Borates have been utilized in wood protection systems for many decades but only recently have been used in North America to treat crossties. This colorless, ordorless and very effective wood protection chemical has the ability to arrest and prevent the colonization of wood by both basidiomycete decay fungi and insects such as beetles and termites while ties are air seasoning or in service. Since borates are water-diffusible, they will eventually leach from the wooden substrate if exposed to prolonged outdoor exposure conditions without a water-repellent encapsulation dual treatment. The decay and insect damage that occurs in crossties during the 6-9 month air seasoning process prior to preservative treatment has been determined to be a major factor in the premature failure of in-service crossties. In an AAR/RTA/MSU-sponsored study, DOT borate in a heated 30% wt/wt solution was applied before air seasoning and then standard creosote treatments were applied over the borate treated ties after seasoning. The actual creosote retentions of the original test ties has not been reported in detail and are very important to consider as the commercialization of this new wood protection system matures. It was shown that when ties are properly treated with DOT borate, allowed to establish a distributed borate reservoir, and air seasoned to industry standard, the creosote retentions can be decreased from standard specifications by as much as 50% and tie life can be increased by as much as three times over ties treated with creosote alone at current specifications.

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