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by Eugene Larson
Copyright © January 2005
There have been many comments lately on the web ship modeling discussion
groups about the comparison between wood and plastic model building. Over
my too many years to want to count of model building I have constructed
model planes, cars, trains and ships from plastic, resin and wood, kit and
scratch, and have enjoyed them all. I have no aversion to any material. In
fact, a recent model incorporates fiberglass, wood, plastic, brass, resin,
and Corian to replace the entire set of 800
"white metal", poor, lead based fittings. See the shop note on Corian.
Although I prefer working in wood, as you can see I have no problem with
model builders using any material available.
However, I remembered the U.S. Navy specifications for ship models which
I last reviewed several years ago. After reading them this month I sent the
following message to Dana Wegner, Curator of U.S. Navy Ship Models.
I think that all model builders should at least be aware of the
specifications and Dana's reply. To be sure, there have been many comments
by model builders that their "very old plastic models" show no
signs of deterioration, but here is a data point to add to your knowledge.
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Dana,
In reviewing the "Specifications for Construction of Exhibition
Models of U.S. Naval Vessels" on the Curator of Navy Ship Models on line website,
the following sentence appears at the end of the second paragraph:
"It is advised that fiberglass resins, styrene, expanding foams, casting
resins, and cyanoacrylate glues be avoided when
other materials can possibly be used."
I see this has not changed for many years. I guess the jury is still out
on these materials.
I wonder what is meant by "styrene", since I now do very
little work in plastics. Is this meant to include all plastic materials
such as those used in the ship model kits, and the bulk materials offered
by companies such as Evergreen and Plastruct? Are
there any "plastic" materials that are acceptable.
One that comes to my mind is acrylic.
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Dana Wegner replied with the following comments, published here with his
permission:
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Gene,
We haven't changed our minds about fiberglass, styrene, resins, and cyano, although I have permitted some specific resin
castings to be used in some models where we can identify and watch those
pieces over time.
Out of the five things on the "no list," styrene plastic is
the worst offender, and the easiest to prove unstable. It is sensitive to
heat, light, and moisture and invariably goes bad given enough time. I
think both Plastruct and Evergreen products are
styrene or a styrene derivative.
Acrylic sheet or block, as a material, holds up well but the adhesives
used to hold acrylic to acrylic are tricky. Some acrylic adhesives form a
layer between the two pieces. These types usually do not last long. The
other types of acrylic adhesive are solvents that melt the acrylic a
little, and then "weld" the two pieces together. The solvent-type
works pretty good and lasts a very long time.
Because it is so brittle we shy away from acrylic except when we can use
it as a single piece with no joints. Clear acrylic block makes a nice
bridge or pilot house and gives the appearance of being hollow, when
actually it is solid. The Blair Company in Springfield
produces displays and exhibits and they have a very old Greek gentleman who
makes all of their models only from acrylic. It doesn't matter if its a building or a missile or a statue. He basically
mills them out of solid blocks. It's an extraordinary way to work, and we
also drop in to see what he's doing and to say hello.
It is not a coincidence, but the plastics which are most permanent are
the same plastics which are impossible to use to build models. The perfect
plastic would be Nylon, Mylar, or Delrin, but you
can't glue them!
Dana
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Copyright © January 2005, Eugene L. Larson
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