Pine and fir can particularly be protected against harsh weather through a vacuum/pressure autoclave treatment using a special impregnating agent enriched with salts. This treatment is highly recommended for wood intended laid beneath the ground.
![impregnati-autoclave](https://www.imolalegno.com/wp-content/uploads/2017/04/impregnati-autoclave.jpg)
Pine and fir can particularly be protected against harsh weather through a vacuum/pressure autoclave treatment using a special impregnating agent enriched with salts. This treatment is highly recommended for wood intended laid beneath the ground.