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The American hardwood grading
system was originally developed for the domestic industry and is widely used in many
markets around the globe.
However, there is not a formal set of international rules because the domestic hardwood
industry in 50 different overseas markets follow its own individual requirements. Each of
Japan, Mexico, Germany and the UK, for example, have different requirements which must be
agreed on a mill by mill basis between the two contracting parties.
The governing authority in the US is the National Hardwood Lumber Association (NHLA). In
practical terms, NHLA rules are the basis for WZ®'s lumber products.
This means that in practice, EXO-TIMBER® and MULTI-TIMBER®
products are graded on the basis of NHLA rules, with modifications and exceptions.
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Method of
Measurement:
The NHLA grading system is based upon the cutting unit method, which estimates
yield on a theoretical basis. There is a difference between saw milling exotic hardwoods
and saw milling American hardwoods, since the exotic hardwood mill uses a system with
cross cutting methods to eliminate defects, whereas American hardwood mills break down the
log into wide boards, and defects are retained for elimination by the end-user.
Accordingly, the quality of EXO-TIMBER® (milled in Brazil) is
generally higher than the quality of MULTI-TIMBER® (milled in
the US).
Illustrated below, with a brief description, are some of the various grades of EXO-TIMBER®
& MULTI-TIMBER®:
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EXO-TIMBER®
& MULTI-TIMBER® PRIME
(similar to US Grade: FAS)
For the most part blemish free. PRIME Boards are in
demand as a top quality material for furniture
production and various other applications.
Example PRIME
Example PRIME
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FAS
The highest grade is FAS (Firsts and Seconds), which provides
users with long, wide, clear cuttings for high quality furniture, interior joinery and
solid wood moldings. This grade includes a range of boards which yield from 83,13%
(10/12ths) to 100% clear wood cuttings at least 3" wide by 7ft long or 4" wide
by 5ft long.
FAS 1F and Selects
In FAS 1F (Firsts and Seconds, one Face) and Selects,
the grade is established using both faces of the board. The best face must meet the
requirements for FAS, and the reverse side must essentially grade as Number 1.
FAS 1F and Selects are virtually the same grade, except for minimum width
and length. The minimum board size for Selects is 4" by 6ft; and for FAS 1F it is
6" by 8ft. |
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EXO-TIMBER®
& MULTI-TIMBER® 1. CLASS
(similar to US Grade: No. 1)
Widely used for furniture production and a wide
range of other uses where a quality type of lumber
with a fine appearance is required.
Example 1.CLASS
Example 1.CLASS
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Number 1
Number 1 grade provides the user with clear cuttings of medium length and
width which are best suited for furniture, cabinets and a multitude of solid wood
manufactured products. The Number 1 grade includes a range of boards
which will yield from 66,23% (8/12ths) to 83,13% (10/12ths) clear wood in cuttings at
least 3" wide by 3ft long or 4" by 2ft. |
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EXO-TIMBER®
& MULTI-TIMBER® 2. CLASS
(similar to US Grade: No. 2)
Used for a variety of industrial purposes, mainly for
use in unexposed furniture frames, flooring etc.
Example 2.CLASS
Example 2.CLASS
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Number 2
Number 2 grade provides users with short, narrow, clear cuttings
economically priced, for use in unexposed furniture frames, picture frames, cabinet rails
and frames, parquet or strip flooring, and many other smaller solid wood components.
The Number 2A grade includes a range of boards which will yield from 50%
(6/12ths) to 66,23% (8/12ths) clear wood in cuttings at least 3" wide by 2ft long.
This grade is included in the general classification of Number 2A Common,
but 2A should be specified if clear cuttings are required. |
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EXO-TIMBER®
& MULTI-TIMBER® 3. CLASS
(similar to the US Grade: Sound Wormy).
Example 3.CLASS
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3.
Class
Sound Wormy
Same requirements as #1 Common and better but wormholes, limited sound
knots and other imperfections allowed. |
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The
Grading System:
The American hardwood lumber grading system is based on the size and number of cuttings
(pieces) which can be obtained from a board when it is cut up and used in the manufacture
of hardwood products such as furniture, flooring, mouldings or joinery. It is a yield
system. Cutting is based on clear cuts, so that splits, bark pockets, rot and other
defects do not appear in the finished product.
Usually the buyer intends to use only the clear (defect free) material in a board. A
higher grade implies a larger area of clear wood. In other words, the higher the grade,
the larger the area of clear material contained in an individual board. This means that
the upper grades will yield a larger proportion of the board in a few large-sized clear
cuttings, while the lower grades will yield a smaller proportion of the board in a greater
number of small-sized cuttings.
Generally speaking, the higher the grade, the higher the price of the board.
Because the grading rules are based on the yield of clear wood, many of the beautiful
natural characteristics which appear in a board are not included in the calculation of the
yield. Often, the natural beauty and real bargains are not found in the most expensive
grade of lumber. The keen buyer who examines the lower grades can discover that they may
'yield' the prize pieces. The relationship between yield and cost is therefore very
important. |
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Nominal
Size (Fraction In) |
Rough
Size (Inches) |
Surface 2
Sides
Actual Size
Dry (Inches) |
| 4/4 |
1 |
13/16 |
| 5/4 |
1 -1/4 |
1-1/16 |
| 6/4 |
1-1/2 |
1-5/16 |
| 7/4 |
1-3/4 |
1-1/2 |
| 8/4 |
2 |
1-3/4 |
| 10/4 |
2-1/2 |
2-1/4 |
| 12/4 |
3 |
2-3/4 |
| 14.4 |
3-1/2 |
3-1/4 |
| 16/4 |
4 |
3-3/4 |
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 Back to the EXO-TIMBER Main Page 
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