Western Railroad Discussion > UP Yellow Paint Question

Perhaps it's been discussed before but in scanning some shots from my collection it really stood out. I have noticed it on units before but never gave it much thought. Here are 2 shots, taken on the NS in Atlanta Ga back in Dec 1993. While the date would put it into the Nostalgia relm, seeing it on some units since then, I thought it might get more answers here. Is there a difference in the yellow paint used in painting from shop to shop? The shot of UP B4144 shows what looks like a more orange tint to the yellow. It's an ex MOP nee CEI unit, 3144. The shot of the UP 3778 is a UP bought unit. It looks like a brighter yellow was used on this one. Did it depend on the shops doing the painting as to the difference in colors? Was it the "Pigment" that was different? Or something completely other than that? Was there something in the specs that called for differences? Just curious. Thanks, Ben

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The same unit B4144 appears in both photos.  I think the color difference is primarily due to lighting.
ALLEN



Edited 2 time(s). Last edit at 06/20/22 16:54 by krm152.

The overall white balance of both shots does appear to be pretty different, the picture of B 4144 looks like it's warmer, whereas the second shot as a much more bluish tint. If they were the same tint the paint shades would probably look a lot more similar.

UP definitely tried a number of different formulas for paints in the 1980s, with widely varying results; e.g., some SD40-2s painted during that time frame faded to an extremely light white-yellow color. Utahrails has some background on this, including on the federal regulations that prompted the changes in paint compounds, here: https://utahrails.net/up/up-diesel-paint-merger-era.php

All I'd add, and I think this is relevant to your question, is that the darker, orange-ish yellow on the ex-MOP SD40-2 in your picture was pretty common for a few classes of locomotives painted in the 1980s in particular: many of the C36-7s and SD50s, if you saw them running around years later (in the mid-90s) had faded to a shade similar to this, and some SD40-2s as well. Maybe the early, three-window SD60Ms of a few years later as well. So it's possible that as UP experimented with paint compounds in the 1980s they were using one for a while that faded in this way.

Hope that helps, maybe someone who knows more about these things can chime in. 

It all depended in the shop where it was painted and the manufacturer of the paint they had laying around.
They did come out in various shades.

Bob Krieger
Cheyenne, WY

The real reason was a requirement by OSHA /EPA for protective measures for workers applying, scraping, grinding or burning paint containing chromium and lead..  Lead chromate was widely used in paints. You might also have noticed changes in Cascade Green used by BN and the change in CAT yellow.  No doubt there were experiments with mixes by different paint suppliers.
RB

When Mike Root was painting his SD40s on the Comstock mine run he wanted the correct UP yellow. I called my buddy in UP
purchasing and we found there were 26 part numbers for UP yellow. These were all of a common color swatch and Dupont
color number so you could see that each shop was generating their own version.

Out 

I have noticed on the 5200 s (GE)  and up that the color had faded tremendously to a light shade of yellow. The EMD 3000 series are a brighter yellow that the rest of the fleet.  Bring back grey and scarlet !

My friend Mike Iden, now retired, worked for years in the CNW and later UP mechanical departments, offers this explanation for the paint issues:

<There are 2 issues, not related.  The first is “fading” due largely to exposure to ultraviolet (UV) light (from sunlight). Paints with organic pigments have tended to be more fade-resistant than those with non-organic pigments. But organic pigments have tended to be more expensive (ie, “paint cost”) and also affected by regulations over time (such as the withdrawal of yellow chromates that can become an issue particularly when paint is removed, such as by sand or grit blasting). 

<  The first 42 CNW Dash-8s came from Erie in 1989 and 1990 painted in the “Safety Yellow” (lighter than “traditional CNW yellow”) but quickly faded to a chalky-white. All 42 units spent their first 2+ years operating between South Morrill, NE and the SPRB mines, a relatively high altitude area. (Myles, NE, east of the CNW-BNSF junction at the south end of the SPRB Joint Line, is just over a mile high. The name was for a retired CNW VP, not a Myles to miles connection.) The as-built paint applied by Erie had inorganic yellow pigment and it didn’t weather well. All 42 units had their faded yellow replaced by Mid-America Car with “traditional CNW yellow” with a more durable pigment (still inorganic). Over time I too noticed that UP was getting various “slightly different” Armour Yellow colors from EMD and/or GE (and others) on new (and repainted) locomotives, and even Jenks repaints.
 
<Patricia LaBounty at the UP Museum loaned historic decades-old samples (carefully preserved paper-based “drift cards” of actual colors Yellow and Harbor Mist Gray and they were (carefully, “on loan”) sent to the builders and various paint manufacturers to perform computer scanning and color analysis, and “correct” their formulas. We found some not insignificant “color drift” had occurred over time as different paint sources were used, for example. In effect, the new process was a return of sorts to the “Common Standard” approach used during Harriman’s control of the UP and SP early in the 20th century. Ironically I found that the UP business car fleet had been doing the “right” thing (matching paint to the historic “drift cards”) for years …

<UP business cars were (and I presume still are) painted using historically accurate colors. And now new (and repainted) locomotives also.>

Thanks Mike!

JB - Omaha,



Edited 7 time(s). Last edit at 06/21/22 08:51 by Copy19.

up833 Wrote:
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> The real reason was a requirement by OSHA /EPA for
> protective measures for workers applying,
> scraping, grinding or burning paint containing
> chromium and lead..  Lead chromate was widely
> used in paints. You might also have noticed
> changes in Cascade Green used by BN and the change
> in CAT yellow.  No doubt there were experiments
> with mixes by different paint suppliers.
> RB

That is the answer to all the changes in various yellow paints. When I was promoted to the EMD Sales Engineering Dept. in the early 1970s, the Sales Engineer that handled the UP account, had his desk next to mine. When the federally mandated change to eliminate all lead in paint was enacted, my buddy had a hell of a time trying to explain to the Sales Manager that handled the UP account, in Omaha. The whole thing got so bad, that the UP Purchasing Dept. claimed that THEY would purchase the CORRECT Armor Yellow them selves, and have it shipped to EMD! Obviously even the "Great and Powerful UP" was unable to get ANY paint manufacturer to re-produce their famous Armor Yellow, without lead.  Thus, subsequent orders of EMD units for the UP, shipped with the "new" yellow.

With the white balance issues of various pictures and the known variations in actual units owing to different paint formulas, I would not be surprised if any two units were the same exact shade absent retouching to make them look the same, and even in actual life I think there would be subtle to marked differences in what you see there!

It's the light and or film.

Please forgive my ignorance but what does the B stand for on the 4144?
Is it simply a B unit?

Here's what 3778 looks like when the color balance of the scene is shifted to match the balance in the shot of B4144:

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bankshotone Wrote:
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> Please forgive my ignorance but what does the B
> stand for on the 4144?
> Is it simply a B unit?

Yes, B unit there are engineer controls and 1 seat in there but thats it. UP did this in the late 90's to some ex MP dash-2's.
JC

Posted from Android

Compare the shades of the tree leaves -- very similar 'change'.........

SZ

bankshotone Wrote:
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> Please forgive my ignorance but what does the B
> stand for on the 4144?
> Is it simply a B unit?

Long answer, YES.  The UP decided in the 80's, maybe 90's, to turn a bunch of SD40-2's into B units to lessen maintenance.  While the majority of these engines were ex-MOP, several actual UP units with dynamic brakes got the same treatment.  Don Strack's Utah Rails site has the complete details.  

Nick Tharalson,
Marion, IA



Edited 1 time(s). Last edit at 06/22/22 19:22 by ntharalson.

Evan_Werkema Wrote:
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> Here's what 3778 looks like when the color balance
> of the scene is shifted to match the balance in
> the shot of B4144:
Thanks Evan, I still see a difference in the shades. The B4144 still to me has a more "Orange-ish" tint, darker perhaps. Ben

bankshotone Wrote:
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> Please forgive my ignorance but what does the B
> stand for on the 4144?
> Is it simply a B unit?

The unit can be trailing in the consist but not used as the controlling unit.

Posted from Android

Glad this topic came up. I have selected a yellow and red from automotive epoxy paints due to the metal being galvanized. I'm sure the basis of what film was used in a camera, you could get a variance of spectrum of yellow. I will be lettering it this week and painting the undercarriage in a couple of weeks.  

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