logo_2b.gif (2903 bytes)


Seagrave Coatings Corporation 
  For Professional and Industrial Users Only   

    Home Contact Us Search Engine What's New Site Map Related Links
       Seagrave Article

Seagrave Article • Coatings Agenda • New Products

FINISHING TECHNOLOGY
Know Which Finishing Product To Use

Peter Tepperman, Contributing Writer
In the past three years, there has been a flood of imported polyurethane and polyester paints for wood finishing from Europe. While the European products are quite good and have overall improved the acceptance of polyurethanes and polyesters as a substitute for nitrocellulose lacquers and conversion varnishes, there are some risks that need to be evaluated by the finisher. Foreign polyurethane products tend to have more free TDI (toluene diisocyanate) monomer because an aromatic isocycantes is used, which is approximately half the cost of Aliphatic Isocycanates and dries quicker. TDI, however, can cause chronic skin rashes and care must be taken to protect the finisher by using the correct respirator and protective equipment.

It is not the VOC content printed on the label but the VOC of the paint as used that matters.

U.S. manufacturers use mostly aliphatic urethanes that have less than 1/10-percent free TDI, when mixed and therefore dose not have to be listed on the material safety data sheet supplied by the manufacturer. Of course, proper caution still must be taken when spraying and solvent base urethane.

In addition, aromatic isocyanates cause severe yellowing of the film or aging, but aliphatic urethanes cause very little, if any, yellowing. Since Italian manufacturers use many dark wood veneers and high chrome color yellowing is not usually a problem. In the United States, however, styles change often and a white "pickle" finish on kitchen cabinets would not be a suitable use for an aromatic urethane. The finisher must know when to use which coating or suffer the consequences.

Italian imports also are not formulated to the U.S. market. The United States has different state laws regarding VOC emissions and limits on certain types of solvents that can be used. The EPA has passed regulations going into effect at the end of this year for large users of wood finishes that limit the amount of HAPs (hazardous air pollutants) that can be used in their wood finishing operations, and smaller users will need to comply by the end of 1998. To complicate matters, many states have special VOC limits for wood such as metropolitan New York and New Jersey.

Many Italian products do not meet these requirements, especially pigmented finishes because the products need to be reduced by 20 to 30 percent with solvent prior to use to be sprayed. When the products are reduced by this amount of solvent, they do not meet VOC requirements that the state demands and users can be subjected to severe fines.

Remember, it is not the VOC content printed on the label but the VOC of the paint used. Sometimes, Italian systems are not compatible with other coating systems. An example is the polyurethane sealer that is popular because of fast curing, easy sanding and filling properties.

To achieve improved sanding, more sanding aid in the form of Zinc Sterate is used, which is acceptable if the top coat is polyester or polyurethane. Italian manufacturers do not use acid catalyzed lacquers or acid cure varnishes. If an acid cure top coat is put on top of this sealer, a chemical reaction takes place between the zinc and acid causing catalysis or "blooming", and a haze forms in the coating after the paint is fully cured. This haze may not appear for weeks or even months and can cause many problems for the manufacturers. Since acid cure pre-catalyzed and post catalyzed systems are in common use in the United States, it is important to test different systems before they are used, particularly if two manufacturers of paint are involved.

As a knowledgeable purchaser, you can be subject to price increases not due to inflation but currency valuations.

Italian suppliers formulate their products to be used in a mild climate like that which exists in the majority of Italy. In the cold climate of the Northeast and Midwestern states, urethanes may not cure fast enough and polyester won’t cure at all and may need hotter catalysts, whereas in the tropical climate of Florida, these same coatings dry too fast and need slower, retarder solvents to avoid dry spray and orange peel. Although customized finishes cost more, what good is a coating that only works some of the time on your factory floor or needs expensive engineering controls for controlling temperature and humidity! One of the reasons for the success of Italian imports of polyester and polyurethanes is they are usually less expensive than their U.S. counterparts. In the past two years, the dollar has strengthened against the lira by 25 percent. Currencies fluctuate, however, and prices will go up when the U.S. economy slows down and the European economy and the European economy heats up. As a knowledgeable purchaser, you can be subject to price increases not due to inflation but currency valuations.

Peter Tepperman is the CEO of Seagrave Coatings Corporation.

 

Home Up Next
Copyright © 1998 - 2002 by Seagrave Coatings Corporation, Email Seagrave Coatings
Last modified: December 06, 2002 Telephone: (201) 933-1000  Fax: (201) 933-3646. Site built by Techno Works