A
clinic by Jere Eggleston and Keith MacPhail.
Model
railroading has been around for the better part of a century. Today, the hobby
enjoys perhaps its largest and strongest following, and this trend shows no sign
of reversing, at least in the foreseeable future. A glance at the new
manufacturers and products contained in the pages of the
hobby's various magazines quickly bears this out.
Perhaps
one of the primary explanations for the continued expansion and improvement of
model railroading is the willingness of model railroaders to seek out, and
incorporate into the hobby, new ideas. new techniques, and new modeling
materials. This open minded approach, shared by the vast majority of modelers,
has done more than keep interest in the hobby from stagnating, it has
continuously pushed it forward from year to year, and decade to decade.
Model
railroaders have always embraced new materials and techniques either as
replacements. or enhancements, to existing practices. The purpose of this clinic
is to take a look at a material, extruded foam building insulation, that falls
squarely into the latter category.
The
use of extruded foam panels in model railroading goes back about 20 years, but
it has only really come into its own in the past 5 years or so. From all
indications, extruded foam is destined to become one of the primary layout, and
layout module, building materials, as more and more modelers are exposed to its
versatility and ease of use.
This
clinic will introduce you to the material itself, discuss the use of extruded
foam as both a scenery and benchwork material, examine the basic tools and
techniques for working with foam, explore carving and finishing foam into
fantastic, light weight scenery, and, finally, look at both the pros and cons of
foam insulation as a modeling material. Hopefully,
by the end of this presentation, you'll be encouraged to give foam a try in your
next model railroad project!
Let's get started!
What exactly is Extruded
Foam Insulation?:
A solid, panelized
construction material used primarily in the building trades to insulate building
walls and foundations.
The material is
lightweight, has structural integrity, and is easy to cut, carve, and
"form" using basic modeling tools.
The material is
generally available at lumber yards and home centers, and is most commonly found
in 2' x 8' and 4' X 8' sheets.
Panels can most often be
found in 1/2", 3/4", I'', I 1/2", and 2" thicknesses.
Extruded foam insulation
is produced by:
- Dow Chemical (blue foam)
- Owens-Corning (pink foam)
- Amoco (green foam)
Contrary to popular
rumor, all share the same characteristics, regardless of color.
What exactly is Extruded
foam insulation? (Continued)
Now that we've defined
what extruded foam insulation is, here is a very important note about what it is
not:
Foam
"bead board", packing styrofoam, floral/art foams, etc. are NOT
extruded foams. They are not rigid and do not possess the physical
characteristics needed for carving rock- work and forming scenery contours. More
importantly, these foam products lack the structural integrity needed to
be used as benchwork!
Basic "Tools of the
Trade":
The
following is a list of the tools and materials most often used when working with
extruded foam:
Sharp, straight edged
knife with a 6" to 8" blade (ie: kitchen knife, boning knife, etc.)
Serrated edge knife (ie:
steak knife, bread knife)
Whet stone
Single edge razor blades
Hack saw blades (blade
only) - 24 and 32 teeth per inch
Standard carpenters hand
saw
Table saw (optional, but
useful if available)
"X-acto" knife
with chisel blade and #1I blade
"Hot Wire"
cutting tool
Coarse sand paper
Hand held wire brush -
short bristles
Drill mounted wire brush
(reference the entry for "vacuum cleaner" below)
Face mask or respirator
Bamboo
"ka-bob" skewers approximately 10" length
Water base
adhesive (Construction adhesive PL300, latex contact cement, rubber cement.
etc.)
Pre-mixed lightweight,
non-shrinking, spackling compound
"Sculptamold"
and / or molding plaster
Latex and / or acrylic
paints
Dry pigment paints
Assorted paint brushes
Vacuum Cleaner!! (the
bigger, the better especially if you opt to use a drill mounted wire brush!)
Not all of
the above listed tools are required to successfully model with foam. As you
begin to work with the material, you'll identify those tools with which you are
most comfortable. It is also likely that you'll come up with additional tools or
materials that meet a specific need. Don't be afraid to experiment.
NOTE
OF CAUTION:
If you choose to experiment with any solvent based materials, do
so on scrap foam. in a well ventilated area, with extreme caution.
Solvents will attack extruded foam, often in a very aggressive manner!
Basics of Working With
Foam:
Uses:
Use foam as a Scenery
Material in conjunction with conventional wooden benchwork.
Land forms
Carved rock work
Basic landforms, with
applied plaster rock castings
Use foam as Basic
Benchwork, as well as Scenery Material
Remember, the panels
have structural integrity
Probably best in smaller
scales - Z, N, HO
Laminated panels, laid
flat for around the walls shelves up to 30" wide.
Wider applications, use
strips on edge (ie: 1"X4") to build an interlocked open grid.
Then laminate flat foam panel "table top" onto top side of grid
for layout surface.
"Hybrid"
of foam panels and lightweight framing such as shelf standards and brackets or
light dimensional Iumber.
Bookshelf or around the
walls layout designs
Double deck layout
designs (especially useful when vertical clearances are an issue).
Finish panel fronts with
Masonite or wood veneers
Techniques:
Cutting
the Foam for Basic Shapes:
Carpenters hand saw
Score with sharp knife,
and snap (similar to styrene modeling techniques)
Table saw
Hack saw blade for
curved cuts
Gluing
and Laminating:
Use
only water based adhesives
Apply
glue to each panel to be laminated and press together
If
using latex contact cement, follow package instructions
Use
bamboo skewers to secure panels while adhesive dries; or
Apply
weights to panels while adhesive dries; or
Apply
clamps (even out pressure as much as possible) while adhesive dries
IMPORTANT
NOTE:
White and Yellow Carpenters glues require air to dry. Extruded foam
panels allow very little air to pass through them.
Accordingly, carpenters glue will take a considerably long time to fully
set up (possibly up to several months). Once dried, these glues are very
effective in bonding the foam, however, if you are in a hurry, you may wish to
opt for a latex contact cement. In fact, a latex contact cement, rubber cement
applied as a contact cement, or construction adhesive formulated for extruded
foam application is recommended for use in laminating this material.
Shaping
Scenery Contours:
Recommend removing panel
tongue and groove before gluing
Laminate panels to the
desired thickness for the scenic feature
Horizontal (like a layer
cake) for rolling scenery
Vertical for cliffs and
canyons
For large hills,
consider creating "rings" (full or partial) instead of using
solid panels. Stack and glue the rings (diameters decrease as you go up)
to create a hollow basic lull shape
Even more light weight
Less expensive (use the
cut out material elsewhere)
Great for tunnels - just
leave the top layer or two unglued for an access hatch
Hollow interior can
conceal hidden track
Use hacksaw blades, wire
brush, Stanley Surform tool and coarse sandpaper to "rough in" scenery
shapes
Hack saw blades and wire
brush (especially a drill mounted one) will remove a lot of material fast.
Use the Stanley Surform
and sandpaper to begin to "finesse" the land contours, cut in water
courses, lay in roadways, and shape the track sub-roadbed
Use spackling compound
or Sculptamold to fill in small cracks that may be visible at the joints between
layers.
Laying
Track on Foam:
Extruded foam can be
used as a sub-roadbed material.
Chose a material
thickness appropriate for the scale you are modeling. It's recommended that a
minimum of 3/4" thick material be used regardless of scale.
Use foam blocks for
risers, and glue in place once grades have been established.
Use "
All-Thread" rods with nuts and sheet stock (metal or plastic) cross members
to create adjustable risers.
If creating
embankments, underfill sub-roadbed with chunks of foam, glue, and
contour.
Use bamboo skewers or a
length rigid steel wire to "drill" holes for track wire leads through
the foam sub-roadbed.
Alternatively, plywood
or other more conventional material can be used for sub-roadbed in conjunction
with foam benchwork.
Track can be glued
directly to foam using straight pins to hold it in place while the water based
adhesive dries.
Contour ballast slopes
using a Stanley Surform, sand paper, or a hot wire tool.
Use an X-acto knife with
#11 blade to "slice in" track drainage ditches.
Very
realistic roadbed profiles are easily achievable with foam.
Track laid
directly on foam can be noisy if you are also using the foam as benchwork. It
tends to have a "sounding board" effect. If this is a concern, glue a
cork, Foamcore, Homasote, or Upsom Board roadbed to your foam sub-roadbed. This
additional step will deaden the sound considerably.
"Standard"
track ballasting techniques work the same with foam.
Glue
(construction adhesive) a I/4'' plywood square to the bottom side of the foam
sub-roadbed to serve as a mounting pad for switch machines and other turnout
control mechanisms.
IMPORTANT
NOTE TO TRACK "HANDLAYERS": Extruded foam won't hold
spikes! If youre spiking down your rails, youll need to use a more
conventional roadbed material (such as Homasote or Upsom Board) in conjunction
with your foam sub-roadbed. On the other hand, if you use a Pliobond or PC tie
technique for fastening your rails, you can use foam, cork, or Foamcore for your
roadbed.
NOTE
0F CAUTION:
Extruded foam panels and hot soldering irons do not mix well! Be very
careful when soldering on or near foam. If at all possible, solder your lead
wires to the base of your track rails at the work bench, and feed them through
the lead holes as you lay down the track. If your wire lead hole is a little
off, just poke a new one with the skewer or steel wire!
Creating
Fast, Lightweight Scenery
Extruded
foam is an excellent scenery material
As a base for applying
additional finishes such as rock castings (or a Sculptamold skim coat, though
this step is really not required as we'll cover below).
or
As a final scenery
material in itself. Extruded foam can be carved into very effective rock work,
with very little practice and excellent results.
Basic
Ground Cover (Earth, Grass, etc.):
"Water
Soluble" scenery techniques work great with foam
Paint foam with an earth
colored latex "primer coat"
"Classic" zip
texturing with powdered paint, plaster, and ground foam for basic cover
"Modified" zip
texturing with thick, liquid acrylic or latex paint and ground foam cover
Build up layers - ie:
"dirt", "grass", "weeds", "shrubs", etc.
Work in rocks and
boulders (real, plaster, or carved foam) as you build up the basic cover
Rock
Work:
"Traditional":
Plaster rock castings
will work fine with foam
Attach to foam with
Sculptamold using tooth picks or bamboo skewers pressed into the foam and cut to
length to act as "re-bar" to help secure casting to the foam base.
Color with paints or
non-solvent washes
"New
Wave":
Carve your rocks from
the foam itself!
No added weight
Simulate all rock types
Easy to create very
effective sedimentary strata
Highly realistic results
using a few simple tools
Tools,
and associated applications, for foam rock carving:
Hacksaw: Basic shaping
Carve in strata,
especially coarse sandstone layers
Texture surfaces
Single edged razor
blade: General carving
Texture surfaces
X-acto chisel blade:
Ledge carving
Carving square cleavage
rocks
Carving quarried faces
Surform tool: Shape /
texture surfaces
Soften / blend textures
Coarse sandpaper: Shape
/ texture surfaces
Soften / blend textures
Make sure
your tools are sharp and Watch Your Fingers!!
Coloring
Carved Foam Rocks:
Don't use solvent based
paints or washes (ie: Floquil, Diosol).
Use acrylic or latex
paints.
Thin down latex paints
to flow into carved details.
You'll need to paint at
least a base coat, water based washes don't work on "raw" foam.
Recommend " Apple
Barrel" acrylic craft paints
Inexpensive (retail
price is about 75 cents for a 2oz. bottle)
Cover well, blend well,
and thin well
Flat finish
A whole
"rainbow" of colors
Recommend using a paint
brush rather than an air brush
More control - ie:
individual rock faces
Paint on a primer coat
using a light, neutral color
Fill in "blue
spots"
Use a spray bottle