Incentives and Techniques for Pollution Prevention in Furniture Coating Operations

Index

Introduction

The 1990 Clean Air Act Amendments (CAAA) will require many furniture manufacturers to reduce emissions of volatile organic compounds (VOCs) and hazardous air pollutants (HAPs). Generally, new regulatory requirements impose costs, and, for furniture companies, these come at a time when increasing competition demands that costs be reduced.

A combination of approaches will usually be required to achieve compliance with the regulations; one single approach or technology will usually not be adequate to achieve the level of performance required by the Act. Techniques and technologies are available that offer manufacturers not only an opportunity to comply with the regulations and reduce emissions but also to save money and become more efficient. Pollution prevention is one approach to reducing HAP and VOC emissions, and preventing pollution is usually more cost effective than installing control devices. Also, the CAAA include several incentives that encourage companies to reduce air emissions.

This Fact Sheet discusses, first, some of the CAA emission reduction incentives that help offset the economic and regulatory burden of complying with the Act and of which companies can and/or must take advantage. Opportunities for using pollution prevention to reduce emissions and save money are then presented.

Return to this document's index.

Regulatory Incentives for Emissions Reduction

Return to this document's index.

Pollution Prevention Techniques

Many furniture companies will find that pollution prevention techniques used to modify and improve their current processes to be more cost effective than installing emissions control devices on stacks to reduce HAP and VOC emissions. Applicable pollution prevention techniques include improved operation and maintenance, inventory management, water and chemical conservation, production process modification, and recovery and recycle/reuse.

The following sections discuss the application of some of these pollution prevention techniques to reduce air emissions, hazardous waste generation, and worker exposure to toxic chemicals. Case studies are included to demonstrate that these techniques and technologies have been implemented effectively by other companies. It is important to keep in mind that most of the activities in the case studies preceded the passage of the CAAA and that the cost savings alone justified the changes the companies made.

Return to this document's index.

Operation and Maintenance

Proper operation and maintenance of equipment play a critical role in the efficient use of materials. Especially true for furniture coating operations, it has been estimated that 25 to 50 percent of all waste can be attributed to poor operation and maintenance. The following sections overview some tips for good operation and maintenance.

  1. Generally, less viscous coating materials are easier to atomize, and they can be atomized at lower pressures. There are two ways to control viscosity: by dilution with a solvent and by heating. Heating the coating material to the desired viscosity instead of diluting it with solvent can give comparable atomization with lower VOC emission potential.
  2. Air and fluid pressure should be high enough but no higher than needed to provide good atomization yet minimize overspray, blowback, and worker exposure.
  3. The spray pattern should be optimized to the workpiece size, shape, and orientation. Slender pieces should be coated with a narrow pattern while a larger pattern can be used for larger pieces.
  4. The piece to be painted should be positioned to make spraying as comfortable as possible for the operator, and small pieces should be positioned such that overspray from one piece will fall onto another piece.
  1. Depending on the type of spray gun, the gun tip should be held approximately 8 to 12 inches from the workpiece. If it is held too far away, a dry spray and decreased transfer efficiency may result, while the paint may run and sag if the gun is held too close to the piece.
  2. To reduce uneven paint coverage, the operator should hold the gun perpendicular to the workpiece as much as possible. Rather than a pivot of the wrist, which will cause the gun to tilt, a sweeping arm motion will usually keep the gun in the proper position.
  3. Proper triggering, i.e., the gun is triggered with each stroke, reduces material usage and finish defects. The stroke should be started before the trigger is pulled, and the trigger should be released before the end of the stroke.
  4. Training should not be considered a one-time event. Even the best trained operators will fall back into old bad habits over time. Training should be repeated periodically, even as often as once or twice a year, to reinforce proper technique and to ensure that new employees are trained properly.
  1. Spray guns need to be kept clean and lubricated daily to keep them operating properly. The trigger, control valves, and springs should be lubricated periodically according to manufacturers' recommendations.
  2. When the gun is cleaned in solvent, only the tip of the gun, not the entire gun, is immersed; immersion of the entire gun can cause scale to build up in the gun, which can result in problems with finish quality.
  3. The spray pattern should be checked periodically for wear or clogging.
  4. Since worn parts can significantly reduce painting transfer efficiency, they should be replaced as needed.2

Return to this document's index.

Production Process Modifications

Pollution prevention through production process modifications include high-tech changes such as chemical substitution, equipment substitution or modification, and product redesign or reformulation.

  1. Many companies are evaluating materials that contain reduced quantities of solvents as substitutes for materials currently used. Examples include high-solids coatings, low-VOC coatings, and waterborne coatings. Coatings manufacturers have made great strides in developing alternative coatings that provide excellent finish quality. While these substitute materials are very effective in reducing VOC emissions, most of them still contain significant quantities of solvents which are regulated as HAPs. For example, many of the waterborne coatings contain glycol ethers, which are HAPs. Users of high-solids coatings should resist the temptation to thin the coatings by adding solvent. As mentioned, the coatings should instead be thinned by heat to reduce the viscosity.
  2. Some companies have worked with their coatings suppliers to replace HAP solvents with non-HAP solvents in the coating formulation. However, these substitute solvents are VOCs just like the solvents they replaced, and some are regulated by states as toxic air pollutants.
  1. Electrostatic coating of metal parts has been employed effectively for many years, and its use for wood finishing transfer efficiency is becoming more common.
  2. Worker health and environmental concerns and the desire for improved finish quality have prompted growth in the use of powder coatings for metal finishing.

Two other technologies appear to hold great potential for widespread application for wood finishing: high-volume/low-pressure spray equipment and UNICARBTM technology.

  1. High-volume/low-pressure (HVLP) spray equipment, which has been demonstrated and adopted by several North Carolina wood furniture manufacturers, provides transfer efficiency as high as 40 to 65 percent compared to 20 to 40 percent for conventional air spray technology. The results are a wealth of reductions: reduced raw material use and overspray, which lead to reduced solid and hazardous waste and fewer booth cleanups. The lower atomization pressure also results in reduced blowback of the coating material, which reduces worker exposure. HVLP is effective for applying either solvent or waterborne materials.
  2. The UNICARB system uses super-critical carbon dioxide (CO2) in place of some organic solvents to apply coatings to wood, metal, and plastic materials. Unlike the solvents it replaces, CO2 is not a VOC or a HAP. Furniture manufacturers who have evaluated UNICARB technologies in their plants have experienced improved finish quality with fewer coating applications. The technology can easily be dropped into existing coating lines and can apply most existing resins. Specially formulated UNICARB coatings are available from a number of coating suppliers. Currently, Nordson is the sole supplier of UNICARB spray equipment. A system supply unit that can serve two spray operators costs approximately $38,000.5

Return to this document's index.

Recovery and Recycle/Reuse

Recovery and reuse or recycling of materials either on-site, off-site, or through an inter-industry exchange is yet another pollution prevention technique than can reduce waste management costs and raw material purchases. Here are examples of successful recovery and reuse techniques:

  1. Reuse of cleaning solvent for painting lines and equipment as a reducer for the next batch of the same or darker color. Some furniture companies have been successfully reusing cleaning solvent for years.
  2. Distilling "dirty" solvent and reusing it for cleaning is another common practice.
  3. Also, wet spray booth wash water can be recycled following removal of paint solids.
  4. Waste Exchange. Often one company's waste can be used by other companies as raw materials. Such reuse is known as a waste exchange. For example, solvents used in the furniture industry may be suitable for use by other companies. Similarly, waste nitrocellulose lacquer dust is used by some coatings manufacturers as a raw ingredient in nitrocellulose topcoats.

Return to this document's index.

Summary

Pollution prevention offers furniture manufacturers an opportunity to reduce VOC and HAP emissions and save money at the same time. Many companies may be able to come into full compliance with the Clean Air Act Amendments without installing expensive pollution control equipment, which can pay for itself only through avoided environmental fines and other intangible costs such as improved environmental quality and public relations. The case studies presented here show companies that have reduced air emissions and hazardous waste generation with less than a one-year payback through reduced raw material usage. These companies also realized the intangible savings.

Return to this document's index.

Case Studies

Operator Training - Ethan Allen Furniture, Old Fort, North Carolina

Ethan Allen videotaped each spray gun operator as coatings were being applied to typical workpieces. The operators then met in small groups with the supervisor and finishing experts to review the tapes. The operators identified their own poor techniques by viewing the tapes and received constructive advice and hands-on instruction on ways to improve. After another videotaping, the operators compared the before-and-after tapes. The company projected an 8- to 10-percent reduction in coating material usage through improved spray technique. This reduction translated into an estimated savings of $50,000 to $70,000 annually.3

Return to this document's index.

HVLP Spray - Alexvale Furniture, Taylorsville, North Carolina

Alexvale Furniture switched from conventional spray equipment to HVLP equipment for applying finishing materials. The excessive overspray of the conventional equipment resulted in large quantities of hazardous waste from booth cleanout and filter replacement. The HVLP equipment uses less coating materials and reduced hazardous waste generation by 40 drums per year. Cost savings were estimated to be $50,000 per year. The payback period was less than one week.6

Return to this document's index.

UNICARBTM Coating Application

A wood furniture manufacturer conducted an in-plant trial of UNICARB coating technology for applying sealers and topcoats, which were formulated to eliminate HAPs. The UNICARB system resulted in a 50-percent reduction in material usage, and because a thicker coating can be applied with UNICARB, the company was able to eliminate one coating application. Finish quality improved, and fewer reworks were necessary.

This trial was part of an overall coating process modification. The company also switched to HVLP equipment for applying waterborne stains and washcoats. Overall VOC emissions were reduced by 65 percent. The company estimated an annual savings of $125,000 with a payback for the UNICARB equipment of less than a year. The process modifications may allow the company to change its status under the Clean Air Act to a minor HAPs source.

Return to this document's index.

HVLP Spray - Herendon Furniture, Morganton, North Carolina

Herendon Furniture switched from conventional to HVLP spray equipment operating at 7 to 10 psi for applying lacquers, sealers, and stains to wood furniture products. Spray operators received training on proper use of the new equipment. The company realized a 13- to 15-percent reduction in coating usage and savings of $120,000 per year in raw material usage. The new equipment also improved product quality without slowing line speeds. The payback period for the project was 3.5 months. The change also reduced VOC emissions by 126,000 pounds per year.4

Return to this document's index.

Solvent Segregation and Reuse - Sherwin-Williams, Greensboro, North Carolina

Sherwin-Williams, formerly DeSota, Inc., manufactures industrial coating materials. Waste from batch cleanup is separated by color and is then used when the next batch of that color is made. This practice has reduced waste mineral spirits at the company by 98 percent from 25,000 pounds to 400 pounds per year. Virgin mineral spirits purchases and paint raw materials have also been reduced.2

Return to this document's index.

Case Study: Wet Spray Booth Wash Water Recycling - Thomson Crown Wood Products, Mocksville, North Carolina

In the past, Thomson Crown Wood Products disposed its contaminated wet spray booth wash water as hazardous waste. The company instituted a system to separate the paint solids from the waste water and then recycle the water back to the spray booth. The idea for this project came from a Quality Leadership Program team of employees. The change reduced hazardous waste disposal costs by $92,500 per year. The company was the 1991 recipient of the Governor's Award for Excellence in Hazardous Waste Management.6

Return to this document's index.


Pollution prevention has been proven by many, many companies to be the most cost-effective approach to environmental protection. The Industrial Pollution Prevention Program of the NC Office of Waste Reduction is available to help companies identify opportunities for pollution prevention. Companies interested in receiving free, non-regulatory technical assistance and education on methods to eliminate, reduce, or recycle wastes before they become pollutants or require disposal should call the Office of Waste Reduction at (919) 715-6500 or e-mail nowaste.owr.ehnr.state.nc.us.

References

  1. U.S. Environmental Protection Agency. "The Clean Air Act Amendments of 1990: A Guide for Small Businesses." EPA Report No. 450-K-92-001. September 1992.
  2. "Air Spray Basics." Graco, Inc.
  3. North Carolina Pollution Prevention Pays Program. Accomplishments of North Carolina Industries: Case Summaries. January 1987.
  4. North Carolina Pollution Prevention Pays Program. Unpublished Case Study. 1992.
  5. Personal Communication. John Kost. National Sales Manager, Nordson Corporation. September 14, 1992.
  6. Governor's Award for Excellence in Waste Management. 1991.
  7. Personal Communication. Furniture Manufacturer. September 14, 1992.
Presented at The Furniture Industry and the Environment Conference, Hickory, North Carolina, November 18, 1992, by David Williams, Manager, Industrial Pollution Prevention Program, NC Office of Waste Reduction.

Return to this document's index.

OWR. May 1993.