considering waterborne paint, first check the following points.

• What is the application of the existing paint?
• What is the substrate material?
• Is the current surface preparation suitable for waterborne paint?
• Can the paint be used with the current application method?
• Is the drying equipment adequate?
• Can temperature and humidity be controlled?
• Does the drying time fit the production cycle?
• Does water resistance meet the requirements?
• Is adhesion satisfactory?
• Are there any wastewater treatment or equipment corrosion issues?
• How much VOC reduction can be achieved?

Switching to waterborne paint can improve the working environment. However, unsuitable drying or equipment conditions can make quality unstable.

What to check before considering a switch to powder coating

When considering powder coating, it is necessary to check equipment and operations as well as the paint.

Items to check include the following.

• Can the workpiece withstand the baking temperature?
• Is the required film thickness suitable for powder coating?
• Is the product shape suitable for powder coating?
• Can the required film thickness be achieved at corners and in recesses?
• Can a powder booth be installed?
• Is recovery equipment necessary?
• Does the baking oven have sufficient capacity?
• Can actual workpiece temperature be checked?
• Are many colors required?
• Are color changes frequent?
• Is the cleaning time acceptable?
• Is dust control adequate?
• Can operators be trained?

Powder coating is an excellent option for addressing environmental requirements. However, color changes and cleaning can become burdensome in high-mix, low-volume production with many colors and short lead times.

Conversion to powder coating must be considered as the design of an entire coating system rather than simply paint selection.

There is scope for improvement even when retaining solvent-borne paints

Environmental discussions tend to focus on switching to waterborne or powder coatings.

However, improvements are also possible while continuing to use solvent-borne paints.

Examples include the following.

• Considering higher-solids paints
• Selecting an appropriate thinner
• Standardizing the dilution ratio
• Improving transfer efficiency
• Optimizing spray conditions
• Improving local exhaust ventilation
• Reviewing drying conditions
• Reducing paint waste
• Reducing cleaning solvent use
• Improving worker protective equipment and ventilation

The issue is therefore more complex than labeling solvent-borne paints bad and waterborne or powder coatings good.

The important task is to determine which improvements are most practical and effective for the current problems.

Use the 4Ms to compare paint forms

CoatureVietnam uses the 4Ms to evaluate waterborne, powder, and solvent-borne options.

Material: materials

• Is the paint form suited to the application?
• Is adhesion to the substrate satisfactory?
• Can the required coating film performance be achieved?
• Have the effects of thinners and co-solvents been checked?
• Are powder storage conditions appropriate?
• Have the water resistance and drying characteristics of the waterborne paint been checked?

Method: methods

• Is the application method appropriate?
• Is dilution ratio or viscosity control required?
• Is flash-off time required?
• Are baking conditions clearly defined?
• Can color-change procedures be standardized?
• Do cleaning procedures fit the operational workload?
• Will film thickness control be stable?

Machine: equipment

• Can existing equipment be used?
• Is a new booth or drying oven required?
• Is powder recovery equipment required?
• Are corrosion prevention measures required for waterborne paint?
• Is drying capacity sufficient?
• Can actual workpiece temperature be checked?
• Are ventilation, exhaust, explosion protection, and dust controls adequate?

Man: people

• Can operators handle the paint safely?
• Can operators understand the new work procedures?
• Will color changes or cleaning increase the workload?
• Are quality acceptance criteria shared?
• Are protective equipment and safety training adequate?
• Can the system be operated sustainably in daily production?

Organizing the assessment this way makes it easier to identify the risks of changing paint form in advance.

Particular considerations in the Vietnamese market

The local environment is also important when evaluating paint forms in Vietnam.

Relevant conditions include the following.

• High temperatures and humidity
• Differences between the rainy and dry seasons
• Temperature and humidity control inside the factory
• Electrical and drying equipment capacity
• Operator training
• Ventilation equipment
• Dust conditions
• Salt damage in coastal areas
• Quality consistency of local paint manufacturers
• Lot-to-lot variation in components and substrates
• Capability for high-mix, low-volume production

Specifications that work well in Japan will not necessarily be stable when used unchanged in Vietnam.

Decisions in Vietnam must consider the climate, equipment, daily operations, and procurement conditions together.

Points to check on the factory floor

When considering waterborne conversion, powder conversion, or continued solvent-borne use, we check the following points.

• Is the objective to reduce VOCs, odors, or fire risk?
• Is improving the working environment the primary objective?
• Is reducing cost the primary objective?
• Is the change required by a customer?
• What defects or problems currently occur?
• What coating film performance is required?
• Can existing equipment accommodate the change?
• Can the necessary drying and baking conditions be achieved?
• Does the process fit the production cycle?
• Are color changes frequent?
• Is the process suited to high-mix, low-volume production?
• Will the burden on operators increase?
• Has the quality evaluation method been defined?
• Can the system be maintained after introduction?

How CoatureVietnam can help

CoatureVietnam supports paint form selection as the design of an entire coating process rather than a simple material change.

Paint Optimizer We review the conditions under which existing solvent-borne, waterborne, and powder paints are used to help stabilize quality, improve workability, and reduce environmental impacts.

Paint Voyager We identify suitable paint forms and candidate paints according to the application, substrate, service environment, and performance requirements.

Coat Systemizer We support the design of coating processes involving equipment changes, including powder coating, waterborne coating, and automated coating.

Thinner Streamer Even when retaining solvent-borne paints, we provide support on appropriate thinners, dilution ratios, drying characteristics, and improvements to the working environment.

Work standards and process control We help establish SOPs, work procedures, color-change procedures, film thickness controls, and inspection criteria after a change in paint form.

Summary

It is not easy to decide whether waterborne, powder, or solvent-borne paint is best.

Waterborne paints offer potential VOC and odor reductions. However, drying conditions, humidity control, water resistance, and wastewater treatment must be checked.

Powder coatings offer advantages in VOC reduction and thick-film formation. However, baking equipment, film thickness control, color changes, cleaning, and dust control are required.

Solvent-borne paints offer advantages in workability and appearance. However, VOCs, odors, flammability, and the working environment require attention.

The important point is to consider more than environmental performance alone.

Paint form must be selected by considering coating film performance, equipment, workability, safety, the environment, cost, and daily operations.

Coating the Future with Science and Care. CoatureVietnam helps find the most suitable choices for both environmental performance and production quality by considering not only paint but also processes, equipment, people, and management.