When wood is manufactured, it has a high moisture content. Even “kiln dried” lumber is no longer held to the strict standards of moisture content (19-21% for framing lumber and 9-12% for finishing stock) as was the case before the recent housing boom. Pressure treated lumber is supersaturated with water born preservatives and is typically not dried, except for the vacuum applied in the retort. Consequently, it is full of water and must be allowed to “air dry” sufficiently to be receptive to stain. This can vary from a few weeks to a few months, depending on the time of year of installation.
As wood dries in the open air, it shrinks, which causes some longitudinal cracking, which runs “with” the grain of the wood. This is normal and unavoidable. Larger deeper cracks in the wood are generally the result of neglect, and result from water sitting on the deck in the winter, seeping down into an initial very small crack, then freezing which causes expansion. This pushes the wood fibers apart. PERMANENTLY. These cracks will never close again. But our restoration process smooths the edges of them, and our sealant makes the surface smooth with a low coefficient of friction. This lets your patio furniture slide easily over such cracks without causing splintering.