A mountainous scene with waterfalls and rushing water is probably one of the most dramatic things you can do on a model railroad layout. There is something about this kind of model train scenery that is always exciting. I guess just the fact that you can create such a spectacle of nature so realistically on your layout is amazing to me. You should try to add at least one waterfall to your model train scenery if you have any mountainous or rocky terrain areas in which to do so.
If you already have a rocky area with a flat rock that extends out over the rock wall below it, you’re all set. You want to be sure the waterfall has a straight fall down. Other than the slight natural curve that occurs at the top of the falls, there should be no angle to the falls as the water drops.
You should have a riverbed or lake prepared both at the top of the falls and at the bottom. Remember that the water has to come from somewhere and go somewhere even if the place where it’s going is off the edge of the layout; at least there should be a suggestion that there is somewhere for the water to go beyond the confines of the model scenery.
You will need to make one or more strips of thick (.015"), stiff, clear plastic or styrene sheets or even Plexiglas, cut to the length of the distance between the top and bottom of the falls and the width of the area in which the model waterfall will be placed. If your styrene is not stiff enough, add a layer of 5 minute epoxy to the surface to keep it from bowing or bending after it's in place on the layout.
If you wish, you can apply a small hint of blue or green to the back of the plastic strip/sheet to add a little color, but not too much, which would be unrealistic.
Then glue the plastic sheet(s) in place where you want the falls to be located. Make sure the upper edge of the plastic does not extend above the rocks.
The next step is to apply either clear silicone sealant or high gloss acrylic gel to the plastic in strips from top to bottom. (You may have more working time with the acrylic gel than with the silicone sealant.) Use a wooden stick or toothpick to blend and feather these strips of gel together, so that you end up with a textured finish with an irregular vertical pattern simulating a waterfall. If you end up with a little extra gel at the bottom, that’s okay, because you need to use that for the base of the falls. Use your stick or a stiff small brush to stipple the acrylic gel at the base of the falls where it hits the water. The gel should look agitated here with a thick irregular foamy appearance. (Use reference photos if you need to.)
At the top of the falls streak the acrylic gel over the rocks, blending it into the gel at the top. If you have already prepared a riverbed at the top of the rocks, then extend the gel into the base of the riverbed to form rapids for a few centimeters or more into the riverbed. The rest of the river can be made as previously described in the Model Railroad Water page, using liquid acrylic gloss medium for the base, then, after that dries, use glossy acrylic gel to create the rushing water effects of the rapids, especially in the downstream areas behind rocks and fallen trees. Again, use a stiff brush to make waves and agitated areas in the gel to form the rapids. Use a reference photo to help you.
Optionally, to create the waterfalls, you can apply the gloss medium to the plastic strips at the workbench rather than on the layout; and then incorporate the falls into the layout afterwards.
If you use Water Effects by Woodland Scenics, you will need to make the waterfalls at the workbench by laying out multiple parallel strips (measured a little longer than the top to bottom distance required) of the gel on a Teflon cookie sheet or on wax paper, and then blending and feathering the strips together with a wooden stick as described above, only you will be working on a flat surface instead of on the vertical plastic sheets on the layout. It may take several days or a week for this gel to dry. Once it does, lift it up off the Teflon or wax paper, then apply Realistic Water (also made by Woodland Scenics) to the back of the waterfall. Then press it onto the vertical plastic sheet that you have positioned on your layout. Add a small amount of extra acrylic gel to the edges of the plastic if necessary, so they don’t show on either side of the waterfall. Blend the top and bottom of the falls to your rivers or lakes with acrylic gel as outlined above.
The water beyond the bottom of the falls should be rippled, not flat or calm. Use glossy acrylic medium and a brush to create this effect. After the acrylic dries, use another brush to “dry brush” (apply small amounts of paint to the area by wiping off most of the paint from the brush before applying it to the surface you are painting) the rapids and waterfalls with a hint of titanium white or similar hue. Then use a very small artist’s brush to paint the tips of some of the waves near the bottom of the falls with the same white color.
Then apply another thin coat of liquid high-gloss medium. The falls and waves should really sparkle after this.