When repainting a part,prior to application of the new paint coat the old,paint often must be removed. The waste reduction assessment should start by examining what causes the need for repainting: inadequate initial part preparation; defects in coating application; equipment problems; or coating damage due to improper handling.
While no process is perfect, reducing the need for repainting has a direct effect on the volume of waste generated from paint removal. Once the need for paint stripping has been reduced to a minimum, alternate paint stripping approaches can be considered.
Paint-stripping technologies that are alternatives to chemicals include: abrasive blasting with a variety of materials; mechanical removal using scrapers, wire brushes and sand paper; pyrolysis (vaporization of the paint coating in a furnace or molten salt bath); cryogenics (“freezing” the paint off); and extremely high-pressure water or air.
Key concerns are the type and volume of waste produced. Chemical stripping commonly has been used in a number of applications, but alternate methods that are less toxic and less costly are available. For example, a barrel reconditioning operation was able to replace chemical stripping with mechanical stripping using metal and nylon brushes.
Key factors that must be considered when selecting a paint-stripping method include: potential for cross-media transfer; the characteristics of the substrate to be stripped; the type of paint to be removed; and the volume and type of waste produced. Waste type and volume can have a major impact on cost-benefits associated with a change. Often, a combination of removed paint and chemical stripper requires disposal as hazardous waste.
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