Weathering SP Steam Engines (Part 1)

This is going to be a quick update on some weathering techniques that I'm using on several different SP engines.  I'll first go over some of the various aspects of the weathering which will form the basis for weathering each engine in different ratios.

SP 2850 works a local with a stock car block.

Even lightly weathering models makes a huge difference when viewing them on a model railroad.  SP 2850, above, shows her light weathering on the La Mesa Club's Tehachapi Pass.

SP 3706, modeled as a clean and shining F-4 class 2-10-2, per prototype photos.

Only a very few engines should look as clean as SP 3706, which is being modeled fresh from shopping at Bakersfield in 1953, before she was allowed to become a leaking, filthy monster only a year or two later.

Basic Color Corrections

One of the most common issues I see with model steam engines is the driver centers (axles), pilot and trailing truck wheel faces, etc not being painted.  The siderods being bright "Chrome" is also not really correct for most "in-service" engines.  The shades of "Graphite" are also sometimes weird, requiring touch up, toning down, etc.  So I generally accept that I'll have to do this type of basic work before I can put an engine into service.

Out-of-the-box model with basic paint and finishing issues.

The driver centers and wheel faces are painted, as the prototype engines would be, then I usually tone down the bright areas of the rods.  I keep the crosshead guides as clean as possible, because that's one part of the real engines which is always shiny and polished from the crosshead sliding back and forth with every stroke of the piston.  The top and bottom edges of the guides (away from the crosshead) is painted black.  The rods on a cleaner engine are first painted a "natural steel" color, which I then add various levels of weathering over, discussed below.

The smokebox and firebox sides should be high-temp graphite.  Looking in photos this ranges in color from a light gunmetal color to a darker graphite color.  The real coating was made from oil and graphite, which was applied with a mop and baked on in service.  On the Santa Fe engines it went on silver and over the first 24-30 hours in service matured to a dark "Tarpon Gray" which seemed to have less silver aspect and more medium gray hue to it.  On the SP the coating seemed to stay more gunmetal metallic in hue.  After 1946 the SP applied Aluminum paint to the front of the smokebox for more visibility, and becomes a key indicator of the photograph's era.

I usually also paint the canvas sunshades gray or light beige and if the shop crews were being fancy some of the plumbing equipment: injectors, boiler check valves, cab window sashes, valve handles, etc can be painted Daylight Red.  I might decide to do that on a couple of engines, as the parts so painted become VERY VISIBLE.

Highlight Weathering

I should add here that some models, even though they're being modeled as 'clean' or passenger service should have some very light weathering, or highlighting on them to bring out the details on the model.

Many years ago I test ran the new IMRC AC-12s at LMRC without any weathering.   The straight black of the models and satin finish made them impossible to photograph because the model simply became a 'blackhole' in which no details could be seen.

SP 4202 leading "No 51", probably Second 51 in Soledad Canyon - Eddie Sims Collection

The model of SP 4202 that I finished as a 'freshly cleaned' excursion engine out of LA during the early 1950s meant that I didn't really want any noticeable weathering, per the prototype photos of the engine in Tom Dill's San Joaquin Valley book.  The photo above shows the train running as No.51, but I believe this excursion train was running as Second 51, with no flags, which would show "51" in the train indicators.  Note: First 51 that day would have been displaying Green Flags and "1-51" in the train indicators.

A clean and shining SP 4202 ready for excursion service.

However, if you look closely, the model has off-black coloring on the drivers and a few other places to make those details stand out.  The rods have been painted down from "Chrome" to a more natural oiled steel color.

The highlight weathering is also used as a finishing step after the other weathering effects are added, and to help blend the weathering together somewhat.  I find most engines, even lightly weathered need at least three applications and slight color changes to the weathering to get it looking like a steam engine in service, and not a toy that got hit with one "weathering color" and left.

Water Stains on Boilers

Probably one of the most distictive and obvious weathering features was the white and rusty boiler scale deposits streaking the sides of SP engines.

SP 3660 with heavy scaling on the outside of the boiler. Circa 1954 west of Bakersfield CA. Eddie Sims Collection.

The SP operated in many "bad water" districts with heavy amounts of alkali scaling and foaming contaminates.  This was treated by several methods, including water treatment balls added to the tender at each water filling in prescribed amount per thousand gallons taken at each stop.  There was also a system of infrastructure to soften the water in the most severe areas.  

Engines could start "Foaming" despite of these efforts.  This took the form of the water in the boiler reaching the point where it couldn't hold any more scale in solution, which begins frothing up, like a kettle of rice.  In extreme cases it could lead to the crownsheet being uncovered.  The crownsheet being exposed could result in the explosion of the boiler in at worst case scenario.  To prevent these dangers, the crew would try to blow down the boiler, using the pipes which exit the boiler around the mud-ring.  The crew would replace the water lost blowing down with water pumped into the boiler with the injectors.

The blowdowns were located at the front of the firebox mud-ring, at the lowest point in the boiler.  After about 1940, SP engines received distinctive mufflers and pipe extensions so that the possibly high pressure blow down emissions would be directed down towards the track and diffused to avoid injury to people and structures near the track.

Left side of SP 3682, with heavy scaling deposits on the boiler.

Right side of SP 3682, with some leaking at the check valve and also some staining behind the turbo generator.

Top view of the SP 3682's weathering.

Here's a couple other photos of boiler scaling.  Generally I've not been too impressed with most air brushed boiler stain weathering.  It can be done well, but I've done all of these effects with brush weathering.

SP 3634, an F-1 class 2-10-2 rests between trips. - Eddie Sims Collection

Mud, Grime, and Dust

One of the classic weathering effects, is that of the mud, grime, and dust that they accumulate while operating in arid environments of the southwestern US.  This can make different looks on engines.  One effect is mud from the blowdowns hitting the ballast or dirt and blowing back up onto the running gear.  This often stains the first driver or two closest to the blowdown, and also the trailing truck under the firebox (on AC-class engines this is the leading truck).

SP 4191 AC-8, running in the California-Nevada Desert on the Modoc Line - Eddie Sims Collection

The SP 4191 has an interesting mix of dust on the tender and drivers, soot on the smokebox and a white alkali scale streak leaking down out of the front end throttle.  The boiler shell is showing a variety of shades.  The low angle of the light in this photo's helping us see these subtle effects.

SP 2706 with heavy dirt stains on the pilot truck, pilot, cylinders and rear driver. - Eddie Sims Collection

Here's an example on SP 2706 of a smaller engine with pretty extreme mud and dirt accumulation.  It's good to check color photos of the division you're wanting to model to see the various shades that the weathering should be.

SP 2632 with 73-SC-tender and heavy weathering - Eddie Sims Collection

Here's a really cruddy example of an SP 2-8-0, obviously abused and under-cared for during the post-war transition time around June 1946.  We can see heavy stains on the cylinder block, the pilot, and the air compressor/firebox sides.  The drivers are highlighted along with the driver equalizing springs.  Soot streaks the front of the newly aluminum painted smoke box.  The tender however has not been repainted and had the "Lines" dropped.  Given that the engine is photographed sitting next to the water column, the tender might still be glossy from the water from the cistern overflowing and washing the sides clean, while the forward section is heavily streaked with grime and dirt.  

SP 3218 with some lower body mud and dust weathering. - Eddie Sims Collection

Here we see SP 3218 working around the Bay Area, probably in the southern area around San Jose, Oakland, and Watsonville Jct.  The engine has a coating of soot, as well as dirt and grime stains on the drivers, firebox, cylinders, and tender sides.

In terms of modeling these effects, I think the first engine that I did that really hit this effect well was the SP 2850.  Unfortunately, other than the photo at the top of this page, I don't have a good photo of it with lighting to show this coloring.  I'll show a few other models that show some of these effects.

SP 4279 works through Caliente with dusty stains on her running gear.

In the case of the SP 4279 and several other engines I've weathered, I've tried to match the dirt colors on the La Mesa Club model of Tehachapi Pass.  This for a while meant Polly Scale "Mud" but now that's been discontinued, I have been using mixes of Apple Barrel's "Territorial Beige" and "Lite Mocha" colors for these mud effects.

SP 3259 has the mud effect working around the pilot and trailing trucks, not as much on the drivers, per photos.

The SP 3259, shows some of the other effects of the roundhouse crews cleaning off the drivers somewhat when they could.  Also the rods and valvegear tends to stay darker and in some cases glossy because of the oils and greases used on them.  The SP 3259 shows a combination of these two effects.

SP 2850, stained by months of San Joaquin Valley Div operations works her way past the Carpentry Shop at Bakersfield.

SP 2850 has some subtle weathering which I'm pretty happy with.  The lower part of the engine has 'mud' stains and dust effects which matches almost perfectly with the colors of the LMRC's layout.  The combination makes the engine look like she's been working back and forth over the same areas since her last washing.

Stack Soot & Oil Grime

On the SP, soot weathering can cover a massive range of effects.  In the photo below, we see the SP 3271 heavily covered with oil grime and soot.  While the engine shows Train Indicators for No.783 working out of Bakersfield, the engine probably worked helper service over the Tehachapi tunnels recently and probably had a poor fireman that really "Smoked it up" during the trip.

SP 3271 working in the San Joaquin Valley, about to leave Bakersfield - Eddie Sims Collection

The oil fired engines could produce a plume of oily black particles that could coat equipment and the surrounding areas.  The crews tried to keep an "Econo-haze" in the stack.  This was a grayish color, mostly clear, showing that the oil was being burned most efficiently with the proper air mix.  The firemen had to work in time with the engineer to keep this optimum firing rate and clean stack.  Regularly when the engine had been sitting for a while, and they're working the engine hard, usually starting a large cut of cars, the fireman would "sand the flues" with about a cup of sand, fed through the peep-hole in the backhead of the engine.  The sand would scour the flues and blow all the accumulated carbon deposits out.  This is what is often seen in photos and movie clips being done, such as the video 'SP 1941', by Pentrex when the 1100-series 0-6-0 is working Mission Bay Yards and a great black plume erupts from the stack as the engine's pulling a large cut back to start switching.

In the book Baggage Car with Lace Curtains, the author, Bill talks about living and working in an ex-RPO-Baggage car inside the snowsheds at Norden, on Donner Pass.  He describes the black tar like "rain" that fell from the inside of the snow sheds as the snow melted off of them.  Also sometimes because the exhaust steam melted some of the snow on the sheds during the winter as well.  In any case, the workers had to wear rain coats in the sheds just to keep their clothes from being stained by the black water dripping on them.  In conditions such as that, it's little wonder that the SP's engines looked like the 3271 above.

Also I've seen a movie clip of the San Joaquin Daylight at Mojave, No.52, in which both Daylight-painted engines and most of the Daylight painted cars following them are thinly coated in a fine misting of black flecks from both GS-4s working hard up over the Tehachapi Pass's tunnels.  There's a reason they didn't regularly assign two Daylight painted engines to the train after 1951, and kept the Daylight painted one on the front!

SP 2400 rests between passenger assignments. - Eddie Sims Collection

More often the SP engines simply had soot over the high-temp graphite paint, as on the SP 2400 in the photo above.  Notice the soot shadow under the Train Indicator bracket, which results in a a clean streak.  Sometimes this really heavy soot coating comes from the engine working "steam oil" out of the cylinders and burning it as it slobbers out of the stack, rolling down the smokebox sides.  This could happen from over lubrication from the mechanical lubricators being incorrectly adjusted or coming out of the shop and having extra oil in the cylinders during the first fire-up.  The above photo of 2400 shows some additional weathering effects: probably some grime, dust, or grease on the running gear too.

Quirks of Weathering AC-Class Engines & Tenders

The AC's tenders sometimes had an interesting weathering pattern that showed up when the water was cold, and the air was humid.  Condensation would form below the water level in the tender.  As seen in the photo below, the sheen difference of the dry upper cistern side and the wet lower side.  Also notice that the oil bunker often is shinier because it is heated, allowing the oil to flow to the burner, and doesn't get the dust sticking to it.  The dirt however quickly clings to the condensation on the cistern sides, resulting in a dusty and dirty appearance.

The SP 4292 shows a common weathering condition on the tender in this photo. - Eddie Sims Collection

This is one of the things that is lost if you base your weathering on an engine which is 'dead' and not under steam.  Heat changes the sheen of the metal, the crew's care of the engines lubrication will look different than an out-of-service engine, and a 'dead' engine might have been weeks or months since it was last given a once-over with even 'running repairs' between trips.

Combining Techniques

SP 3738 on the Salt Lake Division with alkali and dust deposits on the boiler, drivers, FWH, and tender. - Eddie Sims Collection

Here's a heavily weathered example on SP 3738 in the pre-1946 era.  The engine is showing a combination of soot on the smoke box, a leak on the left check valve, boiler scale on the rear part of the boiler, also on the feed water heater (FWH).  The drivers and siderods are coated with dirt, scale deposits, etc.  The firebox, trailing truck, and tender is dusted with stains.

SP 3256 on the point with a MT-class engine behind. - Eddie Sims Collection

The SP 3256 shows a nice combination of soot on the smokebox, some sort of dark stain below the bell down the side of the boiler.  The lower area under the firebox and boiler is caked with dirt and grime.  The tender and boiler shell is highlighted generally and looks lighter than the MT class engine behind.  Notice this engine has a square cab still, like the SP 3259 above.

A New Project - SP 3266

SP 3237 and 3266 photographed at Searles Station with the excursion train in 1952. - Brian Black Collection

One of the newer projects I've been working on is a Balboa Mk-5/6 as the SP 3266, which was one of the few engines of this class that worked out of Mojave on local assignments.  Generally the smaller Mk-2/4s were assigned to these jobs.  The 3266 was the largest of the rated Mikados in the Employee Time Table for the Owenyo Branch out of Mojave, shown rated as far as Owenyo.  Most heavy steam was restricted past Inyokern.  The 3266 was photographed with the 3237 on a fan trip on May 30, 1952 to Searles and the Trona Rwy. by Carl Blaubach, Brian Black Collection.

SP 3266 sporting some desert dust weathering and some hard water stains.

There's also a lovely color photo showing the SP 3237 and 3266 at Mojave's engine servicing tracks in Tom Dill's San Joaquin Valley book, which was the inspiration to model this engine.

SP 3266's left side.

The 3266 is an easier modeling project now that the 120-C-6 tenders have been made available separately from Athearn-Genesis.  Most of the other details are the engine are close.  I'll be adding a new clam-shell stack and probably installing a road-switcher pilot on the engine later.

Athearn-Genesis SP 120-C-6 Tender painted and first coat of weathering applied.

 I've applied the first coat of drybrush weathering to the tender to match the engine, which was weathered about eight years ago using similar techniques.

Oil Bunker Weathering

SP 3266's 120-C-6 tender weathering

One of the things I've noticed in several prototype photos lately is the use of sand to absorb the spilled Bunker-C fuel oil on the decks of the tenders.  To model this, I weathered the top of the tender with dusting and dirt effects.  Then I put down some darker black paint to represent a spill.  Then some Lite Mocha applied with a brush using a stippling motion that was put down to represent the sand thrown around, sticking in the tar-like fuel oil.

Fixing Mistakes

One technique is to "over weather" an effect or color, such as the dusting effects on the curved upper tender cistern, resulting in a lighter color than is realistic.  To bring the weathering effect back, I used a wash of darker gray/black.  This should blend the effect into the unaffected areas better, if desired.  Sometimes a stark boundary between effects is desired.  Blowing the wash up under the upper walkway resulted in the wash also flowing down over the road name on the tender side.  One of the worst things that can happen when simulating water flow effects on a model, is to have it flow down the side of a carbody, but NOT be vertical!  These dark streaks are flowing sideways!

Here is some of my mistakes in letting the wash get down onto the lettering.

I didn't catch that the wash had streaked down onto the lettering until taking the photos.  Thankfully I had clear coated the tender after the decals were applied.  This seals the decals and allows the weathering work to be done "safely" over the top.  The acrylic paint wasn't fully hardened on, so I was able to carefully apply some 91% alcohol to try to soften the paint on the road name.  

Here's the fixed lettering after cleaning up the black on the lettering on SP 3266.

Gently moving the brush back and forth over the black paint on the underlying light gray letters, I was able to uncover them cleanly.  That covers the 3266 project for now.  The engine will have the smoke box dulled down and some soot weathering applied later. I'm sure I'll post something about that then.

In Closing

SP 2850 with weathered SP stock cars.

Hopefully this post will encourage more of us to do some light weathering on our steam engine models to match our weathered freight cars.  I find that light weathering is sometimes harder to do than heavy weathering and lighter also seems to be more realistic.  Also it has the advantage that if you want to increase the weathering later, which can be done without stripping and repainting the whole project.

Jason Hill

Related Links:

Busy Times in Bakersfield (Part 1) - Roundhouse Operations

Modeling SP Road Switchers (Part 1) - Small Steam

Modeling SP Road Switchers (Part 2) - Medium Steam

Modeling SP Road Engines (Part 3) - Heavy Steam

Modeling SP Road Engines (Part 4) - Articulated Engines

Modeling SP Road Engines (Part 5) - Passenger Steam