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Pennsylvania House scores a finishing first.



After more than a year of testing, Pennsylvania House begins full-scale production using a revolutionary new spray finishing system designed to apply high solids coatings with fewer VOCs. Editor's note: WOOD & WOOD PRODUCTS published a report in July 1991 regarding chair production at Pennsylvania House's White Deer facility. The article briefly noted that Pennsylvania House was experimenting with the Unicarb Finishing System developed by Union Carbide Chemicals and Plastics Co. Inc. The system represents a new technological alternative for reducing the emission of volatile organic compounds in spray finishing operations. (See page 56.)

Simultaneous to publishing the report, Pennsylvania House began using the Unicarb System full time for lacquer topcoats on chairs. According to Union Carbide officials, Pennsylvania House is the first manufacturer in any industry to market a product that was in part finished with the Unicarb System. Somewhere someone is sitting in the first chair ever sold featuring a lacquer topcoat that was applied with the Unicarb System, a new spray technology which substitutes supercritical carbon dioxide for VOC-containing solvents.

The result is a chair that essentially looks like others in its family made by Pennsylvania House that were finished with air-assisted airless spray equipment. The rub is that volatile organic compound emissions, high on the hit list of air pollution-generating substances covered by the federal Clean Air Act, were reduced by more than half in the application of lacquer topcoats using the Unicarb System.

The chair was manufactured, assembled and finished at Pennsylvania House's plant in White Deer, Pa. It represents the first product ever sold of any kind that was in part finished using the Unicarb System. Though Pennsylvania House can take pride in being acknowledged as the first company to take Unicarb past the test phase, there has been little time for high fives. There is still much to be learned about using this new technology, a fact that all of those involved in the project freely admit.

A finishing start-up

Pennsylvania House was included on a short list of prominent wood furniture companies approached by Union Carbide to test the Unicarb System. The company was also among the quickest to accept Union Carbide's challenge.

"We were looking for furniture companies with good public images and a desire to lead the industry," said Jim Batt, national licensing manager of the Unicarb System for Union Carbide. "Of all the furniture companies that we contacted, Pennsylvania House saw the most immediate possibility of benefit."

By early spring of 1990, after Pennsylvania House and Union Carbide had struck an experimental licensing agreement, Pennsylvania House began its first tests of the Unicarb System. The project incorporates spray equipment developed by Nordson Corp. and lacquers specially formulated by Guardsman Product Inc. for the Unicarb process.

The equipment that Nordson manufactured per a licensing agreement with Union Carbide mixes the finish with supercritical carbon dioxide and conditions it to the right temperature and pressure for delivery to the spray gun. "The equipment being used by Pennsylvania House represents our third generation of Unicarb equipment," said Kenneth Coeling of Nordson. "The system's temperatures and pressures are in the airless range but the characteristics of the spray pattern atomization are more like air spray equipment," he added.

Larry Quist, chief chemist for Guardsman, said the lacquer formulated for use with the Unicarb System has a much higher viscosity than conventional lacquers. The Unicarb formulation contains about 40 percent solids compared to about 22 percent with conventional nitrocellulose lacquers, according to Quist.

"You couldn't use the Unicarb finish with conventional equipment because the viscosity would be too heavy." He further explained why supercritical carbon dioxide is mixed with the formulation. "The carbon dioxide is compatible with nitrocellulose and acts as a diluent to reduce viscosity in the finish. When spray atomization occurs, the carbon dioxide immediately evaporates."

George Palmer, project coordinator of Unicarb research at Pennsylvania House, compared the viscosity of the Unicarb finishing material to honey. "It is extremely thick before it is thinned by the carbon dioxide."

Scaling the learning curve

Pennsylvania House crawled before walking and walked before running in learning the nuances of the Unicarb System.

"We started out testing very slowly, just spraying wood panels, something nice and easy," Palmer said. "Then we put the panels on our cart conveyor to test drying properties. The panels looked good early on."

In the course of the next few weeks, Palmer said tests were performed on a variety of assembled furniture pieces including wicker chairs, chairs made of oak or cherry, dining tables, mirrors and wall units. The chairs and vertical products, mirrors and wall units, "looked good" in the initial tests, according to Palmer.

"We proved very quickly that we could get quality finishes on chairs and vertical surfaces," Palmer said. "However, we experienced solvent trapping on horizontal surfaces, particularly tables. We observed very small bubbles in the surface of the finish that we did not see until they were hand rubbed. We wrestled with the problem for a while and although we were making progress, we decided to stop the table tests for now and proceed full speed ahead with the chair tests."

In spite of the immediate successes, Palmer said Pennsylvania House encountered numerous bumps during the trial period. Yet, he added, "Working with a new technology, we've had a number of glitches along the way, but nearly every one of them up to now has been addressed."

A primary example of a problem that has been addressed concerned the spray gun tip design. "We had some trouble being able to spray fast enough; the tips were producing a spray pattern that was heavy in the center," Palmer said.

Coeling said Nordson went back to the drawing board and worked on developing a spray tip design that would overcome the problem which created an uneven finish. "We've been working on the equipment for close to three years now and have gone through many stages of evolution. Every time we test, we learn a lot more," he said.

Another challenge has been the learning curve required by Pennsylvania House technicians to become familiar enough with the system to feel comfortable with its operation. "The high-tech appearance of the system can be intimidating," said Palmer. "It's not like conventional equipment where you have a simple pump in a drum and a simple trigger on the spray gun. We've had to teach the material handler how to control temperature and pressure of carbon dioxide, how to start up the system and how to shut it down."

Palmer added that the system has been "vulnerable to interruptions." "We have to beware of electricity outages because they can cause pressure drops, and of voltage surges because they can fry out the software system. You don't have to worry about these kinds of things with conventional equipment."


In late July, Pennsylvania House moved the Unicarb System from its research and development lab to its overhead conveyorized chair finishing line. The system then began the critical acid test to see how it would perform on a daily eight-hour production basis. The initial results were encouraging.

"We've had equivalent quality and integrity to our air-assisted airless and have required only about half as many gallons of finish because of greatly increased mile-age we get with the Unicarb finishes," Palmer said. "We accurately meter the number of ounces used per chair by both Unicarb and our air-assisted airless finishing systems. Based on those readings, we calculate that we have reduced VOCs by approximately 70 percent in lacquer spraying chairs with the Unicarb System. We've had a lot of interest from our local Environmental Resources Department.

"The system is still a little slower because we are still getting a handle on it," Palmer added. "But we had the patience to stay with it because the promise was so good."

PHOTO : The Nordson spray gun used with the Unicarb System at Pennsylvania House has a specially designed tip.

PHOTO : Two examples of Pennsylvania House dining chairs that sport lacquer topcoats applied with the Unicarb System.

PHOTO : Pennsylvania House moved the Unicarb System to the chair finishing line after more than a year of laboratory testing.
COPYRIGHT 1991 Vance Publishing Corp.
No portion of this article can be reproduced without the express written permission from the copyright holder.
Copyright 1991, Gale Group. All rights reserved. Gale Group is a Thomson Corporation Company.

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Title Annotation:new spray finishing system with fewer volatile organic compounds emission
Author:Christianson, Rich
Publication:Wood & Wood Products
Date:Oct 1, 1991
Previous Article:The metamorphosis of M & J Woodcrafts.
Next Article:A new pollution prevention technology.

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