The organic nature of wood makes it susceptible to abiotic and biotic degradation. Impregnation with chemical products is the most common method of protection. Only inorganic borates combine the unique set of properties that make them well suited for wood protection: they are insecticidal, fungicidal and flame retardants. In this work, zinc borate is suspended in an ammonia solution and applied in depth to wood. Its resistance to leaching is evaluated. The product is tested against rot fungi (Gloeophyllum trabeum and Trametes versicolor) and a xylophagous insect (Anobium punctatum). The results verify its effectiveness as a wood protector, while leaching less than other borate-based products.