used for wood exposed to severe weathering conditions, such as contact with 

 soil or water and for important aboveground structures exposed to the 

 weather. Because oil-type preservatives afford protection against weathering 

 and checking as well as against decay, they are generally preferable to 

 waterborne preservatives for the treatment of sawed wood that is to be used in 

 contact with the ground. If cleanliness, freedom from odor, or paintability 

 is essential, either of the four waterborne preservatives mentioned above 

 may be expected to give good protection to sawed wood that is selected for its 

 receptiveness to treatment and treated to meet the minimum penetration 

 requirements . The same four preservatives may be used for wood in contact 

 with saltwater where limnoria are the only threat. Pentachlorophenol in 

 a volatile petroleum solvent (Table 33) is ordinarily to be used in above- 

 ground structures, particularly where cleanliness and paintability are re- 

 quired. All the waterborne preservatives (Table 34) are suitable for 

 such use. Pentachlorophenol in a light petroleum solvent is also generally 

 limited to aboveground use especially where moderate cleanliness is desired 

 and freedom from residual solvent is not essential. If water repellency 

 also is desired in order to avoid surface damage due to wetting during 

 storage, it should be stipulated by the purchaser. In some harbors, condi- 

 tions are highly favorable for limnoria, and the life of creosoted piling 

 may be extended by mechanical barriers. AWPA Standard C3 includes a dual 

 treatment that is recommended for trial in harbors where experience has 

 shown that a high limnoria hazard exists along with other organisms. 



Painting of treated wood involves special considerations. Wood treated 

 with creosote, solutions containing creosote, and pentachlorophenol in heavy 

 petroleum solvent cannot ordinarily be painted satisfactorily. When re- 

 quested it can be conditioned by the producer to improve its cleanliness. 

 Difficulties may be encountered in painting wood treated with pentachloro- 

 phenol iu a light petroleum solvent. Wood treated with waterborne preserva- 

 tives should be properly seasoned after treatment and may require light 

 brushing or sanding in order to provide a paintable product. Since "cleanli- 

 ness" is a relative term, it is recommended that the purchaser make known 

 his specific requirements and the end use of the material, and that the 

 supplier be required to furnish evidence that the material be suitable for 

 that use. In the absence of accepted methods for determining cleanliness, 

 paintability, and water repellency of pentachlorophenol-treated wood, the 

 purchaser may elect to use arbitrary test methods which should be described 

 to the supplier. 



b. Timbers and Lumber. 



(1) Functioning Environment . The treatment required for marine 

 timbers and lumber depends on the environment in which they function. 

 Timbers subject to the marine environment but not submerged or intermittently 

 submerged, are treated differently than those that are submerged. The 

 reason being that submerged timbers are subject to marine borer attack and 

 must be treated according to the anticipated attack. 



Unsubmerged timbers are highly subject to fungus attack, particularly 

 where water spray or airborne moisture can frequently wet them, but they 

 cannot be attacked by marine borers . 



An example of submerged use would be the framing and bracing members of 

 a wood pier. Another would be wales, particularly the lower wales of 



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