Creosote and penta products are usually treated by an empty-cell process, while lumber treated with waterborne systems is treated by a full-cell or modified full-cell process. For the latter, the wood's SG and MC would be directly correlated to retention; while for the former, the SG and MC would be significant factors but not mathematically related to biocide uptake.
This study examined the within- and among-sample CCA-C retention variation for small defect-free sapwood SYP field stakes treated together by a full-cell process in a laboratory cylinder.
Each set consisted of 20 boards, with each set treated with CCA-C in one charge by a full-cell or modified full-cell process to a target CCA retention of 0.40 pcf.
The amount of preservative impregnated into dried wood that is permeable to the treating solution during a full-cell process should be directly correlated to the wood's air void volume, with the air void volume determined by the lumber's SG and MC (Siau 1971).
This was unexpected, because the stakes were relatively thin (0.75 by 0.75 in.) and were treated by a full-cell process for a lengthy period.