This photo of an adobe CONOCO gas station was taken before it was placed in its final location on the layout.
Unfortunately, many of the buildings on my layout lack the Northern New Mexico style of architecture. While most of the railroad related buildings are appropriate to the location and era that I model, many of the other structures do not. To truly represent Northern New Mexico, I would need a larger percentage of my structures to be of adobe or stucco construction.
New Mexico's adobe and stucco building construction techniques blends Indigenous traditions, such as using earth/mud as mortar between layers of stone, with the Spanish introductions of standardized sun-dried adobe bricks. Adobe, and later stucco buildings in New Mexico are often referred to as the Pueblo Style which later became known as the "Santa Fe Style". This is also true for other southwestern states.
What we typically refer to as adobe construction was influenced by the Spanish settlers and missionaries that came here between the 1600s and 1800s. Spanish colonists introduced wooden molds to create uniform adobe bricks. Adobe is a mixture of earth (clay, sand, silt) combined with water and an organic binder like straw, grass, or dung, molded into bricks and sun-dried. This technique merged with existing Indigenous methods. This ultimately lead to iconic structures like Spanish missions, government buildings, large ranchos, and small homes.
From the 1800s to present, often referred to as the Territorial & Revival Eras, there was a major material and construction shift. During the U.S. Territorial Period, lumber became more common, but adobe remained, for cultural and economic reasons, an important building material. What is referred to as the "Santa Fe Style" became prevalent in the 1920s. Artists and architects promoted a uniform "Santa Fe Style" based on Pueblo & Spanish Mission designs to boost tourism, using stucco-covered adobe. After the 1920s wood frame structures with stucco siding became prevalent. Stucco is primarily made from a mixture of Portland cement, sand, and lime, combined with water. It is a protective coating applied to walls over other materials like cinder blocks, or wire mesh over “plywood” on a wood frame structure. The major difference is function and durability. Adobe is the wall structure while stucco covers the wall. On historic adobe buildings, mud was used to cover the walls. You will note in the photos below that the stucco and adobe structures do not all have the same finish coat. The size of the sand grains in the finish/surface coat determines how rough the surface coat is. The engine facility and the CONACO gas station have a rough surface finish. The other buildings have a less rough finish.
I should point out that just about all my structures are built on a framework of MDF (medium-density fiberboard). Depending on what I'm building I use 1/4" (photo below), 3/8", or 1/2" MDF. The four sieves on below are used to separate the sand into the grain size that I need. When I need sand for ground cover or for making stucco I just go outside my train building a scoop up a bucket full. I then use the sieve that I need to get the grain size that I require. Where I live the sand is much finer than beach sand. I can sieve it down to less than 420 microns (.0165 inches).
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Depending on the stucco/adobe finish coat that I want, I will mix the desired sand grain size with either DAP DRYDEX spackling. Or I will use DAP Stucco patch. The stucco patch already has texture. On the CONOCO station below I used .034" sand mixed with the heavy weight DAP spackling. It was applied directly on 1/2" MDF. Adobe bricks come in different sizes. Over the last couple hundred years the size of a brick has changed significantly. From about 1700 through the 1800s there was no standard size. Starting in the late 1800s a “standard” adobe brick was 4” x 10” x 14”. Half inch thick MDF scales out to 10.15”.
Photo on the left shows the four sieves that I use most often. The photo on the right is 1/4" leftover MDF. It's thick enough for scratch building wood framed wood sided structures.
The small dilapidated building on the left side of the gas station was made with individual pieces of ½” thick Homasote board (sound board). Yes, the tree is growing in the middle of the building. That's not too uncommon around here.
In the photo on the right you can see how much sand was mixed with the spackling. Also note that the finish is rather rough. The gas station is intended to represent an adobe building with a cement stucco finish. That was fairly normal between the 1920s and 1940s in New Mexico.
My 3-stall engine house was built with 3/8” MDF. The side walls are intended to represent stucco over cinder blocks. Cinder blocks are 8" X 8" X 16". In F scale 8" would be .39". 3/8" MDF is ~ .38 inches. That's close enough by my standards. The sand used was the same as what was used on the gas station. I used less sand in the spackling.
This old cantina was made from ½” MDF. The adobe bricks were carved into the MDF. The adobe bricks on the ground were also made from MDF. There isn’t much left of the adobe surface coat. Note that it has a smooth surface. That means that there was no sand available to add to the mud surface coat. The cantina represents a building constructed between the 1860s and the 1880s.The small, attached building on the backside is an icehouse. It has thicker walls and a thicker surface coat.
The building on the left was made of particle board. In a few select places adobe bricks were carved into the side walls. A rough stucco finish was applied to the surface of the rear and side walls using DAP stucco patch.
I have no idea what I had in mind when I built the pump house. It's probably brick or cinder block with a stucco finish. The oil storage facility goes on the outside part of my layout.