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Recommended Retentions
Click on a "Use" above. The recommended retentions
will be displayed.
FOOTNOTES:
(1) American Wood Preserves Association specifications are
the principal wood treating standards used throughout the United
States. By assay procedure-pounds per cubic foot. Retention varies
with species. See referenced AWPA Standard.
(2) Creosote-coal tar creosote. Color: black
(3) Pentachlorophenol may be dissolved with several solvents.
The solvents specified in AWPA P-9 are:
Type A-Oil. Color: light brown to black.
Type C-Light Hydrocarbon solvent with auxiliary solvent. Color:
essentially clear
Use Type C were conditions require cleanliness and ability for
staining.
(4) Ammonical Copper Zinc Arsenate. .
(5) Chromated Copper Arsenate.
(6) Ammonical Copper Quat.
(7) Copper Citrate.
(8) Assay procedure involves laboratory analysis of borings removed
from the treated wood. Assay zone is the portion of the boring
to be analyzed. Measurement shown for assay zone are expressed
in inches from the surface of the product; i.e. 0-.60" means
the treatment zone to be analyzed is .60" from the outer
surface of the product. Retention varies with species; see referenced
AWPA Standard.
(9) Not listed in AWPA Standards.
(10) It is generally recognized that Douglas fir is extremely
difficult to treat with CCA to penetration and retention requirements,
even when incised. Coastal Douglas fir, from a few geographical
areas, has been found suitable for treatment with CCA. Douglas
fir treated with CCA is not recommended for Permanent Wood Foundations
or Pilings.
Penetration requirements for Western Species:
lumber: under 5" thick .40" min. - over 5" thick
.50" min.
plywood: 40% of veneer penetrated
poles: .75" min and 85% sapwood up to 1.6"
piles: 1" min. and 85% of sapwood--marine use
.75" min and 85% of sapwood--foundation use
(11) Not acceptable.
(12) Not recommended in AWPA Standards.
(13) Building Poles - special uses - to be used where replacement
of poles would be difficult and where exceptional durability
is required. Involves requirement for very deep penetration,
i.e. 1/2 the radius up to 2 1/2 inches.
(14) See Section 2 for definitions of moderate and severe borer
hazard.
(15) Dual treatment for marine use involves two separate preservatives;
a waterborne preservative followed by a creosote treatment.
(16) Federal Specifications TT-W-571 is the government specification
applicable to pressure treated products
(17) State specifications may differ, allowing 0.40 retention
(18) Requires second treatment of waterborne preservatives
(19) DOT (Disodium Octaborate Tetrathydrate): a retention of
0.25 pcf DOT is equivalent to 0.17 pcf B203. DOT is a colorless
preservative; colored dyes are typically added so that the treated
wood can be identified.
(20) Assay zone for lumber sizes up to 2 inches thick.
(21) Assay zone for lumber sizes over 2 inches thick.
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