New lightweight model railroad scenery
We are often asked how to make lightweight model train scenery. A story on how Macey’s a well known New York store overcame the problem of damage to their floats used in the stores annual parade through New York streets provided the answer. The floats used in the parade were apparently made from polystyrene foam and were easily damaged
The solution as it turned out was to coat the float decorations with one of the new colorless resin which not only strengthened the foam but also prevented it from being damaged during the parade.
A little bit of lateral thinking and some train enthusiasts combined this idea with the manufacture of faux rocks based on waste cardboard boxes and they had a solution to the erection of realistic mountains and rock formations on model railway layouts.
There are many ways the modern foams and resins can be used to provide economic alternatives to the common practice of using plaster as a scenery material.
Plaster can be an ideal material to use for this purpose as it is economical and easily molded or carved into suitable shapes. However it is messy stuff to use and weighs a ton. Many years ago my sons and I constructed a very large HO layout that ran through two rooms in our home. (Yes I had a wonderful wife)
However we had to use a very strong timber base to support the plaster reinforced with hessian that we used for our mountains and scenery, painted I may add, by said wonderful wife. Weight was a real problem and I remember thinking at the time that there had to be a better way.
Polystyrene foam has been used for many years now and has been an effective substitute for plaster being easily carved with hot wires. However polyurethane foam suggested even greater savings if it could be controlled in some way and adapted for shaping into hills and valleys. The idea that developed was to sandwich the foam between two sheet of Glad Wrap or some similar plastic and drape it over preformed cardboard shapes while still flexible.
To give added strength fiberglass mosquito mesh can be used to combine with the foam while it was still expanding. Some has even used other wrapping materials such as bubble wrap to assist in the even dispersion of the foam.
The method is simple. Start by getting a supply of cardboard boxes available free at your local supermarket. By sawing with a small hand saw and then stapling or hot gluing these together you can make almost any type of rock structure. Lay cut strips of cardboard across the tops of the boxes where necessary to support the foam sheets. The foam sandwich is so light that almost any strength of cardboard is sufficient to support the tallest of mountain shapes.
Now lay out a sheet of Glad Wrap kitchen plastic on a table top or bench and cover it with a sheet of fiberglass screen mesh material.
Mix equal quantities by volume of Part A of your polyurethane foam material with the Part B in a suitable plastic mixing cup and mix thoroughly. Pour the mixture over the fiberglass mesh using a squeegee of some type to assist in spreading the material evenly. You could even use a piece of cut cardboard to act as a disposable squeegee for this purpose.
Experience will dictate how much foam to use to cover a particular sized area but to give you a start 15ml (1/2oz) of Part A polyurethane foam material when mixed with 15ml (1/2oz) of Part B will give good coverage for 30x30cm area (1 square foot) This measurement can be simply scaled up for coverage of larger areas.
Now place another sheet of plastic wrap over the top of the poured foam and level the surface by passing the palm of your hand over it. To obtain an even smoother surface if required a sheet of Masonite board can be pressed on top for a minute or so or weighed down with some weights.
The foam sandwich can now be lifted and placed over the scenery area you are building and adjusted to shape while in this flexible condition which lasts for 20 to 30 minutes.
The top sheet of plastic wrap can be removed after 10 to 15 minutes when the foam has commenced to harden. It will take about 24 hours before the foam has completely hardened.
Scenery covered in this manner is ready at this stage for the application of grass, trees and other decorative material. However for those to go a step further and add realistic rock and stone ornamentation, a further exciting step is now possible. This will be covered in a later article.
© Copyright 2010 Aldax Enterprises Pty Ltd www.aldax.com.au