James D Harrell

US Patent:

53208722, Jun 14, 1994

Filed:

Jan 4, 1993

Appl. No.:

8/000558

Inventors:

Thomas E. McNeel - Memphis TN
James A. Harrell - Germantown TN

Assignee:

Buckman Laboratories International, Inc. - Memphis TN

International Classification:

B05D 302

US Classification:

427393

Abstract:

Discoloration of surfaces, such as painted or treated wood surfaces, by tannin-staining caused by the complexing of certain transition metal ions with tannate ions (the process is often referred to in the art as "tannin-stain bleed") is reduced or prevented by contacting a transition metal ion on a painted surface or surface to be painted with a complexing agent for the transition metal ion, such as by the addition of the complexing agent for the transition-metal ion to paint formulations or by pretreatment of the wood surface with the complexing agent before painting. It is believed that the complexing agents form coordination complexes with transition-metal ions on the surface of and within the paint film, thus preventing the formation of highly-colored complexes of the transition metal ions with the tannate ions derived from the tannins in the wood. This technique is applicable to all woods and other surfaces susceptible to tannin-staining and especially to stain-susceptible woods such as redwood and cedar. Using appropriate formulation or application techniques, the method may be used with water-based or solvent-based paints.