Penetração e retenção do preservante em Eucalyptus com diferentes diâmetros

Abstract

It was aimed to assess the effects of diameter class and moisture over penetration and retention of CCA-C (Chromated Copper Arsenate type C) on a Eucalyptus urophylla clone wood preserved in autoclave. 36 fence posts were used, belonging to the diameter classes of 7, 9, 11 and 13 cm, which were separated to three outdoor drying times: 20, 40 and 70 days. For wood characterization per diameter class, were determined basic density; sapwood percentage; treatable volume; the length, width, wall thickness and diameter of the fiber lumen; average vessel diameter, frequency and area occupied by vessels; the total lignin content and total extractives content; besides the pretreatment moisture values, general and only sapwood. After the preservation in autoclave, the treatment quality control was made, by analyzing the CCA-C preservative penetration and retention. In general, the penetration of preservative solution was considered deep and regular into the sapwood, regardless of diameter class and drying time to which the wood was submitted. Retention in fence posts of the 7 cm class was higher than those of 9, 11 and 13 cm classes, which did not vary statistically between themselves. The increase in drying time from 20 to 40 days resulted in significant increase in average retention of CCA-C by fence posts, from 5.70 to 6.67 kg A.I.*m-³. The variation of anatomical and chemical characteristics, in addition to the density, sapwood percentage and treatable volume, between the diameter classes, when they occurred, have not contributed to explain the retention values of CCA-C. The variations of the general moisture and the sapwood one showed significant variation with the retention, showing good correlation between the factors. The correlation between the fence posts general moisture and retention of CCA-C was stronger than the correlation between sapwood moisture and retention.