Table of Contents
Powder Coatings: Regulatory Requirements
The Clean Air Act regulates the emission
of particulate matter of various
sizes (40 CFR Part 50). Small dry powder
particles can be suspended in exhaust air streams in amounts that would
subject an operator to Title V
permitting requirements. One common control technology for capturing
particulate matter is a dry filter to capture the particles. These
technologies are typically used in conjunction with the application method
chosen for a facility. Due to the very low solvent content of powder
coating materials, regulations concerning volatile
organic compounds (VOCs) or hazardous
air pollutants (HAPs) are typically not a concern. However, if
large quantities of the material are used, then these air emissions may
cause a problem. VOCs or HAPs should be monitored during curing stages
when the materials would be released.
As part of the Clean Water Act, Effluent
Guidelines and Standards for Metal Finishing (40 CFR Part 433) have
been established that limit concentrations of heavy
metals, toxic organics, and
such as suspended solids, in
wastewater streams. Powder coating particles may be classified as
suspended solids if found in a large quantity. These materials can
enter the wastewater when cleaning powder coatings from containers, equipment
or spills. Actual limits for effluent constituents are dependent
on the size of the operation and the amount of wastewater generated from
the facility. If the facility discharges directly to receiving
waters, these limits will be established through the facility's National
Pollutant Discharge Elimination System (NPDES) permit (40
CFR Part 122). Facilities which are indirect dischargers releasing
to a POTW
must meet limits in the POTW's discharge agreement. Wastewater streams
with concentrations exceeding permit limits will require pretreatment
prior to discharge to receiving waters
or to a publicly
owned treatment works. Pretreatment may include separation of
liquid wastes to remove solvents, and settling or precipitation of solid
Solid and Hazardous Waste
Under the Resource Conservation and Recovery
Act (RCRA), organic finishing facilities are required to manage listed
and characteristic hazardous wastes (40 CFR
Part 261). Powder coatings may contain constituents listed or
characterized as hazardous wastes. Residual powder coating materials,
their containers, and contaminated materials (such as rags, masking material,
coveralls, and filters, etc.) may require treatment as a hazardous waste
depending on their formulation. Hazardous waste management (40
CFR Part 262) includes obtaining permits for the facility in order
to generate wastes, meeting accumulation limits for waste storage areas,
and manifesting waste containers for off-site disposal. Responsibilities
will vary according to the amount of hazardous waste material generated;
facilities generating at least 100 kilograms of hazardous waste per month
must comply with the hazardous waste generator requirements of
40 CFR Part 262.
Each state and/or region is primarily responsible for the regulation
of non-hazardous solid wastes (those not governed by the hazardous waste
provisions of RCRA). Check with state environmental agencies for
specific information or guidance.
Do powder coatings come in contact with exhaust air streams? If so,
do concentrations of particulate matter exceed the limits established by
facility air permits?
Do powder coatings come in contact with water streams? If so, do
concentrations of pollutants exceed limits established by the facility
NPDES permit or POTW discharge agreement?
Are all powder coatings and powder coating wastes properly labeled and
packaged in accordance with 40 CFR Part 262, Subpart C?
Are wastes contaminated with powder coatings classified as hazardous? If so, are the wastes handled and manifested in accordance with 40 CFR
Part 262, Subpart B? Are hazardous wastes segregated from non-hazardous
Powder Coating Material: Common Causes of Violation
- Powder coatings are small, dry particles that may be suspended in
air currents at levels exceeding concentrations for dust and respirable
particulates established by Title V permits.
Powder coatings contain some amount of solvents classified as volatile
organic compounds that can volatize. Most powder coatings have a
very low VOC content; but when large volumes of the material are used,
the ambient level of the volatile organic compounds may be an issue.
Containers with small amounts of powder coatings may be considered hazardous
solid waste that must be stored, manifested and disposed according to the
RCRA standards at 40 CFR Part 262.
Powder Coating Material: Sources of Pollution
- Powder coating materials can create a fine dust if handled in open
containers exposed to air currents.
Powder coatings contain some amount of materials classified as volatile
organic compounds and hazardous air pollutants.
Powder coatings may spill due to improper handling or holes in containers. The dry material may become contaminated with dust, dirt, other types of
powder coating materials, or other undesirable solid particles prohibiting
Powder coatings may be stored improperly and no longer meet quality standards,
thus becoming waste. In addition, coatings that are not used up completely
in a job and have no use in another job are considered waste.
Powder coatings come in containers that become solid waste once empty or
when the coating is no longer useable or needed. Containers can range
from small bags with a few ounces of powder to large bags or barrels. Residual coating material left inside the container adds to the volume
of solid waste.
Powder coatings require heated curing cycles unlike liquid coatings that
may be air dried in some cases. This may increase energy consumption
for curing processes.
Powder Coating Material: Pollution Prevention Alternatives
In comparison with traditional solvent-based coatings, powder coatings
are a pollution prevention alternative in and of themselves. The
volatile organic compound content is much lower than for solvent-based
coatings. In addition, the higher solids content of powder coatings
results in a lower volume of material needed for a given surface area.
Proper scheduling and procurement can reduce the amount of residual coating
material waste. To reduce residual coatings, buy only as much material
as needed to complete job. Mix remaining light colored coatings into
darker colored coatings where possible. Purchase coating materials
in the largest containers possible for the volume; since the surface area
to volume ratio of the container is lower, less material is left on the
inside of the containers to be thrown away. Work with coating vendors
to have larger containers returned for refilling. Rotate stock of
coatings to use older material first (first in - first out practice). Before discarding an expired coating, test to see if it would still meet
quality requirements. Donate or sell old and unwanted coating materials
as raw material to others or see if vendor will take it back.
Restrict traffic in storage areas to reduce spills and accidents. Keep storage and work areas clean so spills are more noticeable and reaction
time for cleanup is reduced. Control the temperature in storage areas
to prevent the freezing and heating of coating materials that will spoil
Enclose or cover containers of coating material when not in use. Closed containers reduce contamination from facility dust and dirt. Closed containers also minimize exposure to water and water vapors that
are readily absorbed by the powder materials. Wet powder coatings
form large clumps that will not perform properly in application equipment.
Train employees on safe handling of materials and wastes and encourage
continuous improvement. Training familiarizes workers with their
responsibilities, which reduces spills and accidents.