Custom Search
|
|
|
||
 contact with soil or water and for important above ground structures exposed to the weather. Since oil-
type preservatives, in addition to affording protection against decay, also retard weathering and check-
ing, they are generally preferable to waterborne preservatives for the treatment of sawn wood that has no
exacting requirements on cleanliness or odor and is to be used in contact with the ground. If cleanliness,
freedom from odor, or paintability are desirable, either of the four waterborne preservatives mentioned
above will give good protection to sawn wood in ground contact provided that the wood is selected for
its receptiveness to treatment and treated to meet the minimum penetration and retention requirements
listed herein.
6.1.3 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 requested, it can be conditioned by the producer to improve its cleanliness.
Difficulties may be encountered in painting wood treated with pentachlorophenol in a light petroleum
solvent. When purchasing wood treated with such solutions, the supplier should be required to desig-
nate a type or brand of paint that will give satisfactory results on wood so treated. Wood treated with
waterborne preservatives should be properly seasoned after treatment (see 3.4) and may require 1 ght
brushing or sanding in order to provide a paintable product. Since "cleanliness" 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 ab-
sence of widely used methods for determining cleanliness, paintability, and water repellency of pen-
tachlorophenol-treated wood, the purchaser may elect to use arbitrary test methods or those described in
Federal specification TT-W-572.
6.1.4 The serviceability of treated wood is impaired through cutting or damage to the treated
surface. Whenever it is possible, machining, cutting, trimming, etc., should be done prior to treatment.
When cutting or damage to the surface of treated wood cannot be avoided, the instructions given in
AWPA Standard M4 should generally be followed. Cut surfaces of wood treated with oil borne preserv-
atives should be given at least two brush applications of either creosote or a solution of at least 5 percent
pentachlorophenol in a suitable solvent, or one heavy application of a grease or suitably bodied preserv-
ative composition containing at least 10 percent pentachlorophenol. Cut surfaces of wood treated with a
waterborne preservative should be given one application of a concentrated solution of the preservative
used in the treatment. (See AWPA Standard M4). The choice should be based upon cleanliness re-
quirements.
6.2 Ordering data. Purchasers should select the preferred options permitted herein, and include
the following information in procurement documents:
Title, number, and date of this specification.
(a)
Moisture content required at acceptance (see 3.4).
(b)
Minimum information required in the branding or marking (see 3.6).
(c)
Treatment other than normally required (see 3.1).
(d)
B-9
|
 
|
|
|
||
