Effect of water repellent preservatives and other wood treatments on restoration and durability of millwork

This report describes the long-term performance of painted window units that were placed outdoors near Madison, Wisconsin, in 1956. Covered in this report are the effects of the initial water repellent preservative (WRP) treatment during the first 6 years of exposure, a comparison of the water repellent effectiveness (WRE) ofthe WRP with the condition of the windows after 32 years, restoration of the windows after 32 years, paint performance after the restoration, and the final evaluation for decay after 45 years. There was no correlation between the WRE of the treating solutions as measured by the swellometer test and the condition of the windows after 32 years. However, those windows treated with a WRP that was formulated to have a WRE above the industry standard of 60% performed best. The WRP-treated windows were free of decay after 32 years in service but were badly weathered. The severely weathered window units were used to test several restoration methods and wood treatments, henceforth called pretreatments. The restoration involved pretreatments for both the window sash (stiles and rails) and the sills below the window sashes. The window sashes and sills were severely cracked and weathered, and pretreatment consisted of sanding and applying consolidants or WRPs. The use of consolidants as pretreatments was, in most cases, detrimental to the finish, and these pretreatments generally caused increased flaking and cracking of the paint compared with the untreated controls. However, sanding the surface and applying a copper-naphthenate-containing WRP prior to painting greatly improved the service life of the subsequently applied paint system. Pretreating the windows with a WRP after 32 years in service was critical to their continued durability. Windows that did not receive the WRP treatment at 32 years decayed within 10 years after the restoration. 2001 This article is in PDF format (file size: 656 kb). To download this article, right click on the link immediately below and choose "save target as". To view the article, left click the link immediately below.
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Effect of water repellent preservatives and other wood treatments on restoration and durability of millwork   (2001)

This report describes the long-term performance of painted window units that were placed outdoors near Madison, Wisconsin, in 1956. Covered in this report are the effects of the initial water repellent preservative (WRP) treatment during the first 6 years of exposure, a comparison of the water repellent effectiveness (WRE) ofthe WRP with the condition of the windows after 32 years, restoration of the windows after 32 years, paint performance after the restoration, and the final evaluation for decay after 45 years. There was no correlation between the WRE of the treating solutions as measured by the swellometer test and the condition of the windows after 32 years. However, those windows treated with a WRP that was formulated to have a WRE above the industry standard of 60% performed best. The WRP-treated windows were free of decay after 32 years in service but were badly weathered. The severely weathered window units were used to test several restoration methods and wood treatments, henceforth called pretreatments. The restoration involved pretreatments for both the window sash (stiles and rails) and the sills below the window sashes. The window sashes and sills were severely cracked and weathered, and pretreatment consisted of sanding and applying consolidants or WRPs. The use of consolidants as pretreatments was, in most cases, detrimental to the finish, and these pretreatments generally caused increased flaking and cracking of the paint compared with the untreated controls. However, sanding the surface and applying a copper-naphthenate-containing WRP prior to painting greatly improved the service life of the subsequently applied paint system. Pretreating the windows with a WRP after 32 years in service was critical to their continued durability. Windows that did not receive the WRP treatment at 32 years decayed within 10 years after the restoration.

Author: Williams, R. Sam

Source: Proceedings : Ninety-seventh Annual Meeting of the American Wood-Preservers' Association ... Minneapolis, Minnesota, May 20-23, 2001. Granbury, Tex. : The Association, c2001: Pages 84-103

Citation: Williams, R. Sam  2001.  Effect of water repellent preservatives and other wood treatments on restoration and durability of millwork  Proceedings : Ninety-seventh Annual Meeting of the American Wood-Preservers' Association ... Minneapolis, Minnesota, May 20-23, 2001. Granbury, Tex. : The Association, c2001: Pages 84-103.