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Time to Model: Building My Custom MRL SD45

An Article by Trevor Sokolan

I’ve always been a fan of both the EMD SD45 locomotive and regional railway Montana Rail Link (reporting marks MRL), so with the release of the Scale trains SD45, I decided to model a unit from the railway’s early days. After finding a photograph of the MRL 6558 in patched out BN green taken by Brian Ambrose, I quickly ordered the HO version of the BN 6558 which Scale trains thoughtfully decided to produce.

The first step was to disassemble the model to allow for better access during the patching and weathering process. I removed the shell from the chassis, then separated the cab and sub-base from the long hood. I removed the long hood and cab side handrails from the model to allow for better access to the loco shell for weathering. I cut small sections of masking tape to cover the cab windows and lights to prevent hazing of the clear parts during the weathering process Using a generous amount of Walthers Solvaset and a pink pencil eraser I removed the Burlington Northern lettering from the sub-base as well as the BN logo from the cab sides. A small piece of masking tape was used to cover a section just below the cab windows where the MRL patched lettering was located on the prototype. I then masked off the cab and sub-base sides and sprayed Polly Scale BN Green to represent the area that was painted over to cover the original BN logos. The Polly Scale green is lighter than the factory green, which gives the illusion of a freshly painted patch.

The louver section just below the engineer’s front window was plated over on the prototype, so I cut a small square of 0.010 styrene painted primer red and glued it to the model.

 The front cab door on the prototype was replaced with a primer color door, so I masked the door on the model and sprayed some Polly Scale Zinc Oxide Primer. The factory windshield wipers were replaced with parts from A Line as I prefer the plastic versions. I replaced the factory air horn with a Details West part from the spare box as at some point the MRL added a 5-chime horn to the prototype. A pair of ACI labels from Microscale were added to each side as per prototype photos. After removing the small section of masking tape over the cab sides I brushed on some Future Floor Wax to the area, then once dried added the MRL lettering using a decal set from Microscale. 

To represent the faded BN green, I mixed some white paint with the Polly Scale BN green until the desired shade was created. I masked off the black running along the long hood and cab, then sprayed the green mix over the factory green in a few light coats. While the green was still tacky I removed the overspray from the road numbers and nose stripes. I lightly over-sprayed the long hood and cab handrails at the same time before re installing them onto the model.  After the green had dried overnight, I mixed some white paint into some black and repeated the process this time over-spraying the factory black on the model.

Moving to the chassis, I brushed a mix of brown paints onto each wheel face to cover the factory shine. I brush-painted Polly Scale Penn Central green onto the truck journal boxes to match the prototype photo, as well as painting the left front bearing housing red. The factory couplers were replaced with Kadee 158’s.

The entire model was sprayed with Future Floor wax, to provide a glossy surface to start the weathering with. I used Tamiya black panel line wash on all the hood doors and seams to give the areas more definition, a technique that I’ve become a big fan of. After applying the wash, waiting 15 minutes, then removing the excess with a Q tip dipped in thinner, I set the model aside to dry.

The next step was to spray the model with a coat of flat finish, which gives the model some “tooth” for the Pan Pastels to stick to. Using a variety of browns, blacks, and grey pastels I brushed pigment onto the model to match the prototype photos as best I could. I built up the weathering with several light layers of the pigments rather than one heavy layer, in order not to cake the material onto the model. When I was happy with the results, I sprayed everything with another coat of flat finish to seal in the pastels.

Once dry, I added some grease around the journal bearings and some fuel spills on the tank using Ammo by MiG Oil Stains wash. The prototype has some rust build up along the walkway sill and parts of the long hood, which I simulated by dabbing Burnt Umber artist oils onto the model with removing the excess with a small brush dipped in thinner. After the oils were added another final coat of flat finish was sprayed onto the model.

With the weathering complete, I removed the masking tape from the windows and lights and prepared the model to head into helper service on Mullan Pass (that last part takes a little imagination!).