How is plywood made?
Plywood is composed of many layers, which are called plies or veneers. The plies are created from 2 processes:
• The first is Rotary Cut. A log is spun on a roller and a big knife peels off the skin of the log. (Just like peeling an apple).
• The other is Flat Sliced.
The log is sliced into long thin slices lengthwise. (Just like slicing a carrot from head to bottom) The plies are then sandwiched together with a resin (glue) and pressed with enormous pressure. The plywood is then cutinto standard 4' x 8' lengths. Sometimes, depending on the customer needs the sheetscan be as big as 4' by 20' long. If the plywood has more plies, such as, BalticBirch Plywood, it makes it very stable.
There is also many types of plywood, including:
• Cabinet grade, for making kitchen cabinets, furniture, woodworking projects, etc.
• Sheathing, used for siding on homes.
• Marine plywood has a waterproof resin soit can be used for boats and exterior uses.
Plywood is graded by how many imperfections it has. If the plies were clear with no knots, dents, discolouration, it would be considered as Select, #1 or A Grade. If there were plenty of knots and holes it would be lower down on the scale and be called a Shop or Utility grade.
For some people, if they're working on a project and the appearance is not necessary, they choose a “middle of the road “ grade.
When was plywood first developed and what is some background history?
True plywood requires at least three layers of veneer stacked so that the grain
alternates 90 degrees. The veneers are cross-layered and joined together by an adhesive.
The 1993 Hardwood Plywood Reference Guide, a publication of the Hardwood Plywood
& Veneer Association states that, "in 1830, the piano industry became the first
North American industry to use plywood.
Wood & Wood Products Magazine's Centennial
issue (1996) says that, "in 1890, the rotary cutting process was invented," and
as a result of mechanization, plywood became increasingly affordable. In 1929 a
pamphlet published by the National Committee On Wood Utilization noted, "Plywood
is a modern term describing an old product which did not receive serious technical
and economic consideration until its adaptability to airplane and marine consideration
was developed during exhaustive tests at the Forest Products Laboratory."
"plywood" which was created in America, received official sanction in dictionaries
printed a few years later. That's plywood... veneers on the other hand, dated back
to the early Egyptians in the times of the Pharaohs... about 4,000 years ago.
How much does a sheet of plywood weigh?
Plywood weights will vary according to species and even country of origin. A "ball
Park" number for North American made softwood plywood would be 23 lbs for a 4 x
8 x 1/4" sheet.
What is the difference between Luan Plywood and regular good-one-side plywood?
Good one side is a recognized grade for Canadian made Fir plywood. This panel is
obviously made from Fir veneer and bonded on exterior grade resins. The face is
well sanded, repairs and natural defects (knots, splits, etc) are limited.
info try the Canadian Plywood Association, www.canply.org. Laun is a term to reference
a group of wood species. Laun plywood's come in a variety of grades, some of which
are similar to Good one side. Launs are usually bonded with interior grad resins
and are not equal to Fir plywood in structural strength.
What type of wood and sizes do you offer for scroll saw hobbyists?
The ideal wood for scroll saw work is Baltic Birch. This special plywood is constructed
with more veneers per unit of thickness than other types of plywood. Manufactured
in Europe, this panel is ideal for routering, scroll sawing or for applications
requiring high stability.
Available in 5' x 5' sheets and thickness 1/8”, 3/16”,
1/4”, 3/8”, 1/2”, 3/4”. Prices are from $12.00(1/8) - $60.00 (3/4") per sheet.
SHEATHING: Generally broken into 4 grades.
SELECT: Should be solid face, can allow
some veneer splits, no wider than 1/16” knots are allowed, but must be sound and
tight, not more than 1-1/4” in diameter.
STANDARD: Face will be made from “C” veneer,
can have knot holes in face thru 1st layer of veneer only, knots are limited to
1-1/4” in diameter.
D GRADE: All fall down from above, including some face or back
veneer missing or loose.
CULL: Allows for any possible imperfections - delimitation,
off square or miss sized