When a liquid coating is sprayed, part of the material remains on the product, part becomes overspray, and volatile ingredients may evaporate into the booth exhaust.

The exhaust filters capture coating droplets and solid particles. Most standard paint-arrestor filters do not remove solvent vapors or volatile organic compounds from the exhaust air.

That means a finishing operation may need records showing:

• Which coatings and solvents were used
• How much material was used
• How the materials were mixed
• The VOC content of each material
• The hazardous air pollutant content
• How emissions were calculated
• Whether permit or regulatory limits were met

Good recordkeeping is more than collecting Safety Data Sheets in a binder. The records must connect purchased materials, actual usage, product composition, calculations, emissions, and compliance decisions.

If the facility cannot reconstruct the calculation, it may not be able to prove compliance.

What Is a VOC?

VOC stands for volatile organic compound. VOCs include many carbon-containing compounds that participate in atmospheric photochemical reactions.

In finishing operations, VOCs may be found in:

• Coatings
• Primers
• Sealers
• Clearcoats
• Reducers and thinners
• Cleaning solvents
• Stripping materials
• Adhesives
• Sealants
• Touch-up products

Not every volatile organic ingredient is treated as a regulated VOC for every air-quality calculation. EPA excludes certain compounds from its regulatory VOC definition because they have been determined to have negligible photochemical reactivity.

State and local requirements may differ. Always use the VOC definition and calculation method required by the applicable permit or regulation.

What Is a HAP?

HAP stands for hazardous air pollutant. HAPs are pollutants listed under Section 112 of the Clean Air Act because they may cause serious health effects or adverse environmental effects.

Coating-related HAPs may include certain:

• Solvents
• Metal compounds
• Isocyanate compounds
• Pigments
• Curing agents
• Cleaning chemicals

A material can contain both VOCs and HAPs. However, VOC and HAP are not interchangeable terms.

A compound may be:

• A VOC but not a listed HAP
• A listed HAP but excluded from a particular VOC definition
• Both a VOC and a HAP
• Neither for the applicable calculation

VOC and HAP totals should therefore be calculated separately.

Start With the Applicable Requirements

There is no single recordkeeping system that fits every finishing operation.

Requirements may come from:

• A facility air permit
• A permit-by-rule or general permit
• A state implementation plan
• A federal New Source Performance Standard
• A National Emission Standard for Hazardous Air Pollutants
• A state or local coating rule
• A facility-wide emission limit
• A coating-category VOC limit
• A customer or corporate environmental program

Before designing a spreadsheet or log, identify:

• Which operations are covered
• Which materials must be tracked
• Whether compliance is based on material content, usage, or emissions
• Whether calculations are required daily, monthly, or annually
• Whether a rolling 12-month total is required
• Which emission factors and equations must be used
• Which records must be retained
• How long the records must be kept
• Which reports or certifications must be submitted

The permit and applicable regulations—not a generic spreadsheet—control the calculation.

Build a Controlled Material List

Create a master list of every coating-related material that enters the finishing process.

Include:

• Product name
• Manufacturer
• Product or part number
• Material category
• Coating color or formulation when relevant
• Container size
• Density
• VOC content
• Total HAP content
• Individual HAP content when required
• Water content
• Exempt-compound content
• Solids content
• Approved mixing ratio
• Source of the composition data
• Revision date of the supporting document

Do not identify a material only as “blue paint” or “shop thinner.” Use the manufacturer’s exact product identification.

The Safety Data Sheet May Not Be Enough

A Safety Data Sheet is essential for hazard communication, but it is not always designed to provide the exact composition data needed for an air-emission calculation.

An SDS may:

• List ingredients as concentration ranges
• Omit nonhazardous ingredients
• Use trade-secret designations
• Report regulatory VOC values differently from the permit
• Provide insufficient information for individual HAP calculations

Additional information may be needed from:

• The technical data sheet
• The product data sheet
• A manufacturer’s VOC certificate
• A HAP-content certification
• A formulation data sheet
• A written statement from the manufacturer
• An approved laboratory analysis

Retain the document used as the basis for each value. Do not copy a number into a spreadsheet without recording where it came from.

Know Which VOC Number You Are Using

A coating document may contain more than one VOC value.

Examples may include:

• VOC by weight
• VOC in pounds per gallon of material
• VOC in grams per liter of material
• VOC less water
• VOC less water and exempt compounds
• VOC as supplied
• VOC as applied

These values are not interchangeable.

A coating rule may limit VOC in the coating less water and exempt compounds, while an emission inventory may require the total pounds of VOC contained in the amount of material used.

Record the units and basis with every VOC value. A number without its units and calculation basis can easily be misused.

Track the Material as Applied

A coating may meet its VOC limit as supplied but exceed the limit after too much reducer is added.

Record:

• Base coating used
• Activator or hardener added
• Reducer or thinner added
• Other additives
• Mixing ratio
• Quantity mixed
• Date or batch period
• Applicable coating category

The calculation must include all components required by the applicable rule or permit.

Do not assume that an activator, reducer, or additive has the same VOC or HAP content as the base coating.

Track Cleaning Solvent

Cleaning material can be a substantial source of VOC and HAP emissions.

Include solvent used for:

• Gun cleaning
• Hose and fluid-line flushing
• Pump cleaning
• Pressure-pot cleaning
• Mixing-room cleanup
• Booth cleaning
• Parts washing
• Wiping and surface preparation
• Color-change operations

Do not count only the solvent purchased for the spray department if employees can obtain cleaning solvent from another storage area.

The recordkeeping system should capture all material used by the regulated operation.

Ways to Measure Material Usage

Material usage may be determined through:

• Container counts
• Purchase records
• Inventory reconciliation
• Mix-room issue logs
• Weight measurements
• Flow meters
• Batch tickets
• Automated mixing-system records
• Production recipes

The selected method should be consistent, documented, and capable of supporting the required calculation.

Inventory Reconciliation

A basic inventory approach may use:

Material Used = Beginning Inventory + Purchases - Ending Inventory - Documented Transfers

The equation may require additional terms for returned materials, off-site shipments, waste, reclaimed solvent, or inventory adjustments.

The method must match the facility’s approved procedure and applicable requirements.

Basic VOC Mass Calculation

When the VOC content is expressed as mass per volume of material, a basic calculation may be:

VOC Used = Material Used × VOC Content

For example:

• Material used: 25 gallons
• VOC content: 3.2 pounds per gallon

25 Gallons × 3.2 Pounds per Gallon = 80 Pounds of VOC

This calculates the amount of VOC contained in the material used. Whether it also represents reportable VOC emissions depends on the applicable rule, control system, capture method, waste handling, and approved calculation procedure.

Basic HAP Mass Calculation

If HAP content is reported as a weight fraction, the basic calculation may be:

HAP Used = Material Used by Weight × HAP Weight Fraction

If 100 pounds of coating contains 8% of a listed HAP:

100 Pounds × 0.08 = 8 Pounds of HAP

If usage is recorded in gallons and HAP content is provided as a weight percentage, the material density may be needed to convert gallons to pounds.

Material Weight = Gallons Used × Pounds per Gallon

Then:

HAP Used = Material Weight × HAP Weight Fraction

Check every conversion carefully. A percentage must be converted to a decimal before multiplication. Eight percent is entered as 0.08—not 8.

Total HAP and Individual HAP

A facility may need to track:

• Total combined HAP emissions
• Each individual HAP
• Specific groups of compounds
• Metal HAPs
• Organic HAPs

Tracking only total HAP may not be enough. A facility could remain below a combined-HAP threshold while exceeding a limit for one individual pollutant.

The material database should preserve individual HAP information whenever the applicable requirement calls for it.

Do Not Confuse Usage With Emissions

Material usage and air emissions are related, but they are not always identical.

An emission calculation may consider:

• VOC or HAP content of the material
• Quantity used
• Amount retained in the finished coating
• Amount collected as waste
• Amount reclaimed or recycled
• Capture efficiency
• Control-device destruction or removal efficiency
• Approved emission factors
• Permit-required assumptions

Many uncontrolled VOC calculations conservatively assume that the volatile content is emitted. A facility should not subtract reclaimed solvent, waste material, or controlled emissions unless the applicable rule or permit allows the subtraction and the facility has the records required to support it.

Transfer Efficiency Is Not VOC-Control Efficiency

A high-transfer-efficiency spray gun places more coating solids on the part and reduces overspray.

However, transfer efficiency should not automatically be treated as VOC-emission-control efficiency.

Volatile ingredients may evaporate from:

• Coating deposited on the part
• Airborne spray
• Overspray captured by filters
• Mixing containers
• Flash-off areas
• Curing ovens
• Cleaning operations

Improving transfer efficiency reduces coating waste, but the facility must use the emission-calculation method required by its permit or regulation.

Exhaust Filters Do Not Normally Remove VOCs

Dry spray-booth filters are designed to capture coating droplets and particles.

They do not normally capture gaseous VOCs or organic HAP vapors. Solvent-laden air passes through the paint-arrestor filters and enters the exhaust system unless a separate air-pollution-control device is installed.

Do not claim a VOC reduction based solely on exhaust-filter efficiency.

Records for Air-Pollution-Control Equipment

If the facility claims emission reduction from a control device, additional records may be required.

Depending on the system, records may include:

• Control-device operating temperature
• Pressure differential
• Airflow
• Capture-system operating parameters
• Carbon-bed replacement or regeneration
• Operating hours
• Downtime
• Malfunctions
• Inspection and maintenance
• Performance-test results
• Corrective actions

The facility must operate and monitor the equipment according to the applicable permit and regulatory requirements.

Monthly and Rolling 12-Month Totals

Many permits require emissions to be calculated for each calendar month and as a rolling 12-month total.

A rolling 12-month total is recalculated every month by adding the newest month and removing the oldest month.

For example, the total for September would include October of the previous year through September of the current year. The October total would then include November of the previous year through October of the current year.

A rolling 12-month total is not the same as a calendar-year total.

Potential Emissions and Actual Emissions

Actual emissions are generally based on what the facility actually used or emitted during a defined period.

Potential emissions consider the facility’s ability to emit pollutants under specified operating assumptions, taking into account only limitations that are legally enforceable when required.

Purchase records alone do not necessarily establish potential emissions. Likewise, potential emissions should not be reduced by informal production plans that are not enforceable.

Because these calculations can determine permitting status, they should be reviewed by a qualified environmental professional.

What Should a Daily or Batch Record Include?

A practical material-use record may include:

• Date
• Work order or production line
• Coating operation
• Product manufacturer
• Product name and number
• Color or formulation
• Base-coating quantity
• Activator quantity
• Reducer quantity
• Cleaning-solvent quantity
• Mixing ratio
• Total material prepared
• Unused material returned
• Waste or reclaimed material
• Employee completing the record

The units must be clear. Do not mix gallons, quarts, liters, pounds, and kilograms without documented conversions.

What Should the Monthly Record Include?

A monthly compliance record may include:

• Beginning and ending inventory
• Purchases and transfers
• Usage by material
• VOC emissions by material
• HAP emissions by material
• Individual HAP totals when required
• Cleaning-material emissions
• Total monthly emissions
• Rolling 12-month emissions
• Applicable limit
• Compliance status
• Calculation version
• Name of the person completing or reviewing the calculation

Keep Supporting Documents Together

The final monthly total should connect to:

• Purchase records
• Inventory records
• Material-issue logs
• Batch and mixing records
• Safety Data Sheets
• Technical data sheets
• Manufacturer VOC certifications
• Manufacturer HAP information
• Density information
• Waste and reclamation records
• Control-device records
• Calculation spreadsheets
• Submitted reports

An auditor should be able to select one monthly total and follow the calculation backward to the original material records.

Control the Spreadsheet

A spreadsheet can calculate accurately and still produce the wrong answer if its formulas, conversion factors, or material data are incorrect.

Protect the calculation by:

• Assigning a version number
• Restricting formula changes
• Identifying input cells
• Locking calculation cells
• Using consistent units
• Displaying the source of each emission factor
• Testing formulas with known examples
• Reviewing updates before release
• Maintaining an audit trail
• Backing up the records

When a coating formulation changes, update the material record only after the revised manufacturer information has been reviewed.

Do not overwrite historical composition data if it was used for earlier calculations. Preserve the version that applied when the material was used.

Watch for Duplicate Counting

A material can be counted twice when information comes from overlapping systems.

Examples include:

• Counting purchases and shop issues as separate usage
• Counting mixed coating and each component again
• Counting returned material as both used and stored
• Counting reclaimed solvent as new solvent usage
• Counting the same operation in two emission units

The written procedure should identify the official source for every quantity.

Watch for Missing Materials

Commonly overlooked materials include:

• Touch-up aerosols
• Maintenance coatings
• Adhesives and sealants
• Gun-cleaning solvent
• Solvent used in parts washers
• Line-flushing material
• Floor and booth-cleaning products
• Coatings brought in for trials
• Small containers stored outside the mixing room
• Materials used by contractors

“If it is only a small amount” is not a recordkeeping method. Small quantities can become significant when used repeatedly.

Record Retention

The required retention period depends on the applicable permit and regulation. Many air rules require records to be retained for several years, but the exact period must be confirmed for the facility.

Records should remain:

• Legible
• Complete
• Accessible
• Protected from unauthorized changes
• Backed up
• Organized by reporting period
• Available for inspection

If electronic records are used, the facility should be able to retrieve and reproduce them throughout the required retention period.

Perform an Internal Recordkeeping Audit

Periodically select one coating and trace it through the entire system:

1. Confirm the exact product identity.
2. Locate the current composition documents.
3. Verify the VOC and HAP values used.
4. Confirm the units and calculation basis.
5. Trace the amount purchased or issued.
6. Verify the usage calculation.
7. Review the monthly VOC calculation.
8. Review the individual and total HAP calculations.
9. Confirm inclusion in the rolling total.
10. Compare the result with the applicable limit.

If the trail breaks, correct the system before an inspector, customer, or permit report exposes the gap.

A Practical VOC and HAP Checklist

Before closing the monthly record, confirm:

• Every regulated coating operation is included.
• Every coating component is included.
• Reducers and activators are included.
• Cleaning materials are included.
• VOC values use the correct basis and units.
• Total and individual HAPs are calculated as required.
• Material densities are current.
• Exempt compounds are handled according to the applicable rule.
• Usage records reconcile with inventory or issue records.
• Waste or reclamation credits are supported and permitted.
• Control-device credits are supported by operating records.
• Monthly and rolling totals are correct.
• The applicable limit is shown.
• Supporting documents are retained.
• The calculation has been independently reviewed.

The Bottom Line

VOC and HAP recordkeeping begins before the coating reaches the spray gun.

It begins with approved products, reliable composition data, controlled mixing, accurate usage records, correct calculations, and retained supporting documents.

Know what entered the finishing process. Know what was added. Know what was used. Know how the emissions were calculated.

Then keep enough evidence to prove it.

The finish may leave the booth today. The record must still tell the story years from now.

This article provides general educational information. VOC and HAP definitions, calculations, reporting requirements, and record-retention periods vary by jurisdiction, permit, source category, and operation. Facilities should consult their air permit, applicable federal and state regulations, and a qualified environmental professional.

Authoritative Resources

• U.S. EPA—What Are Volatile Organic Compounds?
• U.S. EPA—Clean Air Act Hazardous Air Pollutant List
• eCFR Example—Surface-Coating Recordkeeping Requirements

© 2026 Azimuth Spray Systems, LLC. All rights reserved.

Tags: VOC recordkeeping, HAP recordkeeping, coating emissions, air permit compliance, paint usage records, VOC calculations, hazardous air pollutants, cleaning solvent emissions, rolling 12-month total, coating compliance, environmental records