Borates are increasingly used as components of wood preservative systems for railway cross ties (“sleepers”) in the USA. A variety of methods exist for incorporating the borate component; however, the so-called ‘two-step’ treatment, which involves treating the green tie in borate, followed by a pressure treatment with creosote or copper naphthenate after drying (‘seasoning’), offers the unique potential of protecting the tie during drying from incipient fungal decay. Sets of oak and mixed hardwood ties, either with or without borate pre-treatment, were set out for drying at commercial tie yards in two locations in the USA. After the ties dry to levels suitable for pressure treatment, they are being tested for mechanical properties, using tests commonly employed in the rail tie industry. Fungal mycelia masses have been observed on untreated ties; however mechanical testing of the most rapidly dried ties did not provide evidence for treatment differences. It can be concluded from the results that if proper and rapid untreated tie processing can be carried out significant losses of wood performance are unlikely. Such conditions probably include avoidance of dead stacking at sawmills and on rail car gondolas for any period of time and take down for final treatment immediately that the ties reach the appropriate moisture content. In the event that such processing cannot be carried out, the application of the borate is best done as soon as possible on the tie in its green stage and prior to seasoning.

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