Southern pine untreated

Douglas-fir, birch, southern pine, and sweetgum blocks were treated with 1% aqueous ammonia or sodium hydroxide for various times, temperatures, and pressures (9). These samples were submitted to soil-block tests with two brown-rot fungi Poria monticola (Madison 698) and Lentinus lepideus (Madison 534) and two white-rot fungi Polyporus versicolor (Coriolus versicolor) (Madison 697) and P. anceps (F 784-5) as well as outside exposure tests (10). In the soil-block tests, the treated wood was resistant to the two brown rotters, but was not resistant to the two white rotters. In the outdoor stake tests, the average lifetime was 3.5 years while untreated controls had an average lifetime of 3.6 years. The outdoor tests show that there is no increase in rot resistance by this treatment. 

Fig. 4.6.9. Correlation of the 1595 cm 1 band height with lignin content of Southern pine wood meal after acid chlorite treatments. Data points in top right-hand corner correspond to lignin in untreated wood...

After fixation, precipitated preservative salts can be seen in the wood structure. Comparison of photomicrographs of untreated southern pine (Figure 22a) and southern pine treated with 2.5 lb CCA/ft (Figure 22b) reveals that the salts in the treated wood form a rough coating on the lumen walls. The exact final location of these fixed salts is still subject to discussion. Undoubtedly, most of these injected hydrolytic preservatives remain in the cell lumen, but the extent to which these preservatives enter the cell wall and react with the cell wall substance dictates the preservative s effect on strength. 

Figure 22. Untreated southern pine shows the absence of crystalline materials. ( X 4(XX)) (a), and southern pine treated with the wood preservative...

Figure 5. Scanning electron micrographs of radially-split southern pine showing swelling of wood treated with methyl isocyanate. Key A, untreated control (245)0 B, 16.0 WPG (224X) C, 32.2 WPG (224X) D, 36.9 WPG (224x) E, 47.4 WPG (224X) F, 72.3 WPG (196X)-...

Drastic alkali resistance tests consisting of heating wood specimens in boiling 10% NaOH for 16 days reduced the crushing strength at the elastic limit for untreated southern yellow pine from 620 to 80 psi and for the wood containing 71% furfuryl alcohol resin from 2650 to 890 psi (56). 

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