Payback period: 1

year Payback period: 2

years

Payback

period: 13 months

Payback

Process

Application

of finish and pre-finish coatings (continued)

Equipment

cleaning

V.B.

Source: Pollution Prevention Options in Wood Furniture Manufacturing, 1992.

Pollution Prevention Case Studies

Payback
Period

Information

not available

Information not available

Henredon Furniture Industries, located in California, applies stains and other finishes to chairs, benches, and a variety of other furniture items. Because the conventional spray guns that Henredon had been using were not meeting current regulations for VOC emissions, the company researched the feasibility of highvolume low-pressure (HVLP) spray guns.

Henredon tested guns by a variety of manufacturers to find those that best fit their needs. The HVLP guns ultimately selected operate on air pressures from 7 to 10 psi, which is within the definitions set by California's South Coast Air Quality Management District. The lower pressure results in less overspray and more efficient use of material.

The new HVLPs increased efficiency such that average material usage was reduced by 13 to 15 percent. Employee training on application techniques was also conducted to improve efficiency. The new guns improved product quality without slowing production rates. Henredon is currently using the HVLP guns to apply lacquers, sealers, and stains at three plant locations.

Henredon saves approximately 18,512 gallons of raw material annually by using the more efficient guns. These savings equate to a reduction in VOC emissions of 126,060 pounds per year.

Purchase and installation cost between $350 and $500 per gun. Henredon figures to save approximately $119,673 per year in raw material usage, for an average payback period of 3.5 months.

Thomson Crown Wood Products, Inc., manufactures wood television cabinets. Parts of these cabinets were sprayed with finishing materials by an air-assisted airless spray gun, resulting in the production of VOCs and a large paint waste stream. To ameliorate this problem, Crown Wood proposed to test highvolume low-pressure (HVLP) spray guns and evaluate their success in reducing these waste streams.

Through in-house, on-line production testing, Crown Wood reviewed four different HVLP spray guns using penetrating stain (no-wipe), glaze, sap stain, equalizer, toner, shade, and water-based black paint. An HVLP spray gun manufactured by one company gave excellent performance during the penetrating stain and regular glaze applications. This gun was also highly recommended by the sprayers for its size, weight, triggering, and cleaning ease. However, because the sprayer did not hold a specific spray pattern very well, it could not be used for heavier finishes. Instead, an HVLP spray gun manufactured by another manufacturer, which also received good ratings by the sprayers, gave much more consistent coverage and spray pattern for the water-based black, sap stain, equalizer, shade, and toner finishes.

With the new HVLP spray guns, Crown Wood has experienced material reductions of 65 percent for equalizer, 65 percent for stain, 54 percent for toner, 35 percent for glaze, 35 percent for no-wipe, and 53 percent for water-based black finishes. These reductions total over 13,300 gallons per year, which also results in reductions in VOCs and paint waste.

A total of $137,448 per year is the estimated savings from purchasing the new spray guns. Costs associated with paint waste reduction have not been determined, but a reduction in the amount of clean-up waste was evident. The cost of the project was $21,350.

In July 1992, Crown Wood altered its printing process room to incorporate the lay-down or roll-on finishing top and end panels of the outside cabinet. With this process modification, 60 percent of the spraying operation is now diverted to the printing room. Along with paint waste and VOC discharges, this new application procedure reduced finishing purchases by 50 percent.

Ethan Allen, Inc., manufactures dining and bedroom furniture. Coating procedures in the finishing operations produced approximately 37,000 pounds of hazardous waste annually. To reduce the quantity and disposal cost of this waste, the company made the equipment substitutions and cleanup changes discussed

below.

Some of the modifications resulted directly from employee suggestions. The company implemented a cost reduction program to facilitate employee involvement in waste/cost reduction activities. Employees submit waste/cost reduction ideas, which are evaluated by a cost reduction committee, and valid suggestions are assigned for savings calculations.

Three main components of the coating operation generate the hazardous waste: overspraying collection systems, material transport systems, and equipment cleanup procedures.

Overspray Collection Systems

•

•

Metal filters replaced paper/cardboard filters for all the coating operations. The metal filters are cleaned in a tank in which solvent is circulated with a diaphragm pump. The waste solvent/coating mix is distilled, and only the overspray is drummed for disposal. The cleaning solvent is reused. The metal filters used for lacquer and sealer overspray are hand wiped, and the dust is sent-off site for recycling.

A fabricated, sloped polyethylene-lined trough replaced absorbent wood shavings used to catch overspray. In the wiping stain booths, the trough is squeezed into a pan, and only the liquid overspray is drummed for disposal.

High-volume, low-pressure (HVLP) spray guns replaced conventional air-assisted spray gun equipment. As a result, the quantity of overspray to be filtered is reduced, and spraying efficiency is increased. Also, each operator is required to attend an annual technical training session. Training is provided by a representative of the spray gun manufacturer.

Material Transport Systems

•

Polyethylene covers replaced cardboard covers for pallets used to transport products through coating operations. The overspray is peeled off the polyethylene cover and drummed for disposal.