Concrete and Asphalt Paving Powders

These products are rock powders that will provide a slightly gritty scale texture. They can be applied to any surface that white or yellow carpenters glue will bond to. We have applied the products to Styrofoam, plywood, Homasote, cork, cardboard, matboard, plaster, and Masonite. Why use these products instead of styrene or manufactured ready-to-use material? I consider modeling as a three-dimensional form of art. When you apply a material such as this with even the greatest of care and finesse, those human shortcomings will show up in the finished model. This is what gives the work character and interest to the viewer even if it’s only you. Plaster could be used for roads, streets and sidewalks; however, sanding is required to fix the surface and the plaster dust is a real nuisance to clean up. My downside of plaster is that it sets up way before it smooth enough for a road surface. Our products will have an acceptable natural color right out of the bag, and you don’t really have the weather to surface for a believable scene. Materials;

(#1030 Asphalt Paving Material) or (#1290 Concrete Paving Material)

White or Carpenters glue

Mixing bowl

Artist palette knife

Broad knives from one to three inches wide

Razor saw

120 grit sandpaper

AZ Rock dry color pigment kit #14

Rubbing alcohol for diluting stains

India Ink

Mars Black acrylic paint

The usual variety of brushes, model paints, hobby knives, and eye droppers.

The real fun begins after our products are installed, cured and dry. Concrete will have expansion joints and curbs tooled on the surface. Liquid and powder stains will be applied for the weathering. Asphalt streets and roads can have potholes and patches applied with Acrylic paints and so forth. Before you begin, make some field trips and take pictures of what looks interesting to model. There are two methods for applying the material.

Dry method;

I used this method for a gas station or parking lot diorama on a 1/8 Masonite base. This could be likened to the method used by the Navajo Sand painters. When everything is dry, the base can be tipped to remove the extra sand. I have lately been building urban scenery with streets, sidewalks and driveway aprons appropriate for each situation. I use 1/8 inch Masonite cut to the size that fits a half to full block of buildings including the sidewalks. Any driveway aprons or alleyways are filed and sanded on the edges paper-thin. File and sand the corners to the radius of the sidewalk corners at any street intersections. Lightly sand all curbs to a slight radius. Set your buildings back on this base and see how they fit. These dioramas can be built on the benchtop and assembled on the layout for that urban scene. Now you can make your streets with either our “wet or dry” method.

You can use this method on your already installed bench work except step #7 below becomes more important.

1. Brush full-strength glue on the area to be paved.

2. Flatten the glue with a palette knife to provide an even layer.

3. The glue will begin to dry on you in places, so lightly spray it with water.

4. Sprinkle on the powder as evenly as possible.

5. Use a dry palette knife or bread knife to flatten the powder into the glue base. Don’t let your tool dig into any wet material as it will make lumps in the surface.

6. If globs of glue come to the surface, add more powder and flatten it out with your tool.

7. Keep trawling the surface until the entire area looks slightly damp and stop. If you ended up with a lumpy mess, you can save it by using our “wet” method below starting at step #5.

Wet Method;

This is useful for applying pavement to any area on the layout whiter it’s on a slope or flat. Perhaps you have an old-style gas station where the pump island area was humped for getting those gas tanks absolutely filled. This feature can be added later to the base you built using the dry method above.

1. Pour some diluted glue and water (1 glue/3 parts water) into a mixing bowl. Add powder and stir until you have the consistency of toothpaste.

2. Spoon some mixture on the layout. Even after stirring, the powder will quickly settle to the bottom. The spoon allows you to keep the mix in the right proportions for your work.

3. Begin by working the material into the surface for establishing a good bond. Then flatten it out with a palette and/or broad knife. Now you’re learning what a cement finisher goes through. The thickness should be about 1/16 inch.

4. There will be places that are too soupy on top, so add more dry powder to stiffen it up and continue trawling.

5. Add more diluted glue to any areas that are to dry and can’t be worked.

6. Continue trawling until the area is flattened to your satisfaction.

Custom sidewalks before or after?

 Free handing curbs has never worked out for me as they come out to squiggle and vary in height. A very beat up part of town will have some crumbled curbing. 

I will try this only in short stretches by leaving gapes in the method below. I have successfully used very thin corrugated cardboard cut to size and glued in place. Weight them down until dry because it will curl. When dry, coat with the wet method and apply thinly with a brush and smooth with the palette knife. Brushing on the soupy pigment always requires two coats. Let the first one dry and then quickly do the second so the first doesn’t come loose. Take care to fill the edges of the open corrugations and tool the curb radius as true as possible. When dry, coarse sandpaper can be used to dress up the surface and edges. I used cardboard that was similar to a small USPS Priority mailbox. I use the brass angle that has each side snipped at an angle an 1/8 inch of angle is left one the end. File and sand away the burr left from the snipers.

Tracks in the street or a crossing at grade;

Drag the tool along the guller area where to street meets the curb. Flip to tool over and now drag it to form the curb edge. I use the “wet method” for the areas outside the rails. The pavement will have to be applied thick enough to cover the ties and nearly up to the rail height. Between the rails, clearance must be maintained for the wheel flanges.

 I used a thin matboard cut narrow enough to allow strip wood on both sides for a steel flangeway. Short sections are easier to handle and use full strength glue to hold them to your wood or even plastic ties. Weight them down to eliminate curling. When dry, brush on the wet paving material just enough to cover it. Flatten with the palette knife. Pre-paint the strip wood with a color like “Rock Island Red” (iron oxide) and allow to dry overnight or longer. I hope your cardboard was narrow enough to fit the strips in place and allow clearance for the wheel flanges. Trim the mat board to make this happen. Glue the strip wood where it touches the mat board and install spacers between it and the rail to keep it tight until dry.

This was for straight track. For curves and switches in the street. You’re on your own, however, that same method should apply. Just maintain clearances for those moving parts such as switch points.

Several of my grade crossings are planked with strip wood such as Campbell Scale Models profile Turnout ties. In that case, pave up to the two or three planks outside the rails. I stain them with our #1430 Earth Pigment diluted in rubbing alcohol. Our #1145 Black Pigment us used for the Creosote look on the ends. Slightly dry brush the surface with an off white or light gray for simulated sun highlights to make that effect pop out.

Detailing and weathering;

You can go as far out as the imagination allows. How about a car at the service station with the hood open and steam pouring out of the radiator (cotton) and antifreeze running across the driveway into the street sewer grate (green paint). Asphalt doesn’t lend itself to dramatic detailing like concrete so let’s talk about that. You can pick and choose from this what would also work for tar roads, so let’s move on.

Use the tip of a razor saw or a dull X-Acto knife to score expansion joints in the street and sidewalks. Score down the center of the streets right through any intersections. Newer streets have the curb and gutter as an independent pour. For that score a line down the street about a ¼ inch away from the curb. Now score from the curb to curb for the cross-expansion joints about 10 or 12 scale feet. Use your head and don’t let any scoreline cross like the curb and gutter lines if you made them. The sidewalk curb line is very critical. In HO Scale, mine is about a 1/8 inch wide. Keep that width absolutely parallel to the street side of the curb. If my sidewalk is about 3/4 inch wide. I make the cross joints about that distance apart. Whatever, keep them all the same equal distance. Here again, start the score from the curb score and move your tool towards the building. Now you will know why I never glue my buildings in place as they get in the way for this maneuver. I get my cast metal sewer grates and manhole covers from Durango Press. Carve and/or drill depressions on the pavement for these. I pre-paint them grimy black and weather them with my 1400 rust powder. Older pavement will crack from those heavy trucks and/or winter frost. Score jagged lines in the surface with a sharp tool and keep them random in shape, size, and location. In a couple of places, I carved cobblestones into the street (random size area about an inch or so) and painted them a brick color.

Now, drill appropriate size holes in the sidewalks for fire hydrants, signs, and power poles but don’t install them yet. Sweep or vacuum that and the scoring mess for now. Consider what you want to be painted in the streets like center lines, parking spaces, crosswalks or even RR (dry transfers) for an approaching railroad track. Paint leaks under masking tape so freehand with a brush and paint, or best, colored markers if you can find them. Mark these areas lightly in pencil with a straight edge first to keep things straight. Now get out the Mars Black Acrylic paint and apply it to your street expansion joints, pavement cracks and edges of sewer grates and manhole covers. I sprinkle on a few tabs of my White Chalk Powder #1440 and let everything dry for a spell. Tires leave blackish streaks on the pavement so with a very small and stiff artist brush I apply #1450 Black Powder. Be cautious with the pigment on the brush and have only a track amount on the bristles.

Make random arcs around intersections where cars pealed around the corners. How about horrible skid marks through an intersection? That white chalk powder left in the street, with a stiff brush, tone down all places with a little scrubbing that looks too black. I use the #1440 White Chalk Powder to tone down bright shiny colors on all my railroad structures. I do this while the paint is still tacky, so it imbeds into the surface. I am a “non-dullcote” person except to protect some models from having the weathering smeared through handling. If you did all of this, you’re on your way to becoming an artist in other things as well.

Place your hydrants, power poles, signs, people and vehicles in the scene. The best part is you don’t have to be done quite yet. There are many detail items you can place like, trash cans, phone booth, dogs, jaywalkers, park benches, newspaper stand, pop machines, mailbox, paper trash, cardboard boxes, weeds and a little dirt ( #1090 Earth or #1020 Light Earth).