Modeling an acid tank car

A couple months ago, I reviewed John Riddell’s fine new book, Canadian Car & Foundry, and included in the review several builder photos. They weren’t entirely chosen at random; each had some modeling interest or specific freight car history content as well. (You can read that review at: https://modelingthesp.blogspot.com/2026/08/an-excellent-new-freight-car-book.html .)

One of the images was a 1931 photo of a brand-new acid tank car. It was built for Consolidated Mining and Smelting Co. of Canada, headquartered at Trail, British Columbia, site of what was at one time the largest lead/zinc smelter in the world. That photo is repeated below. 

So why would a smelter company own acid tank cars? The sulfur dioxide by-product of smelting is not only environmentally damaging if released, but if recovered, can readily be converted to sulfuric acid and sold as an additional revenue stream. Cominco (as the company was often known) owned 14 of these acid cars, numbered CMSX 1–14.

I should mention that the car shown above is readily recognized as an acid tank car because of its dome. Acid cargoes were normally unloaded by suction up through the dome, rather than draining through a bottom outlet, so this is not an expansion dome. The AAR code for cars without bottom outlets, a suffix letter “A” for acid, means that this was an AAR Type TA car.

These cars are listed in the Official Railway Equipment Register as 5900-gallon capacity; those are Imperial gallons, which convert to 7085 U.S. gallons. Tangent Scale Models offered a very nice 7000-gallon  acid tank car some years back. I acquired several of them; I reviewed one at the time (see my post at: https://modelingthesp.blogspot.com/2014/11/a-terrific-new-tank-car-model.html ). They follow an AC&F prototype, but look quite similar to the CC&F car shown above.

I knew that Black Cat Publishing (Winnipeg, Manitoba) had a decal set for this lettering scheme (set CMSX1); you can see their line of decals at this site: https://www.blackcatdecals.com/product-category/ho-decals/private-tank-cars/ . One of the Tangent models I purchased was undecorated black, for future decal application. Yes, one handrail on the dome platform needs to be replaced; I used brass wire.

This model does have a dome platform, which the CMSX cars originally did not, but some car owners did apply these in later years. I don’t know whether or how many of the CMSX cars were so modified, but here is the model photo included on the Black Cat Decals web page, with credit to Lyall Falk included. On this basis, I chose to leave the dome platform in place, though this looks more like a high-pressure valve bonnet than an acid dome.

Decal application was straightforward. Every Black Cat set I have ever used was high quality and easy to work with. Incidentally, the white diamond provided in the decal set for the side of the dome is incorrect. That diamond denotes an “approved manway,” which acid cars did not have. Here is the model, still awaiting placards and weathering (separate topics, in some ways). 

To operate this car on my layout, of course, it needs a waybill, and here is an example of what an inbound bill might look like. 

This is an interesting tank car, being as it is from western North America, and I expect it to show up from time to time in my operating sessions.

Tony Thompson 

Car Distribution

The title of this post is that of a railroad job, the person responsible for maintaining the inventory of active cars on the railroad, foreign and domestic, and fulfilling requests for empty cars. I have written two prior posts on this topic, beginning with a general description (see: https://modelingthesp.blogspot.com/2020/12/whats-car-distributor.html ) and following up with additional information (that post is at: https://modelingthesp.blogspot.com/2021/06/more-about-car-distributors.html ).

Yard offices in the steam era did all kinds of paperwork, including distributing empty cars. The photo below is of the Santa Fe yard office at Amarillo, Texas in November, 1942 (John Vachon photo, FSA-OWI Collection, Library of Congress negative LC-USW3-011438-D). The gentleman in the light Stetson is the yardmaster.

This photo depicts a modest amount of staff; doubtless not everyone is shown. But in a truly large and busy yard, such as Southern Pacific’s Taylor Yard at Los Angeles, the numbers were bigger. In a previous post about this topic (see it at: https://modelingthesp.blogspot.com/2018/05/clerks-waybills-and-all-that-waybills.html ), I showed several photos of the staff at this office; one of them is below. These men are identified in the post cited.

Amongst all these people and their manifold duties is a Car Distributor. It can be an important concept to understand for layout operation to achieve realistic movement of empty cars.

And the core operations point, referring to car distribution, is “where do empty cars come from?” The prototype answer is that there is a “reservoir” yard, to which every town agent addresses requests for empties, and from which every town receives them. This is often easy to research if you have access to an organization chart or, better, a list of railroad officials. Car distributors were only in charge of reservoir yards. 

That doesn’t mean that empty cars never came from anywhere else. But the common model railroad move, of a car made empty in a town, then being used at another industry for loading, was a rare occurrence on the prototype, as several experienced railroaders have commented. The timing, and having the exact car type (and grade) that was needed, being available, was pretty unusual. 

So how was this administered? On the Southern Pacific, empty car movement was the responsibility of the Transportation section of the Operating Department. Car distribution was under the supervision of the general superintendent of transportation. Under him, Freight Car Service was the specific duty of its superintendent. These officers were located in San Francisco. 

On Southern Pacific’s Pacific Lines, the railroad west of El Paso, there were ten operating divisions. There was, in general, one Car Distributor for each division, with two exceptions. The very long Salt Lake Division had a Car Distributor at each end, Sparks, Nevada, and Ogden, Utah. And the immense Western Division shared Oakland Pier and Stockton. 

They were as follows: San Francisco (Coast Div.), Oakland Pier and Stockton (Western Div.), Sacramento (Sacramento Div.), Ogden and Sparks, (Salt Lake Div.), Dunsmuir (Shasta Div.), Portland (Portland Div.), Bakersfield (San Joaquin Div.), Los Angeles (LA Div.), Tucson (Tucson Div.), and El Paso (Rio Grande Div.). 

A good summary of the topic of SP car distribution comes from an article in the SP employee magazine, Southern Pacific Bulletin, in the issue for September 1951: 

“The car service department at San Francisco supervises the tide movement and allocation of empty freight equipment over the ten divisions of the Pacific Lines with an ever watchful eye on economic factors, consisting of maintaining minimum per diem expenses, empty freight car miles, and the flow of empty freight cars through the several gateways of Pacific Lines from the north, south and east.” 

I remember from my interviews with Malcolm (“Mac”) Gaddis, who had worked at San Luis Obispo or SLO in the early 1950s, that I asked him where empty cars came from. He answered, “Usually Los Angeles,” and when I asked how that worked, he said that most days, the afternoon train from Los Angeles, the “San Francisco Manifest,” would have a string of empties in it for SLO. That train normally left LA at 5 AM and was scheduled into SLO at 2:40 PM, though usually late.

(I learned a great deal from Mac. You can read major excerpts from my interviews with him across several posts; use “Gaddis” as the search term in the search box at the right. of this post.)

On my layout, empty cars nearly always come from Los Angeles, though occasionally from somewhere else on the division. It would be unlikely (though not impossible) for a car to arrive from another division, given the size and activity of Los Angeles.

Tony Thompson

Weathering the Rapido 1937 AAR box cars

I have posted two write-ups about the recently released HO scale models of the 1937 AAR box cars from Rapido. In the first of these, I showed the two Canadian box cars I received, and included photos of their prototypes (that post is at: https://modelingthesp.blogspot.com/2026/08/rapdios-new-1937-aar-box-cars.html ).

In a second post, I similarly showed the two U.S. box cars in my order, an Erie car and an SP car. Prototype details and lettering were shown there too. The post about them is here: https://modelingthesp.blogspot.com/2026/08/more-of-rapidos-new-1937-aar-box-cars.html . Both had some interesting paint scheme details, as explained there

Now these cars are all modified as needed (adding the Ureco handbrake to the SP car), as well as weathered and made ready for service. All had to receive reweigh and repacking stencils appropriate for my 1953 layout era. As usual, I relied on old Sunshine decal sets for these details. Lastly, I added raoute cards and a few chalk marks.

Here is the Canadian National car. I enjoyed the model’s having an NSC end and the integral ladder-sill steps, distinctively Canadian. 

The Canadian Pacific car was handled similarly to the CN one. It’s distinctive feature is the flat-panel roof, otherwise very generically 1937 AAR design. 

Next is the Erie car, which as I mentioned in the previous post about it, has an older paint scheme, with the black door. Accordingly I weathered it more heavily than some of these  cars. 

Lastly, the SP car, with its odd mixture of era paint features (as described previously). I decided to make it look as though just the SP initials of the factory lettering had been replaced with the post-1946 spelled out road name. 

I protected that road name with Tamiya masking tape, then applied my usual acrylic weathering to roof, ends and sides (see “Reference pages” linked at to right of this post). Removing the tape, a coat of flat finish was added to protect the weathering step. 

I then added paint patches for reweigh and repack stencils, along with new light weight and load limit numbers, all from Sunshine decals. To finish, I added chalk marks and route cards. The Ureco brake wheel is visible here.  

 Here is an  overall view of the left side of the car. 

This completes an interesting model of a hold-over Class B-50-18 original black roof, and replaces in my collection an upgraded Athearn “Blue Box” model of decades ago.

Tony Thompson 

Amazing use of my waybills

 Just the other day, a local modeler, Don Marenzi, let me know about something he had noticed in a YouTube video. It involved some of my layout’s waybills, in a peculiar context, as I’ll explain in this post.

The video is an interesting one, about the massive derailment and HAZMAT incident at Mississauga, Ontario in 1979. It  is at this link: https://www.youtube.com/watch?v=aJfFhMkwCkM . It uses TV, newsreel and press video and still photography, and describes the regulatory events that followed. In particular, the point is discussed that in 1979, first responders had no easy way to identify the cargoes of cars involved in a derailment.

In that discussion, some freight car waybills are briefly on the screen, at minute 21:37, as you see in the screen capture below. 

These, as readers of this blog will recognize, are waybills from my layout, which do happen to describe Canadian cars, but not only is neither one a tank car, one is even a refrigerator car. I have written a number of posts about cross-border traffic, and these waybills are from one of them, posted in 2020. You can see it at: https://modelingthesp.blogspot.com/2020/10/waybills-part-76-more-on-cross-border.html .

For clarity, I show below the waybill image from that post, clearly the original of the image shown above, though truncated top and bottom, and left edge of the pink one. Understandably, there is no credit to me or this blog

I have no idea why they chose non-tank car waybills, nor why they cut off the names of the issuing railroads (at several places in the video, they refer to CP cars as CN or vice versa, so they might not have been as clear on this point as one might wish). But probably they Googled “Canadian waybill” or some such, and used what they got. And it’s shown extremely briefly; many viewers would likely not even realize that those were waybills that went flashing past.

So perhaps, in Andy Warhol’s phrase, that is my “15 minutes of fame,” though sadly, it’s in fact only a small fraction of a second. I guess you have to take what comes along.

Tony Thompson 

My column in the September Model Railroad Hobbyist

My latest column in the “Getting Real” series in Model Railroad Hobbyist or MRH, a long-running series for which this is my 32nd column, has just appeared. My subject is one that, when considering possible topics for the next column, I was surprised to find I hadn’t ever written about before. The topic is how my Southern Pacific 1953 layout is operated.

I have, to be sure, described many details of layout operation, particularly my design and use of model waybills. But this is more of a 500-foot view of the events that make up an operating session.

An example is this photo of SP Consolidation 2829, making a switching move across Nipomo Street in Ballard. Just above it in the photo is one of SP’s converted 12-1 Pullman cars, now serving as a MOW bunk car, spotted on the Ballard outfit track (this project was described in an earlier post, at: https://modelingthesp.blogspot.com/2023/11/small-project-sp-boarding-bunk-car.html ).

Most of the article is taken up with describing the many Southern Pacific operating documents I collected or consulted. These range from the obvious, like Rulebooks, Timetables and Special Instructions for the Division I model, to less immediately recognized paper like a Brotherhood of Locomotive Engineers labor agreement, a schedule of manifest, merchandise, and perishable trains, or the “Locomotives Assigned” booklets issued quarterly by SP with divisional locomotive assignments. 

For example, here are two pages from that schedule of trains, showing at left the Coast Merchandise East or CME, familiarly known as the “Overnight,” and on the right, one of the “hot” through trains on Coast Division, the Los Angeles Manifest, symbol LA.  

A number of examples of various operating moments were included, partly to illustrate the layout, but more importantly to show the ways operating moves are carried out. One of those views showed SD&AE 103 switching at Santa Rosalia, picking up an empty tank car from the Richfield bulk oil dealer. The background of this locomotive, stationed at San Luis Obispo for years was the subject of an earlier blog post (you may view it at: https://modelingthesp.blogspot.com/2020/03/sd-locomotives-on-sp.html ). 

The photo above also shows several of the industries at Santa Rosalia, from the Coastal Citrus packing house at photo center, to the Channel Islands Kelp Products building just visible at right (see a summary of my construction article at: https://modelingthesp.blogspot.com/2022/07/my-article-in-july-2022-mrh.html ), and at rear, the Pismo Marine ship chandlers.

Another example that represents quite a bit of the switching work at Shumala is this view of SP switcher 1423 making up the second Santa Rosalia Local of the day. In the background, a Warren LPG tank car is at the LPG spot of the Associated Oil Company bulk oil dealer. Just above the locomotive is the caboose track, and at right center is the yard office.

I have tried in this article to both outline the operations of the layout, and to offer illustrations. In a similar way, layout history was encompassed in my article in the Layout Design Journal magazine (you can see a summary at: https://modelingthesp.blogspot.com/2026/06/my-article-in-new-layout-design-journal.html ). But a real article about the physical layout and its track plan remains to be done.

Tony Thompson  

Weathering big tank cars, Part 2

In the preceding post on this topic, I showed two 33,000-gallon LPG tank cars, in the form of HO scale cars by Tangent Models. These are to be weathered for a 1975 layout, making these cars about 10 years old. (The first post about these cars is at: https://modelingthesp.blogspot.com/2026/09/weathering-really-big-tank-cars.html .)

Just for a comparison, the 50-foot box cars I weathered earlier for the same layout are models of cars built only a few years before the layout era. Accordingly, they were only give a light overall haze of grime, as in this example.

I weathered the tank cars following my usual procedure (see “Reference pages” linked at top right) using washes of acrylic tube paints. I will begin by showing NATX 32141 (North American Car Corp.), leased to the Murphy Corporation, with a Spur logo. Murphy was a company operating a chain of retail gasoline stations, selling Spur gasoline, and also in the LPG market. 

I decided to weather the two sides a little differently. I wanted to show some streaking, and also some dirt discharge from below the valve bonnet. The first of these is the right side (following the usual rule, to stand at the B end looking at the car, and the right side is on your right). 

On the other side is more dirty streaking below the valve bonnet. Both sides have an overall dirtiness consistent with years in service.

The other car, NCTX 33019, is lettered as leased to the Canadian company Pacific 66, and lettered with the very large “LP GAS” lettering. The reporting mark belongs to North American Car (Canada) Limited. It is white and this color is always challenging to weather well. I decided to allow some “pooling” of dirt at low points. Here is the right side. 

I tried to get a little difference in the streaking and so on for the left side, along with dirt pooling along the lower curves of the tank. I also added some Pan Pastels to get the tone I wanted. 

These large cars are a different challenge from the freight cars I’m used to, and were interesting to deal with.

Tony Thompson 

 

Article in Dispatchers Office about BayRails

The October, 2026 issue of the magazine of the Operations SIG (OpSIG), The Dispatcher's Office or DO, has just been published. I show the cover below. I mention this issue because of an article in it that I wrote. But my authorship isn’t what’s significant about it.

What I want to call attention to is that the article, publicizing our local biannual operating weekend, BayRails (often mentioned here previously; to see more, use “BayRails” as the search term in the search box at right). The article states that, unlike many operating weekends around the country, BayRails is open to those who “don’t know somebody” and thus can’t get an invitation. 

Originally, I think, the invitation-only character of these events was to ensure that only serious people, who had some grasp of prototype operation, would be included. Nothing wrong with that goal, except it cuts out people not already acquainted with the “select” and thus with no way into these experiences. Giving people who would like to try operation, a chance to do so, seems like a good idea, even if they are people you don’t already know.

I showed five photos of Bay Area layouts in the article, chosen to be different from the ones used in a similar article I wrote in advance of the 2025 BayRails (DO, January 2025). Here is one the magazine didn’t use, a view on Robert Bowdidge’s HO scale SP Vasona Branch layout. In the photo, from left, Lawrence Crowl, Brooks Moses, Rich Murphy, and Bryan Borough prepare for a meet at Los Gatos on the upper level of the layout. It’s set in the 1930s.  

If you’re interested in BayRails next March, either as a possible attendee or just out of curiosity, I suggest you take a look at the website, which is at: http://bayrails.com/index.php . There you can find multiple photos of the other 15 layouts not shown in the DO article, along with textual information and layout histories. Dates are March 22–25.

If you’d like to know more about the OpSIG, there is considerable information at their website ( https://www.opsig.org/ ). Joining only costs $10 a year and includes four copies of the DO (electronic form), so a terrific bargain. Give it a look.

Tony Thompson