Theatre Design & Technology - Fall 2009 - 30

air pockets that give fiberboard its isolative properties averaging a 1.3
R-value (R, means resistance to heat flow. The higher the R value, the
greater the insulating value) [www.templeinland.com]. It is also these air
pockets and soft fibers that make it an excellent sound absorbing material
for stage decking. Traditionally very inexpensive, Fiberboard can often be
found for as little as five to eight dollars per sheet.
A name-brand fiberboard, Homasote, differs in both density and fiber composition from standard fiberboard. Made almost entirely from
recycled paper, Homasote was first introduced to the market in the early
twentieth century and has been recycling paper well before it was fashionable. A detailed history and information about the manufacturing process
can be found at www.homasote.com. With fourteen current products in
production, it is important to identify exactly what product is available locally in your area. One-half-inch Homasote "440 Sound barrier" is most
commonly found at local lumber yards between twenty and thirty dollars
a sheet. With an R-value of 1.2, 440 Sound barrier is manufactured as a
moisture and rodent resistant sound deadening material for floors and
walls of residential and commercial construction. Homasote is slightly
denser than Fiberboard resulting in a marginally stiffer and more resilient
panel with a finer surface texture that accepts paint much better than Fiberboard.. While more expensive, Homasote's unique moisture resistance
and desirable surface characteristics make it desirable for a wide range of
stage scenery flooring and surface treatments.

This allows the panel to be pressed between two large plates, creating
S2S, smooth-two-sides, hardboard. The advantage of this process is that it
requires far less water, however, the process also required much higher
heat, 400 degrees Fahrenheit or more. Finally, as the name implies, dry-process hardboard is created with no added water, and may be S1S, or S2S.
Of greatest importance to stage scenery is the orientation of wood fibers in hardboard. dry-process panels have randomly oriented fibers that
produce a stiffer panel with a higher internal bond (Ib). These random
fibers draw paint directly into the panel and result in a dimensionally unstable panel that is highly susceptible to warping. However, wet and wetdry processes orient the wood fibers parallel with one another to produce
a more flexible panel with better paint-ability. Since paint will remain on
the panel surface, wet and wet-dry process panels are less susceptible to
warping and deformation due to moisture and scenic paint treatments.
This orientation of fibers has a far greater impact on hardboard warping
than the density of the panel.
It can be difficult to identify exactly what manufacturing process was
used to produce the hardboard available in your area since all classifications of hardboard are manufactured using all three methods. It may be
necessary to contact the manufacture to indentify the exact specifications
of hardboard available to you. [HARdbOARd (Masonite) What is it?, by
R.M. Granum, and O. b. Eustis, Panel Processing, Inc, www.panel.com/
uploads/whatisitcda0.pdf.]

Hardboard

Medium-Density Fiberboard

If a fiberboard panel is pressed under extreme heat and pressure it will
eventually become Hardboard. Hardboard is better known to performing arts practitioners under the trade name Masonite, and is sometimes
referred to as "brown board." Invented in 1924 by William Mason, hardboard has an average density of 50 lbs/cu. ft. or higher, making it at least
five times heavier than fiberboard per square foot. It is extremely durable,
resisting marring and abrasion, making it ideal for the finished surface
of stage decks and platforms top skins and facing material. Hardboard
is available in five classes. besides the most common tempered and standard, there is service-tempered, service, and industrialite. ANSI (American National Standards Institute) 135.4 identifies a color-coded stripe for
each class of hardboard. Standard hardboard has one green stripe while
service class hardboard has two green stripes. Red stripes indicate tempered hardboard-one red stripe for tempered class and two red stripes
for service-tempered class. One blue stripe indicates industrialite class.
While hardboard's main adhesive binder is actually the natural lignin in
the wood fibers, some panels have chemicals added to enhance specific characteristics of a panel. Tempered hardboard panels are unique in that a drying
oil is applied and the entire panel is baked to cure and harden the surface to
an average MOR of 6000 psi (versus standard hardboard at 4500psi).
Three different manufacturing methods affect the final characteristics of hardboard:, wet, wet-dry, or dry processes. Wet process manufacturing involves adding water to wood fibers to produce a slurry. The
slurry mixture is placed on a screen to allow excess moisture to drain
away as the panel is pressed under a large plate or roller. The dried panel
is then pressed further under high heat and pressure to produce a final
S1S, or smooth-one-side, hardboard. The textured side of hardboard is
the impression of the screen used in this wet process. Wet-dry processed
hardboard is manufactured in a similar fashion, but with very little water.

developed to address the poor surface characteristics of particle board
for the furniture industry, medium-density fiberboard, commonly known
as MdF, began as a hybrid material to marry the characteristics of hardboard with particleboard. The result was a wood fiber-based panel with a
smooth face finish ideal for lamination with veneers and plastics as well
as direct printing. MdF has quickly become a favorite material for stage
scenery particularity for the milling qualities it possesses. Cutting and routing the material yields smooth homogenous edges ready for painted surface
treatments, requiring no additional filling. Since MdF is a fiber-based panel
rather than particle-based, a much wider range of raw wood materials can
be using in its manufacture than any other wood composite making it potentially one of the most sustainable construction panels available today.
because of MdF's versatility and popularity, product research is developing many new types of panels. For instance, Plum Creek is producing
"super-refined MdF" with ultra-smooth densely pressed fibers producing
heavier but harder MdF panels with increased durability. low-density fiberboard, ldF, is 20% lighter than standard MdF with the same smooth
surface. Poplite Specialty Panels manufactures a full line of lightweight particleboards and plywoods specifically aimed at marine and specialty markets. Poplite, as well as other manufacturers, are now producing hybrid
products like veneer Core, a panel composed of a traditional plywood core
with MdF face veneers to give predictable structural capabilities to an MdFfaced panel. According to ANSI A208.2, grades of MdF include 110, 120,
130, 140, 150, and 160 that incorporate exterior-grade adhesives, and 210,
220, 230, 240 MdF for interior applications. A flexible MdF panel is also
available. Anderson International Trading, Inc, (www.aitwood.com), sells a
specialty bending panel similar to the plywood products, bending birch and
bending lauan. "Neatform bendy MdF" is a reasonably priced pre-kerfed
four foot by eight foot panel with no visible surface grain.

theatre

design

technology

2009

http://www.templeinland.com http://www.homasote.com http://www.panel.com/ http://www.aitwood.com

Table of Contents for the Digital Edition of Theatre Design & Technology - Fall 2009