Coating and Solvent Activities That Typically Need a Permit

Almost every spray booth in California needs an air permit. Most coating lines do too. The bar is low because VOC and toxic air contaminant content adds up quickly.

Use this checklist as a starting point. If you do any of the following, plan on confirming permit status with your air district:

• Paint or coating spray booths (any size, in most districts)
• Powder coating booths (often permitted; some districts exempt cold-application only)
• Roll, dip, flow, electrostatic, or curtain coating lines
• Printing operations using solvent-based inks (flexographic, gravure, lithographic, screen)
• Adhesive and glue application using solvent-based products
• Surface preparation: solvent wipe-cleaning, vapor degreasing, cold-cleaning tanks
• Curing or drying ovens dedicated to coated parts
• Touch-up paint operations using more than a few aerosol cans per shift
• Architectural or industrial maintenance coatings applied at the facility

For metal finishing operations that involve plating tanks, chrome electroplating, or anodizing, see our air permits for metal finishing and plating operations guide. The rules overlap with coating but have their own form set.

The Solvent Thresholds That Catch Facilities Off Guard

One commonly missed trigger is the BAAQMD wipe-cleaning exemption. In the Bay Area, BAAQMD Regulation 2, Rule 1 exempts wipe-cleaning operations only when net solvent use stays under 20 gallons per year (or uncontrolled VOC emissions stay under 150 pounds per year) across all wipe-cleaning at the facility. That figure is specific to wipe cleaning; it is not a universal spray-booth or coating threshold. Cross it, and even a workbench bottle of isopropyl alcohol used for wiping can pull that activity into permitting.

A few things to watch:

• Acetone is exempt as a VOC in most districts (a 1996 EPA decision adopted statewide). If you switched from methyl ethyl ketone (MEK) to acetone, that may have moved you below the threshold.
• Aerosol cans held in the hand are usually exempt; bulk solvent dispensing is not.
• Multiple small operations add up. A facility with one spray gun, one wipe station, and one glue line often clears 20 gallons of VOC per year without anyone noticing.
• The threshold is per year, per facility. Not per booth, not per shift.

In South Coast (SCAQMD), surface coating operations are governed primarily by Rule 1107 (Coating of Metal Parts and Products) and related rules, with solvent cleaning covered under Rule 1171. Each rule sets VOC content limits on the coatings themselves, recordkeeping requirements, and what equipment counts as a permitted source. The thresholds and exemptions differ from BAAQMD’s, which is why a facility moving from Hayward to Long Beach can find itself in a different permitting world overnight.

What Goes Into a Surface Coating Permit Application

The permit packet for a coating operation is substantial. A BAAQMD application uses Form P-101B plus the source-specific Surface Coating form and, where relevant, the Solvent Cleaning form. SCAQMD applications use Form 400-CEQA, Form 400-PS, and the per-equipment Form 400-A and 400-E series.

In both districts, the air district wants the same underlying information from you:

• A description of the booth or line (manufacturer, model, year, capacity)
• The booth’s exhaust configuration: air flow in cubic feet per minute (CFM), stack diameter, and vent height
• Filter media specifications for paint arrestance (particulate control)
• Any abatement device on the booth (carbon adsorption, thermal oxidizer, regenerative thermal oxidizer)
• The coatings and solvents used: Safety Data Sheets (SDSs) for every product, VOC content, hazardous air pollutant (HAP) content
• Annual coating and solvent usage (gallons per year by product)
• Hours of operation
• A facility map showing the booth’s location and its distance to the property line
• A separate map showing the distance to the nearest school (triggers public notification in some cases)

A typical mistake we see when a client tries to assemble this themselves: they list current usage on the form. The annual usage you list becomes the cap your permit allows. If you list current usage and then grow 30%, you are out of compliance with your own permit and need to file a modification before you can run the higher volume. We list a defensible maximum, document the calculation, and protect the client’s headroom.

For the full ATC-to-PTO process across any source type, see our guide on how to get an air quality permit in California.

Spray Booth Specifics the District Will Ask About

When we walk a facility with a spray booth, the first thing we check is the filter bank. Inspectors do the same. Three booth-specific items come up almost every time:

For larger operations or coatings with high HAP content, the district may require a thermal oxidizer or carbon adsorption unit. Those are themselves permitted sources, with their own efficiency records and source testing obligations.

After the Permit: Recordkeeping and Annual Reporting

Getting the Permit to Operate is not the end. Coating operations carry some of the heavier recordkeeping in air permitting because every gallon of paint and solvent that goes through the booth is an emissions number.

What we typically keep on file for a coating permit:

• Monthly coating and solvent usage logs (gallons by product, VOC pounds calculated)
• SDS file kept current as products change
• Filter change log and differential pressure readings
• Annual maintenance records on any abatement device
• Source test reports if the district required one at startup

These records also feed the Annual Emissions Report. Most permitted coating facilities receive a notification from their district each year requiring an AER filing. The data covers January through December, and the deadline is set by each district (SCAQMD’s Data Year 2025 reports are due May 1, 2026; confirm yours). For details, see our piece on Annual Emissions Report California requirements and deadlines.

Common Surprises We Find on Walkthroughs

A few patterns show up often enough that they are worth flagging:

• The “we use VOCs but we’re below threshold” facility. When we walk the site and add up the isopropyl alcohol (IPA) wipe-cleaning, the spray booth coatings, and the occasional epoxy glue line, the facility is well past the point where those activities need permits. They have been operating unpermitted, sometimes for years.
• The inherited spray booth. New ownership, new lease, or a new EHS manager finds a booth in the back of the building and assumes it must be permitted. It often is not.
• The “we switched to water-based” facility. The coatings are water-based, but the cleanup solvent is not. The booth still needs a permit.
• Permits that don’t match what’s running. The PTO covers booth A, but the new booth B was installed without a modification. Both run on the same compressor and stack.

If any of those sound familiar, see operating without an air permit and how to get back into compliance for the path forward.

Next Steps

Whether you are planning a new booth, inherited equipment with unclear permit status, or trying to clean up an existing permit before your next AER, the work starts the same way: identify every source, pull SDSs, run usage numbers against the right district’s rules, and produce a defensible application or applicability letter.