Foam Scenery on the N Scale Pagosa & Southern

Using Floral Foam and Foam Paste to Model a Rocky Cliff

Scenery work has begun on the N scale Pagosa & Southern! All of the rock work in this photo was modeled using dry green floral foam and my special recipe foam paste. Backdrop added in Photoshop.

I want to keep things very light and portable on my N scale Pagosa & Southern shelf layout. To do that, I've set a goal of using little or no plaster and that has led to experimentation with more foam scenery techniques. I've used Balsa Foam to carve many of the rock formations on the On30 Thunder Mesa layout and I wanted to see if I could also get acceptable results in N scale using far less expensive green floral foam. (Note that I am talking about the dry green floral foam here, often used for silk flower arrangements, and not the "wet" foam that absorbs and holds water.) In practice, the green foam can be carved like a less dense version of Balsa Foam. Fine detail is not really possible and the resulting carvings can be fragile, but I have found that when they are painted and properly blended the results can be quite convincing. I've also found that mixing the resulting foam dust with matte medium creates a very useful modeling paste for blending the rock cravings and other scenic elements together. This foam paste shows great promise and could be a handy scenic material for modelers in all scales.

Top view of the sceniked area, also showing a bit of the staging shelf at left.

Making Floral Foam Rocks

Hobby knives, a sharp pencil, a razor saw and other tools have been used to carve a hunk of dry green floral foam into a rocky cliff wall. The cliff-face on the P&S was made up of four separate carved pieces cemented together and blended in with my special recipe foam paste. 

To seal them and add strength, the carvings were painted on all sides with tan latex paint.

A wash of diluted black acrylic was brushed on to darken all of the cracks and crevices. 

Each section of the cliff-face was then painted with acrylics. Here, a base of dark grayish-tan is being applied. 

Successively lighter colors were then brushed over the surface of the rocks, allowing them to blend and mix with previous coats. Rocks don't have a uniform color in nature and they shouldn't when modeled either. The final color is unbleached titanium, dry-brushed on for highlights.

Here, the first sections of rock carvings are in place and blending has begun using foam paste. The bottom of the creek bed has also been boxed in with 1/4" foamcore and the Kato truss bridge has been painted and weathered with acrylic paints. The tunnel portal is a Hydrocal plaster casting from Woodland Scenics.

How to Make Foam Paste

I stumbled on the idea for foam paste when considering what to do with all of the little bits and piles of dust left over after the carving process. I mixed a little bit of the dust with some matte medium to see if it might be useful for blending rocks together and was pleasantly surprised by how well it worked.

Making foam paste from green floral foam and acrylic matte medium is a quick and easy (if somewhat messy) process. It is basically a mixture of glue, foam dust and pigment and the resulting paste has a grainy, sand-like texture that is great for all sorts of scenic applications. It can be used as a sort of zip-texture ground cover, a gap filling adhesive, and a spackle-like compound for blending rock carvings and castings together. Once dry, it is strong, light weight and can be painted, sanded and carved. Tools clean up easily with soap and water. Working time is an hour or so (depending on how liquid one makes the mixture) and a 1/4" layer will cure completely overnight. Here's how I make it:

First, smash up about 8 oz of dry green floral foam. This is easy to do with your hands or with the butt of a screwdriver. The goal is to create a uniform powder. Yes, it gets everywhere but is easy to clean up with a shop-vac.

Next, pour in about 6 oz + -  of cheep, craft store matte medium. The ratio is about 4:3, foam to matte medium but you really just want enough to wet all of the foam and make a paste.

Stir very well until all of the foam dust is mixed with the matte medium.

Add pigment. This is optional but makes it quicker to work with if it already matches the scenery colors on your layout. I'm adding about a tablespoon of inexpensive raw sienna acrylic paint here.

Mix well again until you get something like peanut butter. This foam paste is now ready to use. I mix and store mine in old jelly jars with airtight lids. It can last for months.

Working with Foam Paste

Foam paste can be applied with a paintbrush, a flat stick or a finger. Here I'm using a wooden stir stick to fill and blend the gaps between two rock carvings. The foam paste sticks very well to most surfaces and dries with little or no shrinkage.  It can be thinned with water or more matte medium if desired.

A thick layer of foam paste was slathered on to glue separate layers of the cliff-face together and to fill gaps around the tunnel portal casting.

Using a wet brush, it's easy to blend the foam paste into carvings and other scenery. In the foreground, a small hill has been created from floral foam and will be covered in foam paste.

Foam paste can also be used to cover ground areas with a convincing soil texture quickly and easily. Just stipple it on with a brush for a form of zip-texturing. Here the foam paste is being applied right up to the edge of the Kato Unitrack roadbed.

For the creek bank, hunks of floral foam were shaped and glued in place before being skinned and blended together with a layer of foam paste. A little water on the brush makes it easy to feather edges of the foam paste where it meets other scenery.

Once the foam paste had cured overnight, colors were touched up and blended with acrylic paints, and various ground foams, trees and other scenic materials were cemented into place.

Finishing Up

Trees, ground foams and other materials from Woodland Scenics and Scenic Express were used to bring life to the scene. With the cliff-face completed I can next turn my attention to modeling the creek where more floral foam carvings and foam paste will be used. I'm working from left to right on this little shelf layout, with the goal of completing about a square foot of scenery before moving on to the next area. I'm pleased with the results that can be achieved with inexpensive floral foam and excited about the possibilities offered by foam paste modeling.

A train bound for Wolf Creek exits the tunnel. More work will be done to blend the Kato Unitrack into the scenery but N scale Colorado is starting to come to life.

That's about all the news from N scale Colorado. Next week I'll return to Thunder Mesa country with an update on that layout's progress. As always, questions and comments are welcome below. Thanks for checking in, amigos. Adios for now!