Dirt tutorial

[Steve]

When the subject of ground cover comes up, we have all probably heard the phrase, “nothing looks more like dirt, than real dirt!”. In the past, I have used commercial ground foam products (with good results) to model dirt, grass, weeds, etc. :



The overall effect can be pleasing, but the three main problems with this method are:
Texture (close up; ground foam’s short comings become more apparent).
Color (modeling different locals can call for particular soil colors that just won’t be available in ground foam).
Expense (dirt is free, or at least “dirt cheap” if you buy in bulk).
I should also point out however, that I have seen spectacular layouts that used ground foam exclusively. To each his own.

There are a few companies that package dirt for model railroading purposes, but because of the high cost, I would advise against going this route unless you need a relatively rare color such as “red desert” or something of that type. Augmenting your local dirt with colored grout could also solve that problem for you.
Getting your own dirt can be as easy as digging a hole in your back yard or bringing a shovel and pail on a walk through the woods. I found a great source for my dirt by chance.  While driving home from work, I noticed a fairly steep grassy hill with a sidewalk at the base. Rains had caused some of the dirt to wash down the slope and onto the sidewalk in a very large area. The dirt had long since dried and I came back with my shovel and bucket and proceeded to do the town a “favor” and clean off the sidewalk. This dirt was of a sandy texture and very easy to scoop up (and easy to sift as well).  Many people advise baking your dirt on a cookie sheet in the oven at about 200 degrees for an hour or so to kill any critters that my be living in there. I, on the other hand, just left mine in the bucket a few weeks out in the garage and had no problems. Running a magnet through the sifted dirt is always a good idea as well.
Now that you have your dirt………let’s get started!

Items needed:
Strainers- I use two strainers that I found in the cooking section of my grocery store (the finest strainer I could find, and one with slightly larger holes).
Nylon stocking- don’t tell my wife!



Containers- 5 or more containers with at least one of them small enough for the stocking to fit over.
Grout- (optional but recommended) color should be close to your dirt color.
Sand- (may be needed for texture variety depending on the make up of the dirt you are using).
Glue- this method uses “wet-water” (water with a few drops of dish detergent or rubbing alcohol by itself) and a 60-40 mix of water and white glue.

Sifting the dirt
Begin the sifting process by using your strainers in succession (large hole, small hole, stocking). Pour dirt into the large holed strainer and sift over an empty container. This first sifting is essentially to clean the dirt and rid it of twigs, rocks, leave particles etc.). The dirt that didn’t fit through the strainer can be kept in a separate container and used as scale “boulders” or pulverized by the method of your choice, and put through the sifting process at a later date.



Note: As you sift your dirt into various scale sizes, save some of each grade to sprinkle here and there on your layout for a more natural look.
Take your cleaned dirt and sift it through the second (smaller holed) strainer. The dirt that was left in the strainer will be put into a container labeled “coarse dirt” and the dirt that passed through the strainer will be labeled as “medium/fine blend”. I found the “medium/fine” dirt to be the grade I used the most (I model in HO scale), so remember to keep the majority of it “as is” and do not sift it further.  
After setting the bulk of the M/F blend aside, sift the remaining dirt using the stocking. The dirt that didn’t pass through the stocking can be labeled as “medium dirt” and the dirt that did pass through as “fine dirt”.



Here are all the grades of dirt side by side:









Now would be a great time to do some tests. Sprinkle the different grades of dirt on a piece of plywood or foam and use the traditional wet-water and diluted- white glue method to glue it down. After it dries, you will be able to determine the grade, or grades of dirt, that suit the scale and look you are trying to achieve.
Depending on the clay content and other factors in your dirt, you may notice that it has darkened after the glue dried. If you would like a lighter result, you can add a lighter colored grout to the dirt, which will keep its color even after the glue dries. How much grout that needs to be added will require experimentation.



Just add  grout a little at a time until your dirt is a few shades lighter, glue it and see how it looks after it dries. The grout also has a side benefit of being even finer than the “fine dirt” that was sifted through the stocking.



On the layout
Here is a picture of the dirt on my layout after the glue had dried:


Notice that the dirt contains dark, medium, and light shaded granules. The naked eye sees it as a blend but the camera really makes the different variations “pop”!
If you would like to add some lighter “dry patches” to your dirt areas, try dry brushing on some of the “fine dirt” (no glue necessary).  It will hold up to any amount of vacuuming and is an easy way to add interest and variety.


The not so finished scene:



Using real dirt requires more work than using ground foam, but the results can be well worth the extra effort……….and let’s face it, we all like to get dirty once in a while…………don’t we?