Bakelite and Celluloid — The
Differences
by Julie Pelletier Robinson
People interested in plastics
often wonder what the differences are between Bakelite and Celluloid. As a plastics historian, I can share those
basic differences and the keys to telling them apart without getting overly
technical. To begin, let’s take a look
at the early history of these two revolutionary materials that had such an
immense impact on civilization.
Celluloid came on the scene
during the late 1860s when John Hyatt, an ambitious young inventor, was attempting to win a cash prize by
creating a substitute for ivory in billiard balls. Hyatt’s experiments began in 1861, and yielded success seven
years later when he discovered the action of natural camphor on nitrocellulose
(cellulose fiber chemically treated with nitric acid).
The result was an organic and
chemical dough-like compound that, once cured until hard, could be molded into
shape by the application of heat and
pressure. Celluloid was the world’s
first successful semi-synthetic thermoplastic, but it had one serious flaw: it
was extremely flammable due to the high concentration of nitric acid used in
its makeup.
Bakelite, on the other hand,
was the world’s first completely synthetic thermoset plastic. It was introduced 40 years after Celluloid
in 1909, by Leo Baekeland, a career chemist who was initially trying to develop
a durable varnish for bowling alleys.
Baekeland combined carbolic acid (also called Phenol) with formaldehyde
and ended up with an amber-colored resin that, when heated, turned into a hard
opaque mass.
This phenol-formaldehyde
solid was ground into powder and then molded by heat and pressure into a material
that was practically indestructible.
Dubbed Bakelite plastic by the inventor, it was a chemical miracle and
the 20th century’s first genuine test tube baby.
Differences in appearance and
applications play an important role in deciphering between these two
plastics. Celluloid was clear in its
original state and could be dyed in a variety of ways to imitate expensive
natural materials. Eventually it came
to mimic genuine ivory, tortoise shell, mother of pearl, amber, jet, coral and
even high grade linen in huge quantities.
Sheets of colorful celluloid
were molded into an array of useful and beautiful things, including jewelry,
ornamental hair combs, household and vanity items, billiard balls, dentures,
fancy boxes, cuffs and collars.
Celluloid was an affordable and convincing imitation for costly luxury
materials.
Bakelite, on the other hand,
was a hard, durable molding material that had excellent insulating properties
and thus found its earliest applications in the electrical industry. In its raw state Bakelite was a combination
of ground phenol-formaldehyde and dense filler, like asbestos or slate dust.
This made the material extremely hard, but also very dark, limiting its color
range to black, brown and maroon. Early
applications for molded Bakelite included electrical components, knobs, handles
and telephones.
It wasn’t until the 1920s
that red, green, orange and white (now amber) Bakelite found its way into the
home in the form of colorful and novel kitchen accessories. By 1928, Catalin — a purified form of
phenolic casting resin in a wide range of opaque and translucent colors — was
introduced. It was poured into lead
molds and baked slowly to cure. When
hardened, the plastic was removed from the molds, machined by hand, then polished
by tumbling or buffing.
Cast Catalin, which was more
time-consuming to produce and therefore more expensive than molded
Bakelite, found uses from the mid-1930s
until just after World War II in jewelry,
small personal accessories, kitchenware and novel decorative containers. Stylish and colorful cast phenolic radio
cases were produced in limited numbers up until the 1950s.
The properties of Celluloid
and Bakelite differ greatly. Bakelite
is a dense, durable thermoset plastic
that resists heat and flame. Once
molded, Bakelite and Catalin retain their shape forever. They cannot deteriorate under normal
environmental conditions, and they cannot be recycled - they are here to
stay.
Celluloid, on the other hand,
is a thermoplastic and can easily be manipulated out of shape with the
application of heat and pressure. It
also burns violently if exposed to flame and will deteriorate under certain
conditions due to its semi-organic nature.
So how do you determine if an
article is made from Bakelite or Celluloid?
The easiest way is to use your newfound knowledge about the appearance
and applications of these two materials.
If that fails, then there is a simple odor test that can be conducted
using hot water.
When both plastics are
exposed to temperatures that cause the molecules to move around, they emit
telltale odors. Celluloid will give off
the distinctive scent of mentholated camphor, while Bakelite smells of carbolic
acid (what many refer to as “hot electrical smell”).
In a nut shell, these are the
distinctive characteristics of each plastic:
Celluloid is semi-organic and subject to decomposition. It is a thermoplastic, rendering it pliable
with the application of heat. Celluloid
was made primarily to imitate expensive natural materials that were dwindling
in supply during the late 1800s.
Celluloid was fabricated in a manner that leaves telltale mold lines on
many items. Celluloid emits the menthol
odor of camphor when subjected to hot water.
Bakelite and Catalin are
synthetic plastics made totally from chemicals. Both are thermoset, meaning that their heat-molded shape is set
forever. They are flame and heat resistant
and will not decompose. Durable molded
Bakelite came in a limited range of dark colors. Cast Catalin was carved and polished and exhibits no mold
lines. The distinctive odor of carbolic
acid can be detected from these plastics by heating the surface either with
friction (rubbing a thumb against it) or with hot water.
When I began studying
plastics in 1990 as a student at the Institute for the Study of Antiques and
Collectibles, very little information was available on early moldable
materials. A research paper assignment
led me to explore the subject of Celluloid.
My paper was published in article form “John Wesley Hyatt and the
Invention of Celluloid,” in the June
19,1995, edition of AntiqueWeek.
This
led to the writing of
the book “Celluloid Collector’s Reference and Value
Guide,” by Julie Robinson
and Keith Lauer (curator of the National Plastics Museum) published in
1999 by Collector Books. A new title “Celluloid Dolls, Toys
and
Playthings” by Julie P. Robinson, 2005 Collector Books, has
just been released and is available from
the publisher. Autographed copies may
also be secured from the author, who may be reached at email: JulieRobinson@celluloidforever.com
I frequently am invited to
lecture on the subject and also have built up a following of collectors who
send me celluloid toys and other items for repair.
Reference and Value Guide and
Celluloid Dolls, Toys and Playthings.