There are a number of pressure treating methods used today. The one I have read the most about is the typical "pressure" process by which lumber is placed in a cylinder and it is pressurized with the chemicals inside.
But that is a general description for what really has a number of different kinds of pressure treating processes. The ones I have heard about are the a full-cell process, a fluctuating pressure process and the Boucherie process.
That is the extent of my knowledge. You will have to research further at your end as technology continues to evolve.
Hi, can you advise the estimated life of a Titan Deck Foot installed in the ground? How long is it expected to last? I live in an area in Ontario Canada