Step-by-step guide on repainting a locomotive. GP40-2 from CSX to Southern Pacific.

Repainting a locomotive can be a fun and rewarding project. I got a couple of N scale Atlas GP40-2 locomotives painted and lettered for CSX off eBay. They were reasonably priced, and I wanted to repaint and letter them in Southern Pacific Railroad’s “Bloody Nose” paint scheme, so I bought both to use them on my N scale layout.

Before proceeding with the repaint, I wanted to make sure I could replace the factory-installed Rapido couplers with Micro-Trains. It turned out to be an easy upgrade.

Disassembling

Before repainting a locomotive, it’s best to remove the old paint completely. I began by detaching the shell from the chassis and disassembling all its parts before soaking them in 99% isopropyl alcohol.

I carefully removed all clear plastic components, such as the headlights and windows. Additionally, I disassembled the trucks, as I plan to repaint them SP Gray.

Now, all the parts are fully disassembled and ready for paint stripping.

Paint stripping

I submerged all the disassembled parts in 99% isopropyl alcohol, using a glass jar with a sealing lid to prevent evaporation

After 24 hours, I used a soft toothbrush to carefully remove all the softened paint. I paid particular attention to the delicate handrails to avoid damaging them while ensuring the paint was completely removed.

Repainting the locomotive parts

I then painted the nose and tail with SP Scarlet with an unopened bottle of Polly Scale paint that has lasted through the years – I purchased it in 2006! A a backup bottle of Vallejo Red RLM23 (71.003) was available, which can be used as a substitute for the discontinued Polly Scale color.

I prefer SP Scarlet from Polly Scale over Vallejo Red, as it should match the red “wings” on the Microscale decals.

After masking the nose and tail, I painted the rest of the locomotive in SP Lark Dark Gray. I had a couple of Polly Scale SP Lark Dark Gray bottles from mid 2000s, but neither aged well. So I opted for Vallejo Engine Gray (71.048), which is a very close match.

I also painted the disassembled trucks and fuel tanks. After letting everything dry, I removed the Tamiya 6mm masking tape.

And here are the two GP40-2 locomotives, ready for a coat of clear gloss varnish before applying the lettering.

Detailing

Before finalizing the painting, I added a few details to the locomotives: cab sunshades and snow plows. I purchased them from Trainworx.

I used a hand drill with micro drill bits to carefully make holes in the cab for the sunshades.

Then I installed the sunshades, securing them with a tiny drop of Tamiya Multipurpose Cement (Clear) glue.

After the glue has dried, I painted the sunshades with the same Vallejo Engine Gray color.

I then added a Trainworx snow plow. Using a sharp hobby knife, I trimmed a small piece of plastic from the locomotive’s front to fit the plow.

Then, using a hand drill and a fine drill bit, I drilled two small holes.

I used Tamiya Multipurpose Cement (Clear) glue to secure the snow plow in place.

Lettering

Using Microscale decals, I completed the GP40-2 lettering after repainting the locomotives. I chose to model units 7240 and 7609.

The red wings on the nose are always a bit tricky to apply, but I managed to get through it.

Weathering

I then applied a weathering coat by washing the grills and adjacent areas with black India ink, followed by airbrushing a couple of layers of Polly Scale Depot Buff (70/30 thinner-to-paint mix).

The Depot Buff (light tan color) replicates a layer of accumulated dust.

Here is the final result. Southern Pacific GP40-2 7609 and Southern Pacific GP40-2 7240, both equipped with a Zimo MX615 DCC decoder.

Step-by-step on painting freight cars in batches with airbrush and acrylic colors

Painting freight cars: I recently purchased a few inexpensive, older Roundhouse boxcars and Athearn mechanical reefers on eBay to repaint and letter for the Southern Pacific Railroad and Southern Pacific Fruit Express.

For this project, I used the discontinued Polly Scale Boxcar Red – yes, I still have a bottle from 2007 – along with Vallejo acrylic paints. Unfortunately, the Polly Scale paint had aged poorly and clogged the airbrush, regardless of how much I thinned it.

Boxcar Red color with Vallejo acrylic paint

To achieve a convincing “Boxcar Red” color, I mixed equal parts of Vallejo Camouflage Medium Brown (71.038) and Vallejo Brown RLM26 (71.105).

Painting freight cars in batches

I prefer to paint in batches to make the most of my effort.

This time, I prepared three 2-bay covered hoppers, four boxcars, three 57′ mechanical reefers (to be painted and lettered for SPFE – Southern Pacific Fruit Express), and one old, inexpensive caboose.

57′ Mechanical Reefers

Soaking the boxcar shell in 99% isopropyl alcohol for at least three days significantly simplifies the paint removal process. As shown above, the paint practically lifts off the shell!

I washed the car with warm water and a drop of soap to remove fingerprints or oils, wearing plastic gloves. I used a soft toothbrush.

Once completely dry, I sprayed a coat of Vallejo acrylic White Primer using an airbrush. I used a few drops of the Vallejo Flow Improver.

After painting the roof white (Vallejo White 71.001), I masked it off and sprayed the reefer with Vallejo Orange (71.083).

Then I carefully and slowly removed the masking tape

Here is future SPFE 459273.

Two other 57′ SPFE Reefers will be painted with black ends. I properly masked the car and sprayed some Tamiya XF-1 black thinned 3:2 with Vallejo Airbrush Thinner.

This time I experimented with a few drops of Vallejo Airbrush Flow Improver.

Reefers are now ready for a coat of gloss varnish. This layer provides a smooth surface for easier decal application, helping the waterslide decals adhere properly without silvering.

Lettering (applying waterslide decals)

To apply the decals, I first cut them out carefully, staying close to the printed edges for a clean finish.

I soaked the decals in warm water for 10–15 seconds, just enough to loosen them from the backing paper without over-soaking. I gently slid the decal onto the car, positioning it with a soft brush or tweezers.

For tricky areas, I used Microscale Micro Set decal-setting solution to help the decal conform to surface details like rivets or panel lines. For the most difficult irregular surfaces I used Microscale Micro Sol, to soften the decals for a few seconds before applying them.

Once positioned, I lightly dabbed with a cotton swab or soft cloth to remove excess water and ensure the decal sits flush.

I allowed the decals to dry completely before applying a final coat of clear matte to seal and protect them.

After the flat clear coat dried, I proceeded with installing Micro Trains Line 1015 body-mount couplers. I drilled a hole in the metal chassis e screwed the couplers down.

Painting undecorated cars can be a daunting task, requiring skills like airbrushing and decaling. However, finding a cheap undecorated car to experiment with and refine these techniques is fairly easy.

Moreover, if you have a decorated car that you never liked, it could be a good candidate for this project.