Here Today, Maybe Gone Tomorrow?
A Shop Feature Reprinted from Nautical Research Journal
Issue 1, March 2000 /By Dana Wegner, Curator of ship models, Department of
the Navy, Naval Surface Warfare Center
See end note.
What I offer here is information and general guidelines
regarding the longevity of certain materials used in ship model building. In
the end, some readers will agree with me, some will accept parts of what I
say, and others will disagree with me wholly. If you disagree with me, please
do not feel compelled to defend your choice of materials. I am only offering
This article relates to static ship models. Certainly,
the special materials needed for floating or operating models may be entirely
different. Some of this information is based on personal observation, and some
of it is based on the large body of technical literature produced within the
international museum conservation field. Museum conservators are scientists
who preserve museum objects such as paintings, books, statues, boats, planes,
glasswork, furniture, and, occasionally, ship models. Several years ago, when
we began investigating the problem of lead corrosion in ship-model fittings,
we found that museum conservators had already studied that problem in
considerable depth, but what they found had not yet been related to ship
models. For the problem of ephemeral or short-lived materials in model
building, we once again turned to the conservation field for advice.
I am neither a chemist nor a trained museum objects
conservator, so I will not use many technical terms. I was once a ship model
builder, but after academic museum schooling and some years as a historian, I
became the curator of the U.S. Navy's collection of more than nineteen hundred
ship models, which date from 1813 to today. The word curator means
"caretaker," and I have been watching over the navy's collection for nearly
The U.S. Navy Collection
Since the U.S. Navy began collecting ship models in 1883, it has acquired them
both by purchasing commissioned models and by accepting donations of models
that had already been built. Living model builders have donated models because
they moved to smaller quarters, had too many models, or did not like models
anymore. Model builders' widows, children and grandchildren, and nieces and
nephews have all offered models to the navy. It has also acquired models
through divorce settlements and by confiscation by the Drug Enforcement
Administration. In sum, the navy collection today consists of models made in a
great variety of ways, by many people, both professional and amateur, over
almost two centuries.
Indeed, ownerships and locations of ship models change
for many reasons. Models can even migrate great distances and survive a
surprisingly long time. Since World War II, the navy's collection of models
has been too large to display in one museum, so an important part of our job
is to lend ship models to qualifying museums and federal offices worldwide.
Since the 1890s, navy models have been routinely shipped across the country.
Some tend to reside in one place for years or decades, but others are
reshipped about every three weeks. In fact, many of the models have been
shipped hundreds of times in their lives and have endured hundreds of
thousands of miles of bumping along in the backs of trucks.
In addition to moving more than 400 models a year, we
repair an average of about 110 a year. There are only two navy ship-model
conservators, so we are really interested in what materials and techniques
tend to last longest and hold up best under physical stress.
In 1883, the U.S. Navy began a tradition of building
one or more major exhibition models to represent new classes of ships, usually
in 1:48 scale. This tradition helps explain why there are more than nineteen
hundred of them today. At first, only the navy had the need and expertise to
build the models, so they were made in-house at the navy yards. However, since
around 1910, when Horace Boucher, a civilian model builder at the Washington
(D.C.) Navy Yard, resigned and started his own company in New York, only some
navy models have been made in-house, while others have been made by outside
Learning from the Navy's Models
Examining older U.S. Navy models and comparing their repair records with
models built more recently have taught us much about how to assure a long life
for a ship model while it is being built. We have some scant early records
about the materials the U.S. Navy used when it began making its own exhibition
ship models. These records dovetail nicely with our curatorial examination of
the models. By examining the models and studying these records, we have
learned considerably more about what materials navy model builders used and
how the models themselves were designed and assembled.
Models from the earliest days of navy model building
were routinely sent to distant national exhibitions such as world's fairs. In
the 1890s, there were no cross-country trucks, so both the models and their
cases were partially disassembled and crated for shipment by boxcar to the
fair sites. Navy model makers traveled to the fairs to unpack and reassemble
the models and install them in their display cases.
We find certain common construction characteristics
when we examine these early models: Gun mounts are pinned, not glued, to
decks; gun turrets are held by pegs to their barbettes; and some heavier, tall
structures, like masts and stacks, probably detach. We can bet that each
smokestack is hollow and made from sheet brass or copper, and at the bottom of
each stack is a screw that mounts it to the deck below. Most rigging that
actually supports something is braided wire. We have also learned to expect
superstructures to be permanently screwed and glued to the deck below. We
think that every model has been repaired many, many times. These early models
were deliberately made to survive frequent travel ,borrowing a phrase, to
"take a licking and keep on ticking."
We have also found that the older models need less
frequent repair than the newer ones. The key to understanding this is that the
number of different kinds of materials available to modelers in the past was
small compared to the number available today. When the navy model builders
built an exhibition ship model in 1883, they made the hull and superstructure
from sugar pine. They glued the lifts together using LePage's wood glue. They
made their own paints from pigments, vehicles, and dryers. They made small
parts for subassemblies from brass, or nickel silver, and soldered them
together. They used linen line or braided wire for rigging. Pine, wood glue,
paint, brass, nickel silver, solder, linen, and braided wire these materials
were basically all they used, maybe half a dozen different things on a given
The chances of material incompatibility become greater
when the number of dissimilar products used on a model increases. The bottom
line is that the larger and more eclectic the selection of materials, the
higher is the risk of material-specific or overall deterioration. Model
builders were probably not aware of the potential for conservation problems in
1883, but the simplicity of their "palette" of materials has inadvertently
helped older models to survive.
U.S. Navy Specifications
World War II, the U.S. Navy built and purchased ship models feverishly, and in
1945 the first curator, Commander Joseph Appleton, a respected ship model
builder himself, devised the first set of written specifications for navy
models based on the experience accumulated by the navy up to that time. He
wrote the specifications to ensure that finished models built for the navy,
whether built in-house or outside, would have a uniform style, a homogeneous
level of detail, and a superior level of craftsmanship. They were also
designed to assure that the models were portable and sturdy enough to last a
long time, in order to justify the government's expense. Appleton's
specifications have been modified a little from time to time, but basically
they are the same today as when they were first promulgated. In the 1960s,
Howard Chapelle began to use the navy's specifications at the Smithsonian
Institution, and most of the models in the famous watercraft and naval history
halls there now were built to U.S. Navy standards. Many maritime museums also
U.S. Navy model specifications are relatively strict.
If you are not already familiar with them, they can be found on the Nautical
Research Guild's Web site and in the March 1994 issue of the Nautical Research
Journal. Over the years, we at the navy have been branded ship-model "purists"
by some. By that, I think people mean that we are traditionalists. However,
you can see that with so many models deteriorating at various rates and only
two people to take care of them, we need to be cautious.
The development since World War II of a variety of new synthetic compounds has
complicated the selection of materials with which to build models. My first
inclination when preparing this paper was to divide new materials into
categories and then comment on every item. Upon reflection, I realized that
there are too many, and what we really need to discuss are some of the modern
materials most widely available to exhibition ship model builders. So let us
start with a controversial one styrene plastic.
In 1839, a chemist
distilling tree resin discovered a material he called styrol, one of the basic
ingredients of polystyrene plastic. By 1934, both Dow Chemical in the United
States and I. G. Farbin in Germany were designing a process to manufacture
styrene and polystyrene to be used as a superior, but expensive, electrical
insulating material. When the Japanese overran Malaya in 1942 and cut off the
Allies' supply of natural rubber, the U.S. government initiated a major
program to build chemical plants capable of manufacturing a synthetic rubber
made from butadiene and styrene. After the war, it was found that the surplus
capacity of these plants could be used to manufacture cheaply huge quantities
of the general-purpose thermoplastic we now call styrene. Styrene is known as
the plastic of the twentieth century: Millions of tons are produced by a large
number of foreign and domestic firms annually.
I well remember those Revell plastic model kits of the
1950s. The injection-molded parts inside the box were made from either acetate
plastic or styrene plastic, and the appropriate adhesive had to be used. (The
labels on the boxes instructed the builder to use either "type A" or "type S"
cement‹ A for acetate and S for styrene.) Eventually, styrene became the
standard material used. Today, in addition to injection-molded parts, sheet
and extruded polystyrene is manufactured and sold in a variety of shapes and
colors, and appears to be a boon to model builders because it has many
desirable properties: It glues well with specific solvents; it cuts, saws,
files, and sands like a dream; it takes many finishes well; and it is nearly
waterproof. Finally, because of its smooth surfaces, the styrene siren calls
out to the modeler of steel ships, "Use me! Use me! I'm perfect!"
But, straight polystyrene has two shortcomings: It has
little resistance to heat, and it deteriorates with age becoming yellow and
brittle, and cracking on its surface. Its aging is accelerated by exposure to
ultraviolet light. (The soft bumper of your car is probably covered with
rubbery "ABS" plastic the S in ABS stands for styrene. You may have noticed
that one of the first exterior parts on your car to fade is the bumper.)
The plastics industry has sometimes combated these
deficiencies by adding ultraviolet absorbers and plasticizers to the formula,
thereby further complicating the basic composition. Correcting one deficiency
may, indeed, create a dozen others. The so-called "plastic of the twentieth
century" has been modified over and over until it has just about any
characteristic manufacturers and consumers want. Different versions of styrene
are manufactured to different tolerances for sunlight, heat and cold, and
impact, and for other characteristics such as tensile strength, smell, color
fastness, or chemical resistance. So now, as with many other modern, highly
processed materials, the trouble with polystyrene is that we just do not know
what we are getting when we buy something called "styrene."
Although it would appear that the usual method of
fusing two or more polystyrene parts together using a styrene solvent
containing a hydrocarbon to dissolve the edges so that it "welds" them
together is effective, achieving lasting bonds of styrene with other materials
is problematic. Some model builders use styrene to sheathe over wood, but this
practice has its own bonding problems. First, the chosen adhesive must join
nonporous plastic with porous wood. There also may be trouble if the wood
substrate expands and contracts at a different rate than the styrene covering
it, causing the styrene to buckle, or the joints to open. Finally, polystyrene
is not compatible with certain types of paint, mainly those containing the
very solvents that make for a good bond. For these reasons, the navy would not
use it on a good model or permit its use on models it commissions. Museum
conservators consider polystyrene generally unstable and of questionable
Plexiglas: A Class "A" Product
In 1975, some museum conservators started a system of evaluating materials
according to how stable they are, or, for our purposes, to how long they will
last in a museum environment. In order of longevity, materials that will last
fewer than six months are labeled class "T," which stands for "temporary."
Unstable or fugitive materials that will last fewer than twenty years are
class "C." Materials in the intermediate class of twenty to one hundred years
are class "B," and materials that will last more than one hundred years, class
"A." Materials that will last more than five hundred years are class "A-1."
Some synthetic polymers are sometimes a thousand times
more stable than similar traditional materials. Acrylic (commonly known by the
brand name "Plexiglas") was first developed in World War II for aircraft
canopies, and the first types tended to yellow rapidly and to become brittle.
However, modern acrylic plastics generally fall into at least the class A
category, and most Plexiglas-like sheet materials are generally acceptable,
even though some technical literature indicates that some acrylic sheets are
inadvertently stressed during the manufacturing process, and that this
invisible defect may manifest itself as mysterious surface cracking at some
future time. Despite its potential usefulness, we have found that Plexiglas is
actually not very popular among model builders because it is a difficult
material with which to work. Its best use seems to be in large, solid blocks
rather than in slab construction. Navy specifications discourage the use of
Plexiglas except in solid blocks, primarily because of the difficulty in
achieving good joints. When Plexiglas is used, solvents should be used to join
it, and paints must be carefully selected to adhere.
the subject of plastics, we should mention polyurethane and epoxy casting
materials. One rule of thumb museum conservators follow is: "If you can smell
it, it's not stable." There are hundreds of two-part casting formulas
available, not to mention polyester resins. Our experience has been that those
that smell after they have cured are likely to shrink, deform, or deteriorate
over time, so I recommend avoiding two-part mixtures that smell like
mothballs, vinegar, or worse after they set up. With this caveat, conservators
generally agree that many epoxies are likely to last a long time and are an
appropriate adhesive and casting material. On the other
hand, expanded polyurethane foams have caused us nothing but trouble because
of their warping and rapid deterioration.
Recently, I thought I would familiarize myself with the various adhesives
available in the marketplace, so I went to our local arts and crafts
superstore. I found no fewer than twenty-eight different products marketed by
Elmer's alone. (Why, they still even make and sell mucilage! Remember that?)
There were sixteen sold under the Loctite label and another six sold under the
Duro name, which, by reading the fine print, I discovered is the same company
as Loctite. So, which products should we use? To find out more about adhesives
generally, I highly recommend Gene Larson's excellent article on the Nautical
Research Guild's Web site. It gives details about various categories of glues
and other adhesives, and their potential applications.
the hot topic is whether or not Cyanoacrylates sold variously as Hot Stuff,
Superglue, and CA are suitable for model building. The basic liquid form of CA
"glue" is a monomer that, when exposed to certain chemicals, rapidly changes
to a polymer and hardens. Minute amounts of water can also start the action,
and most solids have enough water condensed on their surfaces to trigger the
CA was formulated by accident in 1951 by two scientists
working for the Eastman Kodak Company. They were trying to come up with a
stronger, clearer, and more heat resistant acrylic plastic for jet plane
canopies. By 1958, Kodak, which called it Kodak 910 Adhesive, developed a way
to manufacture this material commercially, outside the laboratory and in
quantity. It may have been instant "glue," but it was far from an instant hit
in the marketplace. Apparently, 910 was not widely marketed for domestic use
at first; rather, the first applications were in the manufacture of cameras,
electronic instruments, automobiles, and atom bombs. In 1966 during the
Vietnam War, a surgical grade of CA was used by some combat medical teams. It
worked well, but the product was not approved by the Federal Drug
Administration for general medical use because it appeared to cause tumors
when implanted in rats. Public interest in CA products for general use began
to grow when the inventors suspended Gary Moore on live national television
with a single drop. That feat is still used in some TV commercials.
Early on, CA was prized highly for its optical clarity.
Because it remains largely invisible when used to repair broken glass objects,
museum conservators regularly used CA for glass repairs. But then they found
that some types of glass deteriorated the adhesive. So, while CA is still used
in museums for temporary repairs, conservators now use epoxy or clear
polyvinyl acrylic adhesives, which are rated class A, for permanent repairs.
There are a lot of different CA permutations now being
formulated that have particular viscosities and cure rates for specialized
applications. Cyanoacrylates can be divided into two main types methyl and
ethyl plus, there are also propyl, butyl, and methoxyethyl types. They vary in
consistency from watery to gel-like. Gap filling depends on the type of CA
used. Certainly, viscous CAs can fill gaps well. Regardless of the type, CA is
nearly a class A substance whose magic lies in its ability to form superior
long-lasting acrylic bonds between small surfaces.
CA does have some limitations. It is brittle and has
little strength in shear, being especially sensitive to impact. Some types of
CA are not waterproof, and, like all acrylics, CA generally has a small
tendency to absorb water, though this has not been shown to be detrimental. We
also know that CA is gas permeable, and therefore does not prevent airborne
acetic acid from attacking lead, or ferrous metals from rusting.
Commercial-grade CAs, repackaged in smaller quantities,
are no doubt the type sold by hobby suppliers. We have used industrial grade
methyl and ethyl CAs on navy models for small jobs and quick repairs since
1983. Our uses have included coating bare brass and Britannia fittings and
securing rigging line and we have not seen any evidence of its giving way.
Although there has been some concern that accelerants weaken the bond, we
frequently use accelerants, or "kickers," to speed up the cure, and have not
noticed any difference. However, CAs should not be used exclusively in model
building, however tempting that might be. For larger surface bonds, like
between the lifts of bread-and-butter hulls, or between block superstructures
and decks, I recommend using another adhesive.
as other adhesives go, it seems that polyvinyl acetates (PVACs) are most
popular. These are products like Elmer's Glue-All and Elmer's Carpenter's
Glue. You will find that all PVACs bond wood well, the main differences among
them being their viscosities, drying time, and hardness when cured.
Conservators have found that these adhesives are generally long lasting.
Though they are susceptible to weakening by humidity and water, waterproof
adhesives are generally not necessary for exhibition models. It should be
noted that it may take up to two or three weeks for PVACs to completely cure,
and, while drying, many of them emit acetic acid, which will affect lead if
kept in the same microenvironment. (The navy report on the causes of "lead
rot" in ship models can be found on the Guild's Web site and in the March 1998
issue of this journal.)
be wary of certain adhesives. Our experience has been that contact cements
using volatile spirits eventually dry out and give way after between five and
ten years, depending upon display conditions. One of the ingredients of
contact cement is usually rubber, which is highly unstable, so I would
recommend avoiding resilient adhesives like Walther's Goo (and latex paints,
which are various emulsions in water of a synthetic rubber or plastic).
As a teenaged
model builder, I loved one particular kind of adhesive one that has an
interesting story. Celluoid, one of the earliest synthetic plastics, was first
manufactured commercially in England in 1866. Between 1866 and 1950, it was
used primarily as a substitute for ivory, bone, and tortoise shell. During
this time, a wide variety of things products as diverse as false teeth, movie
film, and ping-pong balls was made from it. Like plastics in general, it was
first belittled as a cheap substitute for more expensive natural materials. By
1900, however, celluloid itself had become a desirable cultural substance.
[Its use became so prevalent, in fact, that the term celluloid (with a
lower-case c) now appears in the dictionary. ‹Ed.] However, it did have some
shortcomings: It sometimes turned smelly, oily, and brittle, and sometimes
shrank and deteriorated rapidly. But its worst problem is that celluloid is
very similar chemically to an early high explosive called gun cotton, in that
it is highly combustible and sometimes bursts into flames for seemingly
unknown reasons! In all, celluloid symbolized at once both what a plastic
could be, and what a plastic should not be.
So, a scientific search began for a substitute for celluloid,
itself at first a substitute. Although the connection is not direct, the search
for a substitute contributed to the eventual manufacture of polystyrene. The
celluloid industry faded away by the 1950s, and today only limited amounts of it
are manufactured for specific uses. One of the few remaining uses of celluloid
is as an ingredient in Ambroid glue, Duco cement, and perhaps some other
so-called model airplane adhesives. (I have fond memories of golden Ambroid,
perhaps brought on by the highs from smelling it, but, seriously, I do not
recommended it for a long-lasting model.)
When the U.S. Navy began building its own exhibition models, it made some of
its paints from powdered pigments, vehicles (like linseed oil or turpentine),
and dryers. These thick, pigment-laden paints were applied in several layers
with a brush. When dry, the surface was polished with a hard felt pad
impregnated with pumice or rottenstone. The superb finish achieved in this way
was as good as, perhaps better than, what we can get today with an airbrush.
And the paints were particularly hardy and colorfast.
Today we are concerned with the "dumbing down" of many
products mainly petroleum-based paints and some solvent-based adhesives. As
you know, to increase consumer and environmental safety, and probably to
mitigate potential law suits, the trend has been toward eliminating spirit
solvents in a number of products. Thus, we have many lines of acrylic paints,
clear coatings, and even contact cements that boast easy, nontoxic water
cleanup. Museum conservators have found that the manufacturer of one such
clear water-based sealant used by artists adds various chemicals to it in
order to allow water to work like a spirit solvent. The result is an unstable
product, filled with complex additives, that covers and dries poorly.
In general, other than traditional watercolors, I
caution against using any paint that cleans up or thins with water, and I
recommend using solvent-based paints as long as they are available. Based on
extensive testing of modern artists' paints, museum conservators have
concluded that solvent-based acrylics generally are stable and long-lived. We
also know from experience that traditional artists' oils, enamels, and
lacquers are enduring. Real varnish and white enamels, however, tend to yellow
with time, so I do not recommend using them on navy models.
Guidelines for Models
Based on the U.S. Navy's experience of caring for its own models and on
conservators' analyses of modern materials, I offer for consideration the
following three guidelines for making ship models that will last.
€ Build it well. Use pins, nails, dowels, and screws
wherever possible to supplement adhesive bonds. Select good-quality,
well-seasoned woods. Avoid lead, balsa, wax, rubber, styrene, decals, highly
processed cheap paper, and ordinary cardboard. Engineer the model so that
masts are strong enough to support the weight of their extremities. Be sure to
attach parts well that will not be accessible later. Never glue anything
directly to a painted surface. Although fine model builders generally know
better, applying adhesives over painted surfaces is still one of the most
common causes of connection failure.
€ Keep it simple. Limit the palette of adhesives to a
minimum number of types and brands. If possible, stick to one type and brand
of paint. Avoid new and untried materials in important models. Suppress the
urge to overbuild models, and use as few pieces as reasonable. Remember: Every
piece fastened on has the potential to fall off.
€ Keep a bill of materials so that, in the future,
there is a record of what and where on the model products were used when it
Guidelines for Display Cases
A few words are due on the subject of display cases. Make sure the model is
mounted firmly on a base that is large and strong enough to protect it when it
is moved or repaired. Keep the model and display case away from sources of
direct heat, cold, vibration, humidity, and sunlight. Avoid exposing the model
to rapid changes in temperature and humidity. And be sure the air in the
display case can change once or twice daily, for the reason I explain next.
All things deteriorate at some rate, and some things
deteriorate faster than others. Even a well-built model will deteriorate more
quickly if it is kept in an adverse environment. Environmental conditions can
retard or accelerate the rate of deterioration. For example, a newspaper
placed in sunlight turns yellow faster than a newspaper kept in a file drawer.
When things deteriorate or change chemically, they release molecules into the
air in a process museum conservators call "off-gassing." When you can smell
paint or glue, whether it is wet or supposedly dry, you are smelling the
off-gassing of those products. Usually the smell diminishes considerably or
seems, according to your nose, to stop altogether. Nevertheless, each material
still off-gasses as it undergoes inherent chemical changes, or as it changes
because of heat, time, humidity, or light. One easy way to tell if your model
is off-gassing is to smell it. If it is more than a few months old and still
smells like glue or paint, either something has not dried yet, or something is
inherently unstable. If the model or the inside of the display case smells
like vinegar, serious decomposition is likely taking place.
Insignificant as these weak gasses seem, when a ship
model is placed in a microenvironment where the air does not move much, like
in a display case, the gasses become relatively concentrated and may begin
interacting in various and unpredictable ways with the materials with which
the model and case were made. Much of the interaction between off-gasses and
particular materials is harmless, but some can be perilous. Think of a display
case as a heatless cooker that will bake a model and anything else within its
Model builders can help retard deterioration by
allowing a little free air into the display case. Air inside even loosely
fitted display cases can be one hundred times more stagnant than the air in
the surrounding room. The air in the exhibit case should exchange at least
once or twice a day. A 1-inchdiameter hole will allow a cubic yard of air to
exchange naturally daily. So, a 1-inch hole is sufficient to ventilate an
exhibit case with an interior of 36 by 36 by 36 inches. Of course, many
modelers display their work without exhibit cases, and if you are willing to
accept some mechanical breakage, that is fine. However, frequent dusting then
becomes necessary, because dust, when combined with humidity in the air, will
form a concrete-like coating that is difficult to remove, even with solvents.
We have learned a lot from more than a hundred years of experience and recent
analyses of modern products. Model builders do not have to build their models
to last a thousand years, but with a little forethought and wise
consideration, they can help preserve their legacies. After we have rung down
the curtain and joined the choir invisible, someday some unfortunate people
are going to have to care for our models. Have pity! Remember, you cannot take
it with you, so you might as well leave something nice behind.
Dana Wegner is curator of ship models, Department of
the Navy, Naval Surface Warfare Center. This article, taken from a speech
presented at the annual conference of the Nautical Research Guild in San
Diego, California (6 November 1999), is published here by courtesy of the U.S.
Naval Surface Warfare Center, Carderock Division Headquarters, but contains
the views of the author, which are not necessarily the views of the Naval
Surface Warfare Center or the Department of the Navy. Nothing herein is meant
to indicate that the U.S. Navy either endorses or rejects any particular
material, product, chemical, or process.