The timber is transferred into the treatment vessel.
A vacuum pulls the air out of the vessel.
FirePRO® preservative fills the vessel.
The vessel is pressurised forcing the preservative into the timber.
The preservative is removed and final vacuum is applied removing excess.
The timber has now been preserved with the FirePRO® preservative.
This Koppers animation explains the pressure treating process typically used to treat wood with preservatives for residential, agricultural and commercial uses.