What to examine first when you want to reduce paint costs

We sometimes receive requests to reduce paint costs in a coating process.

The first focus is often the paint’s unit price.
Is there a cheaper paint?
Can we switch to a local product?
Can we negotiate with the supplier?

Paint unit price is certainly important.
However, looking only at unit price is insufficient to genuinely reduce coating process costs.

This is because not all the paint used adheres to the product.

In spray coating, some of the sprayed paint adheres to the product.
However, some disperses in the air, deposits on booth walls and floors, is captured by filters, or moves toward the exhaust, ultimately requiring cleaning or disposal.

The following perspective is therefore needed when considering paint costs.

How much of that paint remains as a coating film on the product?

This is the concept of transfer efficiency.

What is transfer efficiency?

Simply put, transfer efficiency is the proportion of paint used that actually adheres to the workpiece and becomes coating film.

For example, if 100 units of paint are used, 50 adhere to the product, and the remaining 50 are dispersed, discarded, or deposited on the booth, half of the paint has not become product value.

This is more than a material loss.

Paint that does not adhere to the product leaves the following burdens on the shop floor.

• Contamination inside the booth
• More frequent filter replacement
• More cleaning labor
• More waste paint and used filters
• Risk of operator exposure to paint mist
• A higher load on exhaust equipment
• Higher equipment maintenance costs
• Greater environmental impact from VOCs and waste

Low transfer efficiency may therefore increase associated costs as well as paint expenditure.

To assess coating costs correctly, it is necessary to consider paint consumption, paint loss, cleaning, disposal, maintenance, and the working environment, rather than paint unit price alone.

Before buying cheaper paint, check whether it is being used without waste

Paint cost reduction tends to become a search for cheaper paint.

However, switching to cheaper paint while transfer efficiency remains low may not address the underlying issue.

Examples include the following.

• Operators apply thicker films than necessary
• The spray distance is too great, so paint disperses before reaching the product
• Air pressure is too high, causing excessive spread of paint mist
• Booth air velocity is too high, carrying paint toward the exhaust
• Poor fixtures or hanging arrangements create many areas that are difficult to coat
• Product spacing is too narrow, increasing wasted spray
• Application techniques differ between operators, making consumption unstable

In these cases, reviewing application conditions can produce a larger improvement than reducing paint unit price.

Buying paint cheaply is also important.
However, there is something to check first.

Is the paint currently used being deposited on the product without waste?

This question is the starting point for coating improvement.

Main factors that reduce transfer efficiency

Transfer efficiency is not determined by a single cause.
Paint, application methods, equipment, workpieces, operators, and management methods interact in complex ways.

CoatureVietnam organizes these factors through 4M + Management.

1. Material: Paint and thinner conditions

Paint condition has a major effect on transfer efficiency.

For example, excessively high viscosity can cause poor atomization and a rough coating surface.
Conversely, excessive dilution reduces solids content and may require more application passes or paint to achieve the necessary film thickness.

If thinner drying speed is unsuitable, the paint may dry too much before reaching the product, or it may cause sagging or surface roughness.

The main items to check are as follows.

• Paint viscosity
• Dilution ratio
• Solids content
• Drying speed
• Thinner used
• Paint stirring condition
• Pot life
• Electrical resistance for electrostatic coating
• Particle size and charging characteristics for powder coatings

Paint is not a material that can simply be sprayed without further consideration.
A stable coating film is achieved only when the paint is used in a condition suited to the coating method and shop-floor conditions.

2. Method: Application methods and operating conditions

Application methods directly affect transfer efficiency.

In air spray coating in particular, differences in operator skill greatly affect paint consumption.

Even with the same product, paint, and spray gun, the following conditions may vary between operators.

• Spray distance
• Gun angle
• Gun travel speed
• Paint delivery rate
• Air pressure
• Overlap width
• Application sequence
• Amount of off-target spray
• Approach to achieving target film thickness

Paint consumption will not stabilize if these conditions are not standardized.

Film thickness may also exceed what is necessary.
A thicker coating does not necessarily provide reassurance.
Excessive film thickness can cause sagging, drying defects, solvent popping, cracking, and poor adhesion, as well as increasing paint costs.

Improving transfer efficiency requires standardized application conditions rather than relying solely on operators’ intuition.

3. Machine: Application equipment, booths, and equipment conditions

Coating equipment also has a major effect on transfer efficiency.

For example, poor spray gun atomization prevents uniform paint deposition on the product.
Excessive air pressure spreads fine paint mist too widely, making dispersion without deposition more likely.

Booth air velocity is also important.

If booth air velocity is too low, mist can return toward the operator.
If it is too high, paint may be carried toward the exhaust before adhering to the product.

For electrostatic coating, grounding and fixture condition are also important.
Even with an electrostatic gun, the intended transfer efficiency cannot be achieved if workpiece grounding is inadequate.

Check the following equipment items.

• Spray gun condition
• Nozzle and air cap wear
• Air pressure
• Paint delivery stability
• Paint supply equipment
• Booth air velocity
• Supply and exhaust air balance
• Filter condition
• Fixture electrical continuity
• Grounding for electrostatic coating
• Drying and baking oven conditions

New application equipment does not necessarily increase transfer efficiency on its own.
Correct management of equipment conditions is a prerequisite.

4. Man: Operators, skills, and training

Operator skill strongly affects transfer efficiency.

Experienced operators may produce the required film thickness with less paint.
Less experienced operators may apply too much out of uncertainty or repeatedly spray areas that are difficult to coat.

Leaving this as an individual difference prevents paint consumption from stabilizing.

The priority is not to blame operators.
It is to create conditions that allow them to work consistently.

The following training and standardization are needed.

• Standard spray distance
• Standard gun angle
• Standard film thickness
• Application sequence
• Accepted-product samples
• Defect samples
• Film thickness measurement methods
• Risks of overapplication
• Working posture inside the booth
• Post-operation checking methods

Standardizing operator skills improves quality stability and reduces operator burden as well as improving transfer efficiency.

5. Management: Visibility, KPIs, and improvement control

Shop-floor intuition alone is insufficient to improve transfer efficiency.

Paint consumption first needs to be made visible.

Check the following items.

• Daily paint consumption
• Paint consumption per product
• Paint consumption per coated area
• Standard film thickness
• Measured film thickness
• Defect rate
• Rework rate
• Filter replacement frequency
• Booth cleaning time
• Waste-paint quantity
• Consumption differences between operators
• Consumption differences between lines and products

Paint consumption alone does not reveal real improvement.
Considering it together with production volume, coated area, film thickness, defect rate, and waste quantity reveals improvement priorities.

Transfer efficiency is a very useful shop-floor KPI.
It allows material costs, productivity, environmental impact, and operator burden to be considered together.

Issues particularly likely at factories in Vietnam

The following issues are considered likely in coating workplaces in Vietnam.

• Large differences in application technique between operators
• Unclear standard film thickness
• Insufficient film thickness measurement
• Unrecorded spray settings
• No regular checks of booth air velocity
• Fixture shapes that make application difficult
• Product arrangements that increase paint loss
• Paint consumption not linked to production volume
• Hidden costs of waste paint and filter replacement
• Deterioration of the working environment from paint mist left unaddressed

These issues do not arise solely from insufficient effort on the shop floor.
In many cases, the cause is inadequate process design, training, equipment conditions, or management indicators.

This is why CoatureVietnam examines coating processes through 4M + Management.

How to improve transfer efficiency

Transfer efficiency improvement does not have to start with equipment investment.
The first priority is to understand the current situation correctly.

Step 1: Understand current paint consumption

Check paint consumption by product, line, and operator.
Where possible, also check film thickness, defect rate, rework rate, and waste quantity.

Step 2: Check application conditions

Check viscosity, dilution ratio, air pressure, paint delivery rate, spray distance, gun travel speed, and film thickness.
Differences between operators indicate opportunities for standardization.

Step 3: Check the booth and equipment

Check booth air velocity, exhaust balance, filter condition, spray gun wear, and supply equipment condition.
Grounding and fixture electrical continuity are also important for electrostatic coating.

Step 4: Check workpieces and fixtures

Check product shape, hanging arrangements, product spacing, and interference from fixtures.
Difficult-to-coat shapes may cause operators to spray extra paint.

Step 5: Verify improvement using numbers

Compare paint consumption, film thickness, defect rate, cleaning time, and filter replacement frequency before and after improvement.
Quantifying the results makes them easier to communicate to both the shop floor and management.

Transfer efficiency improvement also benefits operators

Transfer efficiency may sound like a cost-improvement indicator.
In practice, it is also closely related to the operator’s working environment.

Paint that disperses without adhering to the product increases mist around operators.
The booth becomes dirty, cleaning increases, and filters require more frequent replacement.
Dirty floors and fixtures also make work more difficult.

Increasing transfer efficiency therefore also reduces the burden on operators.

For CoatureVietnam’s guiding principle, “Coating the Future with Science and Care”, improving transfer efficiency is a very important theme.

Scientifically establishing application conditions reduces paint loss.
This improves the working environment, reduces the cleaning burden, and makes the shop floor safer and easier to work in.
This is our approach to coating improvement.

How CoatureVietnam can help

CoatureVietnam considers coating processes from more than a material-sales perspective.

We examine paint, thinner, application equipment, booths, fixtures, working methods, and quality control together to develop improvements suited to the customer’s shop floor.

Transfer efficiency support can include the following.

• Checking paint consumption
• Organizing application conditions
• Reviewing spray settings
• Improving film thickness control
• Checking paint and thinner compatibility
• Checking booth air velocity and exhaust conditions
• Checking grounding and fixtures for electrostatic coating
• Operator training
• Creating coating SOPs
• Verifying results before and after improvement
• Considering changes in coating method
• Proposing coating equipment and devices

Improving paint costs takes more than price negotiation.
Reviewing the whole process can reveal larger opportunities for improvement.

Summary

When reducing paint costs, paint unit price should not be the only initial consideration.

What matters is how much of the paint used adheres to the product.

Low transfer efficiency burdens cleaning, waste disposal, equipment cleanliness, the working environment, and maintenance costs, as well as paint expenditure.

Improving transfer efficiency requires paint conditions, application conditions, equipment conditions, workpiece shape, operator skills, and management methods to be considered together.

Before buying cheaper paint, there is something to check first.

Is the current coating process using paint without waste?

Coating improvement begins with this question.