Comparing Ammoniation and Water-Repellent Preservative Treatments for Protecting Wood Window Units from Decay

Window units fabricated from untreated, pentachlorophenol dip treated, or ammonia-treated ponderosa pine were exposed in the field in southern Mississippi to test their resistance to decay. For nearly 4 years they were sprayed with water in the amount and frequency required to promote rapid growth of stain and decay- causing fungi. After testing, disassembly, and longitudinal bisection of each piece of wood, treatments were compared by determining time required for the MC to rise to 30 percent, the minimum amount of moisture needed for fungi to decay wood, and the amount of decayed wood. With either ammonia gas or ammonium hydroxide and high temperatures, treating wood did not prove to be a feasible alternative to the pentachlorophenol-dip treatment for protecting wood window units from decay. Windows fabricated from ammonia-treated wood absorbed more moisture and had less dimensional stability than units made from either untreated or preservative dip-treated wood. In addition, the use of ammoniated wood was associated with a chemically caused paint discoloration and the growth of green algae. After 4 years of exposure, window units made from ammoniated wood had much less decay resistance than those made from untreated wood dipped in pentachlorophenol.

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