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RUSTALL REVIEW
by Thomas Knapp


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by Thomas Knapp, MMR #101

rust (rŭst) Any of various powdery or scaly reddish-brown or reddish-yellow hydrated ferric oxides formed on iron and iron-containing materials by low-temperature oxidation in the presence of water.


  1. Any of various metallic coatings, especially oxides, formed by corrosion.
  2. A stain or coating resembling iron rust.

E
xcept for brand new (like in…today…) or freshly back-shopped equipment, virtually all railway equipment has some rust, dirt and other deposits on it resulting from use and exposure to the elements. Railroad equipment manufacturers, owners and operators all try to prevent this, with varying levels of effort and with varying degrees of success.odel railroaders call it “weathering” and love it!

Locomotive

When weathering equipment, it is important to understand the cause of the weathering, and the direction from whence it comes. Soot on locomotive skylines and roofs emanates from stacks, settles down on top of horizontal surfaces, and its area of accumulation extends back along the equipment by virtue of the
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equipment’s generally forward motion. Calcium and other contaminants borne by feed water or steam generally flow down from the source as the steam condenses on the outer surface of the metal jacket of domes, cylinders and pumps. Metal surfaces that experience high heat cycles which burn off paint or other surface protection, such as smokeboxes, fireboxes and firebox stay bolts will have surface rust. Water may tend to accumulate at seams and joints in horizontal metal surfaces, such as around water hatches on tenders or on side tanks, with resulting rust. Riveted joints in water tanks will often show rust deposits around the head of the rivet either from the accumulation of external water, or from seeping at the rivet. Lubricating oils and grease – although not “weathering” - will leave deposits – sometimes shiny – on metal surfaces. Dirt thrown up by the movement of equipment through the environment will accumulate on running gear and sometimes the lower sides of equipment. Freight equipment is not only subject to many of these same weathering impacts, but also the materials they are subject to handling, or processes associated with those materials, from the lye used to sanitize stock cars, to coal dust, to … well… you get the idea. Another condition which is lumped into “weathering” is the fading and oxidation of painted surfaces due to sunlight and exposure to the air. (See sidebar.)

Speaking of oxidation, back to the main subject of this article – RUST. To paraphrase a definition from Wikipedia:


“Rust is a general term for a series of iron oxides. Colloquially, the term is applied to red oxides, formed by the reaction of iron and oxygen in the presence of water or air moisture. ... Rust consists of hydrated iron oxides Fe2O3·nH2O and iron oxide-hydroxide (FeO(OH), Fe(OH)3). ... Given sufficient time, oxygen, and water, any iron mass eventually converts entirely to rust and disintegrates.”


Now, we usually don’t want our model railway equipment to disintegrate, but, we do want to try and realistically capture the look of rust – whether it is minor and incidental rust on an otherwise well-maintained piece of equipment, or that terminal rust that is the precursor to the eventual disintegration of wrecked and abandoned metal junk. Modelers creatively portray rust using several methods. Not all methods “scale down” successfully to N-scale. Techniques such as dry-brushing with rust-colored paints, besides being one of the less “controllable” techniques, tends to hit the high portions of model surfaces, such as the tops of rivets, etc. Chalks have the same problem, although they are more controlled and can be worked down to settle into recesses. However, the best method I have found to duplicate rust, from minor to major, is a liquid product called RUSTALL. ( www.rustall.com ) This product
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comes in a four-part kit, and can be applied to anything – metal, styrene, wood, paper, your fingers (although the later is not recommended by the author) – and will produce a realistic and finely grained or coarse and crumbly rust texture. (A major model supply company has recently come out with a “copy-cat” product, which I have tried and discarded – in my opinion the color and consistency of the “rust” is not as good as the original.) The key component of the four parts is a “rust” solution which is thin and fluid, and is applied in layers, building up the rust to the level desired. It flows readily across a model surface and collects around the edges of rivets, in seams, and at abrupt changes in panels – in the same way water would collect on metal and gradually oxidize the metal into rust. The kit also includes a black solution which can be applied to surfaces to collect in recesses in much the same way and bring out detail. The third part of the kit is a “dead flat” sealer coat, and the fourth part is an optional very finely ground dirt with some clay in it which can be dusted onto surfaces to... well ... represent “dirt.” It also can be used in combination with the other parts to create very coarse, crumbly rust effects in larger scales, although with care you can also use it this way in N, as will be seen in a couple of examples in this article. If you use one of the components up, replacements bottle of each of the individual components are available.

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The instructions (both printed and on-line) described the simple four-step process: slosh on the rust solution (#1); when dry, apply a coat of the back solution (#2); seal with a coat of “dead flat” (#3); dust with dirt (#4). It is pretty fool-proof. The unique property of these components which sets them apart from
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other ways of simulating rust is the controllability of results. Solutions #1 and #2 deposit small, thin layers of their rusting and blackening ingredients, allowing the modeler to control the degree and location of rusting. Also, if you don’t like the result, you can easily remove it with alcohol. For this article, I have prepared examples representing degrees from very minor rust deposits which might be found on well maintained equipment, to significant rust on still-in-service equipment, to crumbly, flaking rust on scrap or abandoned equipment. The step-by-step photo examples are supplemented by vignettes of completed models illustrating the modeling of different rust effects.

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I selected a variety of metal castings of industrial equipment as an example of how to “rust” old equipment. (Photo 1) I mounted these castings on a plastic card using
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double-stick tape, then gave all a base coat of Floquil Weathered Black (see sidebar.) Before the undercoat dried, the single-cylinder horizontal steam engine and one of the modern boiler fronts were given a sprinkling of the dirt in #4, while the sides of the air compressor tank received a very fine dusting of #4. When the undercoat had dried, the castings were then given multiple coats of solution #1. (Photo 2) When I was satisfied with the amount of “rust” on the parts, I applied the blackening solution #2. The results of the “rusting” are show in the group portrait (Photo 3.) The different effects are clearly seen in the comparison of the lathe (Photo 4) or the Erie steam hammer (Photo 5), which have surface rust to the flaking scale on the air compressor tank (Photo 6). This is also clear in the two different effects represented on the modern gas boiler fronts (Photo 7) one of which represents a recently rusted, perhaps still functioning boiler, the other which is clearly beyond redemption. The rust deposits and blackener can also work on painted parts such as the three red oil drums. (Photo 8) For the 18” gauge ore car in Photo 9, I applied an additional thinned coat of Weathered Black to the inside of the car after rusting, and sprinkled more #4 inside.

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Most of my railway equipment is weathered to represent well used, aging – sometimes second hand as in the case of a lot of Pacific Coast Railway equipment – but still
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roadworthy equipment. Photo 10 shows typical rust deposits on the top of a tender where excess water from filling the tender has accumulated and caused minor surface rust. The side tank on the 0-6-0T in Photo 11 has minor rust around the heads of the tank rivets, and on the top of the tank at the filler. Both of these represent a single application of RUSTALL solution #1. Contrast this with the saddle tank 0-6-0T in Photo 12, which represents a roughly treated locomotive. Two areas where even well-maintained steam locomotives with any service time will show rust are the smokebox and firebox. The smokebox in Photo 13 is an example of surface rust on the smokebox of an in-service well weathered (but not derelict) road engine. Likewise, Photo 14 shows the firebox of an in-service K-28.

As a non-steam example, the narrow gauge center cab diesel in the Photo 15 was weathered to represent an industrial or contractor-owned switcher which is showing its age, but is still a serviceable workhorse. In this case, the rust deposits represent surface rust on painted sheet metal. Light applications were allowed to gather at the edges of surfaces and in recesses such as louvers and the edges of access doors.

Modern railway equipment is perhaps even more subject to a lack of cosmetic maintenance than period equipment (or perhaps it is modern color schemes show more than vintage schemes?) Whether it is because equipment strays so far from home in modern interchange, or the simple realities of life-cycle-cost-analysis on maintenance programs, a lot of modern freight rolling stock looks “old before its years.” Not having any modern standard gauge equipment, I bought a Red Caboose FMC covered hopper lettered for Cook Industries for this how-to example, although
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not an ideal candidate, as it is not painted, but raw plastic molded in the finish colors. Photos 16 and 17 show the car and trucks before applying the RUSTALL weathering regime. The first step is to slosh on some of solution #1 (Photo 18) on one side at a time to control the direction the solution flows. Move on to another face only after the one you just did dries. Since this is intended to represent a car in active interchange service, one application on each face was all that was necessary. (Compare Photo 17 to Photo 19.) The undersides of railway cars accumulate dirt, mud, oils and grease thrown up from the track and thrown off by lubricated components such as trucks. They quickly lose any semblance of the upper surfaces colors. I gave the bottom of the hopper a coat of Floquil “Foundation” to tone down the “baby blue” of the molded plastic, and to provide a base for the weathering. To this I applied a coat of rust solution #1. (Photo 20) After the “rust” was dry, I applied a coat of “dead flat” #3. (Photo 21) When this first coat was dry, I applied a second, and – while still wet – sprinkled the wet surfaces with dirt from bottle #4 using a brush to transfer the material and spread it around. (Photo 22) The result was a floor crusted with dust and dirt, with rust showing through here and there. (Photo 23) I gave the trucks a coat of Master Modeler Burnt Umber (Photo 24), then followed with rust solution #1 (Photo 25) and black solution #3, which settled in recesses and brought out the details (Photo 26). The top of the car received washes of solutions #1 and #2 as well. (Photo 27) Compare the completed car (Photo 28) with the out-of-the-box car (Photo 16) and the detail of the end (Photo 29) with the as-bought end (Photo 17). I think the completed model looks quite realistic in a layout setting. (Photo 30) Rust is not confined to the cars themselves – sometimes the contents have rusted, as in the scrap metal load in Photo.

I have also used RUSTALL on road vehicles and structures. The pickup on the left in Photo 32 is badly rusted, with flaky chunks of rust on the surface, while the flatbed in the back has only trace amounts of rust. The fuel oil tank in Photo 33 shows rust at the riveted seams in the metal tank. And the cast resin scrap pile in Photo 34 was prepared the same way as the industrial equipment castings at the start of this article. Finally, ending this diatribe on rust, Photo 35 combines rusted corrugated iron siding, a rusty mining ore car, and a venerable 0-6-0T, all weathered with RUSTALL.

SIDEBAR

“Aging” versus “Weathering”
While Ithink the semantics could be debated, the real distinction here is a “real world” difference between the degradation of a surface such as happens with rust, blistering and peeling paint, oxidation of painted surfaces, splintering and graining of wood, etc. and the obscuring of a surface due to build up of other materials such as mud, dirt, grease, etc. on the surface of the base material. As modelers, we may use techniques of applying something to the top of a surface to simulate the degradation of the base surface, but need to be aware of this real world distinction. Even relatively clean surfaces will degrade with age and exposure to pollutants in the air and to the fading effects of sunlight.

Before applying surface weathering the base surface should be prepared to represent the “baseline” material condition. Steam locomotives were commonly painted black. Observation of builders’ photos of new equipment will show crisp, shiny
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black coats of paint. They will also show these shiny, black painted locos actually will reflect sky colors, tending to mute the black to shades of gray, especially on upper surfaces. Besides being unrealistic, in a typical train room or train show setting, details on locomotives painted “Engine Black” tend to get lost. There are two schools of thought on “black” locomotives. One starts with Floquil Engine Black, then follows with an airbrush coat of Floquil Weathered Black, then very light dry-brush application of light gray to high-light top, reflective, surfaces. This has been the typical way of modeling an oxidized black paint finish in most scales for decades. Many N scale modelers follow this proven method. However, on kit and scratch-built locomotives which I know I will want to represent as weathered, I usually start by airbrushing the entire locomotive Floquil Weathered Black and skip the “undercoat” of Engine Black, then move on to dry brush for “high lights” and then the application of weathering. For miscellaneous ironmongery you are weathering and rusting, give it a base coat of Floquil Weathered Black of Humbrol No. 76 before commencing the “rusting” process. . For factory painted equipment, with light “aging” effects, you may need to do nothing. For equipment that has several years’ exposure to the elements, one of the most visible effects will be on lettering and on dark painted surfaces. There are a variety of ways of “toning down” colors and lettering/graphics. One is carefully dry-brushing or light air brushing with the background color. Another is to abrade the surface with something such as a fiberglass scratch brush. (All the locomotive lettering in the accompanying photos was “aged” using dry brushing of the background color over the lettering and numbers.)



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