Empty Cell
The objective of the empty-cell process is to obtain deep
penetration with a relatively low net retention of preservative. For treatment with oil preservatives, the empty-cell
process should always be used if it will provide the desired
retention. Two empty-cell processes, the Rueping and the
Lowry, are commonly employed; both use the expansive
force of compressed air to drive out part of the preservative
absorbed during the pressure period.
The Rueping empty-cell process, often called the empty-cell
process with initial air, has been widely used for many years
in Europe and the United States. The following general procedure is employed: