(For beginner) white birch Plywood knowledge& Manufacturing Experience Part 1 : white birch face veneer (2)

After we knowing that different white birch species and types  (http://www.plywoodinspection.com/2016/03/28/for-beginner-white-birch-plywood-knowledge-manufacturing-experience-part-1-white-birch-face-veneer ),we can know that the quality of the birch veneer are much differents ,especially the natural characterists and dense and color ….Consistency of color cannot be controlled in the manufacturing process, and color variation is not a grading defect.Birch is a medium density hardwood with a smooth surface texture. It has a tight wood grain that is strong and heavy, with a high resistance to abrasion. Birch plywood enable paints, stains and polishes to be applied with perfection.

The birch plywood grade is very subjective ,so ,be careful !

The first step in selecting hardwood PLYWOOD is choosing a species of wood. Each species has its own characteristics, and it’s up to you to decide what you want and need. We offer four types of durable wood that can harmonize with practically any decor. Once you’ve selected your species of wood, you must decide on a grade. It has an impact on the look you want to achieve, and it can also affect the price of the product. Do you prefer a plywood that is uniform or one with knots? It’s simply a matter of taste!

So,how is the manufacturing defects and natural characteristics of the common birch species,all these “SPECIAL ” characteristics and defects are the factors will grade the plywood to different classifications and grades  ,If you don’t konw these ,it is really very difficult for you to grade them and purchasing them ?See below :

Color: In yellow birch (B. alleghaniensis), sapwood is creamy yellow pale while; heartwood is light reddish brown tinged with red. In sweet birch (B. lenta), sapwood is light colored and heartwood is dark brown tinged with red.That is another name ,white birch ,red birch ,natural birch …according to different sapwood and heartwood …

Grain: Medium figuring, straight, closed grain, even texture. Occasional curly grain or wavy figure in some boards.

Variations Within Species And Grades: Yellow birch, sweet birch, paper birch. Paper birch (B. papyrifera) is softer and lower in weight and strength than yellow or sweet birch. However, yellow birch is most commonly used for flooring. Boards can vary greatly in grain and color.

B grade birch : Nearly perfect and flawless face veneer ply. This grade is no longer available commercially.

C: Generally uniform light color, with no plugs, or open cracks/splits. A limited amount of pin knots, and minor color inconsistencies are allowed.

Color: Allows for slight color streaks, slight color variations, and no color contrasts at component joints. Minimum width of veneer components is 6″ for plain slice and rotary cut, 3″ for rift and quarter sawn.

Natural Color: Very strict limitations on size and frequency of pin knots and conspicuous burls. No mineral streaks, bark pockets, or vine marks allowed, and slight allowances for worm tracks.

D: Generally uniform color, though color variations/stains are allowed. Limited amount of plugs, cracks/splits, and unlimited amount of pin knots allowed.

Color: This grade allows color streaks, spots, and variations . There is no minimum width for the veneer components.

Natural Color: No limitations on the number of small burls, pin knots or conspicuous burl sizes. This grade is less discriminating about the size of the repaired knots than a B grade. Also allowable under a E grade are mineral streaks, bark pockets, worm tracks, and vine marks to a greater extent than C grade.

Back Grade :Allowances: Sapwood, discoloration & stain, mineral streaks, sound tight knots and burls, no knotholes, repaired bark pockets, filled wormholes.

This grade accepts colour variations and the wood species’ natural characteristics. Knots of various sizes can be found in the wood. D grade birch is functional and inexpensive because any wormholes, loose knots, splits, checks or other imperfections are filled and varnished. Mill Run A pleasing mix of the natural heartwood and sapwood colours. Mineral striations are allowed, but not checks or holes. It can include knots under 10 mm in size. Select and Better The best-known and most-sold superior-quality grade on the world’s hardwood plywood market. Pale and uniform colours are selected, and this grade does not allow checks or stains. There are no knots in the wood. Mineral striations must be under 3mm X 100mm.

E: Generally less consistent color, more prevalent defects (knots, staining, etc.), and an unlimited amount of plugs.

Color: Color streaks are allowed, as are color variations on the face. quarter sawn, and rift cut panels.

Natural Color: A greater frequency or conspicuous burls and pin knots is allowed, as is a larger size of the burls and knots. Repaired knotholes are also acceptable (to a certain degree) as are bark pockets and worm tracks.

Back :Allowances: Sapwood, discoloration & stain, mineral streaks, sound tight knots and burls, repaired knotholes (1/2″), repaired bark pockets, filled wormholes, limited number of repaired splits and joints.

F: Utility grade; inconsistent color with mineral staining, cracks/splits, larger knots, etc.

Color: Same allowances as F grade with one significant exception. Veneer components must only be 5″ for plain sliced or rotary cut, while quarter and rift sawn components are the same as F grade.

Natural Color: Grade F panels are a little less stringent on the number and size of conspicuous pin knots and burls on the face than F panels. Also, F panels allow for slight mineral streaking, as well as slight vine marks.

BACK :

Allowances: Larger knots allowed, unlimited number of knots up to 1/2″. wormholes, bark pockets, splits and open joints.

Chinese Grade Rules
B/C or B/2 Grade Fairly uniform in color with slight contrasts allowed. Small conspicuous burls and pin knots allowed with a minimum number of scattered sound or repaired knots. Both faces are typically sanded smooth.The “C” back grade is typically more on the C minus to D plus grade or compatible to a #1 and #2 mix back grade on ANSI/HPVA standards.
C/D or C/2 Grade A larger color contrast is allowed. There are a unlimited number of conspicuous burls and pin knots and greater quantity of scattered sound and repaired knots allowed. “Blended Repaired” is allowed whereby splits in the veneer will be repaired with color matched putty. The “D” back grade is typically more on the D minus grade or compatible to a #2 and #3 mix back grade on ANSI/HPVA standards.
D/E or D/3 Grade All defects not permitted by C grade will generally be allowed on D grade. More sound and dark pin knots, repaired knot holes, longer putty repaired veneer splits will be allowed, but the number of knot holes is the major determining factor. The “E” back grade borders in grade and similarity to the #4 or reject back grade on ANSI/HPVA standards.
NOTE: The majority of these panels are laid up on a Chinese Poplar core. IT IS VERY IMPORTANT TO UNDERSTAND THE APPLICATION OF THE PANEL.
B Grade: often used for upper-end cabinetry, architectural millwork, and furniture.
C Grade: used primarily on paint grade type applications, in lower-end case work, and for cabinet interiors in upper-end cabinetry.
D Grade: used for non-visible cabinet parts.

All the grade are very subjective ,custom-made grading rules normally for most of the factories and buyers .

Plywood Grading

AA-Grade Face
Highest quality veneer you can specify in any particular species. The veneer will be smooth, tight cut, and full length and free of any visible defects or abnormalities.

A-Grade Face
An “A” face on hardwood plywood should be matched for both grain and color. All veneer splices should be book-matched for a visually pleasing appearance. There should not be any abrupt changes in color or grain between the splices. An “A” face will not permit sound knots, repaired knots or rough-cut veneer. An A face may allow slight mineral streak and/or vine marks. The number of defects such as pin knots or small burls varies according to the specie of veneer. This is the best face grade on plywood normally stocked and is often used for upper-end cabinetry, architectural millwork, and quality furniture.

B-Grade Face
A “B” face on hardwood plywood should be matched for a pleasing color, but not necessarily for grain. “B” grade faces are generally very similar to “A” faces, but do allow some sound or repaired knots and some slight rough cut veneer. “B” grade faces will also allow slight mineral streak and vine marks.

C-Grade Face
A “C” face on hardwood plywood allows for unlimited pin knots and small burls. A “C” face can also contain repaired knots and sound knots. The “C” grade will also allow unlimited mineral and vine marks. A “C” face should be a sound smooth face. A “C” face is used primarily on paint grade type panels, in lower-end case work, and for cabinet interiors in upper-end cabinetry.

1 Back
Can contain up to 16 sound tight knots not exceeding 3/8” in diameter. Allowed to contain unlimited mineral streaks. A “1” back will not contain any repaired knots.

2 Back
Can contain up to 16 sound tight knots not exceeding ¾” in diameter. A “2” back can also contain repaired knots, rough cut veneer, and unlimited mineral streak.

3 and 4 Back
This is generally referred to as a reject back. A “4” back is to be used in concealed areas where appearance is of no concern. The “4” back is most commonly used on 1/4” plywood. However, it may also be used on thicker panels when the back will.

PARTICLEBOARD
Particleboard is an engineered wood product manufactured from wood chips and a resin. Particleboard is a type of composite panel but it is made up of larger pieces of wood rather than fiber bundles as used in MDF. Particleboard also provides a smooth surface but does not have the strength of veneer core plywood. Because of the coarse nature of the particles, the edges must be treated in some fashion in the finished product. Typical PBC will have low levels of urea formaldehyde (CARB P2 compliant) but can be sourced with no added urea formaldehyde options as a core in decorative hardwood plywood construction.

VENEER CORE
Veneer core is constructed with one or more layers of relatively thick veneers peeled from abundantly available species. These veneer layers (or plies) are laid up and balanced in alternating cross bands for stability and strength. Any decorative thin face of a wood species can be applied to the front and back of the panel. Compared to MDF and particleboard cores, veneer core offers strength, weight and screw-holding advantages.

MDF CORE
Medium Density Fiberboard is an engineered wood product made from wood fiber bundles and resin. MDF provides a smooth surface, but like particleboard it is denser and heavier than veneer core. Typical MDF will have low levels of urea formaldehyde (CARB P2 compliant), but can be sourced with no added urea formaldehyde options as a core in decorative hardwood plywood construction or separately as a raw panel.

Pro-CORE
Pro Core utilizes veneer inner plies in all but those adjacent to the face and back. The outer plies are made of thin MDF to provide the panel with the smooth surface characteristics of MDF and particleboard but with less weight and improved strength.

AA-Grade Face
Highest quality veneer you can specify in any particular species. The veneer will be smooth, tight cut, and full length and free of any visible defects or abnormalities.

A-Grade Face
An “A” face on hardwood plywood should be matched for both grain and color. All veneer splices should be book-matched for a visually pleasing appearance. There should not be any abrupt changes in color or grain between the splices. An “A” face will not permit sound knots, repaired knots or rough-cut veneer. An A face may allow slight mineral streak and/or vine marks. The number of defects such as pin knots or small burls varies according to the specie of veneer. This is the best face grade on plywood normally stocked and is often used for upper-end cabinetry, architectural millwork, and quality furniture.

B-Grade Face
A “B” face on hardwood plywood should be matched for a pleasing color, but not necessarily for grain. “B” grade faces are generally very similar to “A” faces, but do allow some sound or repaired knots and some slight rough cut veneer. “B” grade faces will also allow slight mineral streak and vine marks.

C-Grade Face
A “C” face on hardwood plywood allows for unlimited pin knots and small burls. A “C” face can also contain repaired knots and sound knots. The “C” grade will also allow unlimited mineral and vine marks. A “C” face should be a sound smooth face. A “C” face is used primarily on paint grade type panels, in lower-end case work, and for cabinet interiors in upper-end cabinetry.

1 Back
Can contain up to 16 sound tight knots not exceeding 3/8” in diameter. Allowed to contain unlimited mineral streaks. A “1” back will not contain any repaired knots.

2 Back
Can contain up to 16 sound tight knots not exceeding ¾” in diameter. A “2” back can also contain repaired knots, rough cut veneer, and unlimited mineral streak.

3 and 4 Back
This is generally referred to as a reject back. A “4” back is to be used in concealed areas where appearance is of no concern. The “4” back is most commonly used on 1/4” plywood. However, it may also be used on thicker panels when the back will.

 

 

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