I have written a number of posts about loads for open-top cars, including one a few years ago about bulk materials like coal and ore (you can read the post here: http://modelingthesp.blogspot.com/2012/02/open-car-loads-bulk-materials.html ). I came back to this topic in two recent posts about chromite mining and how to model it. (The following link is to a post which also gives the previous link: http://modelingthesp.blogspot.com/2016/10/modeling-mining-part-2.html .) I did receive a couple of questions via email about the loads, and wanted to say more about how I make these.
The first point to recognize about loads like this is where they will sit in the car. A model with slope sheets can have the load sit on the upper part of the slope sheet. A flat-bottom car like a gondola will need a platform to raise the load up to the proper height above the floor.
Then there is the question of weight. Usually my model freight cars are weighted so that they can run all right when empty, meaning that I don’t then want my loads to add too much weight. Thus many of my load platforms are balsa or other lightweight material, and the shape of the load is created by paper mache or similar light material also.
Occasionally, though, a car may benefit by added weight in the load. One example is the resin ballast hoppers once sold by Bruce’s Train Shop in Sacramento, which are awfully close to weightless unless you can add weight somewhere. I have used weighted loads for this purpose.
Several of my loads use a styrene strip as the base for the paper mache, as it is an inert material with respect to a water-containing material like paper mache. The balsa or other platform can go underneath, usually glued to the styrene with canopy glue, an excellent adhesive for dissimilar materials like styrene and wood. (For anyone not familiar with canopy glue, my brief description and comments about it may be of interest; that post can be found at: http://modelingthesp.blogspot.com/2013/05/a-few-words-in-praise-of-canopy-glue.html ).
The photo below shows the bottom of two load platforms after the first construction step. I have glued a platform or base to the gray styrene strip, which was sized to match the open-car interior for which the load is intended. The foreground platform is lead sheet, since this is a load that will sit on the slope sheets in the ballast hopper described above. The lead is from a sheet of roofing material. The longer load is for a 40-foot GS gondola.
The next question is how to represent the load shape. Typically I apply paper mache (Sculptamold or equivalent) to the styrene top of the load platforms, and shape it to whatever kind of loading process I imagine to have been used, accounting of course for the slumping that would have resulted with any car motion. Here are both of the above platforms, seen from above, with the paper mache step completed. You can see that the shorter load, intended to be ballast, has a higher “hump” at one end than the shape of the rest of the load.
To try and show what I mean by load shape, the gondola load, the lower of the two in the above view, is seen in the photo below from a lower angle. This is intended to represent ore dumped from a truck dump, and the car having been moved between truck loads to distribute the load more evenly.
The next step is just like ballasting track. The paper mache part of the load is coated with white glue (or matte medium), the desired bulk material is sprinkled on, and if necessary, more bulk material added and more adhesive sprayed or dripped onto the load, until the desired coverage is attained. Here is my ballast load, made by this method. I used the same ballast that I apply to layout track.
The load fits nicely into the car and matches with about how full prototype photos of SP ballast cars usually appear. The model is lettered for SP Class H-70-11, which is what the model was constructed to depict.
This method for making bulk-material loads for open-top cars is simple, fairly quick, and works well. Loads made this way have held up for years of layout operation. If you don’t have enough loads, or enough of the right kind of loads, or the right loads for specific cars, try making your own. It isn’t very hard, and you get what you want for your cars.