Here is my take on boxcar colors using Pollyscale paint. That is my standard so I can't help with the other brands. I have painted with all but most of the time simply mixed my own. I'm not claiming these are exact matches for what you see. We all perceive colors differently. Now with that said:
Go to my web site and more information can be found as to the dates these "colors" were used.
Freight Car Brown-(Pollyscale #414281 "Boxcar Red") Using pictures, I add in very small quantities, some black or white to darken or lighten. Often a straight application works, then with the added weathering you can come closer to the picture. Also a good color on early Southern cabooses.
Freight Car Red-(Pollyscale #414352 "Lt. Freight Car Red") This is a bit redder than the Freight Car Brown. Use same technique as above although adding white can result in a pink color. Also a good color for the Southern cabooses between the early brown and the later bright reds.
Caboose Red-(Pollyscale #414128 "Caboose Red") This is a bright red used on many cabooses but not on boxcars.
Mineral Red-(Pollyscale #414350 Mineral Red) A bit darker than caboose red, used on boxcars from the early era(pre)1950's.
Oxide Red-(Pollyscale #414354 Oxide Red) Between boxcar red and Lt. freight car red. Is a good color for cars that have weathered darker. A lot like red lead primer seen on steel bwefore it is painted with a final color.
Car Cement-(Pollyscale #414110 Engine Black)What can I say....Some like Grimy Black(Pollyscale #414137) which has a more grayish tint or faded look.
It is very difficult to describe colors and even harder to show them on the web or in a book, still the best course is to look at the photo of what you are painting and try to match the best you can. You can always resort to heavy weathering if matching the paint fails..... :)
Maybe others can comment on other brands.
TYPICAL FREIGHTCARS DOORS 1950-70
CLEAN FREIGHT CARS 1950-70
notes from Freight Car talk-list08/24/01 FC list In the "classic" era (ca. 1940s-50s) some boxcars were designated for high-class ladings, such as grains or foodstuffs. Others were labeled for foul cargoes, such as hides. Were there standard AAR designations, such as "class A" or the like? If, so what were they? Any idea of what proportion of the fleet fell into the various categories? In what way could a shipper know that a car offered by the RR was suitable for their lading? How did the RR know? This information would be helpful for planning and for better understanding of freight car utilization. David Soderblom 08/24/01 FC-list Railroads still do classify boxcars as "A", "B", "C", and "K" for loading purposes. This classification is not found in the Equipment Registers, printed or computer, as railroad car inspectors and damage prevention officers can and do change the classification. I car might get a "dirty" load and be downgraded, while one might come off a cleanout track upgraded, especially of minor repairs were also performed. Once a car is classed as "K" for contaminated it cannot be upgraded without rebuilding. Loads such as hides or carbon black will earn a car a "K" rating. For example, roll paper must be loaded in a Class "A" or "B" car, put don't tell the paper shippers that, they will insist on a Class "A", which is for packaged freight. Each railroad's car distribution system maintains the grades, which are exchanged between carriers when cars are interchanged. Gregg Mahlkov 08/24/01 FC list You've just opened about the biggest 'can of worms' in railroad car utilization. When I was first involved with car utilization in 1963 it was a problem that had been around for a long time and when I was last involved in 1982 the state of dealing with car suitability classification was about as chaotic as it was in the 50's. I'm going to leave this open on my desk top and add random notes as they occur to me. There was no AAR standard, but the basic system was that a class A car was tight enough for grain loading, a class B car was good for clean loading, and class C was anything else. Railroads tried to limit loadings of hides and lampblack to designated cars, but good cars did leak into that service. Getting cars classified and transmitting the information was a big problem. It costs money to have a car inspector open a car door, write down its condition and give that to a yard clerk or station agent. To the operating line manager responsible for the inspectors and clerks, that was pure expense and they got no credit for the revenue. The AAR car utilization task force of the late 70's identified classification as significant problem and spent money trying to define and solve it, but I don't recall that they ever came up with a system that was generally accepted. You couldn't really designate cars for grain or foodstuffs because under car service rules they were general service cars available for any suitable lading. Some railroads tried, but such a policy was unenforceable. Before the days of computers there was no way to catch the violators. Some railroads had a car condition code in their computer systems, but having it used effectively was problematic .. see above comment about cost of clerks and car inspectors. Malcolm Laughlin 08/27/01 The AAR Freight Claim & Damage Prevention Division published numerous "Loading Pamphlets" for various commodities loaded in closed cars and TOFC trailers. These will usually start with what grade of car should be used. While not technically "mandatory", failure to follow the suggestions will compromise the validity of a loss and damage claim. There used to be literally hundreds of different pamphlets. As far as the "K", the word "contaminated" begins with a hard "C", which sounds the same as "K", and since "C" is already a grade................... This grade is strongly enforced, as the wrong freight in a contaminated car can result in a large freight claim. Gregg Mahlkov 08/27/01 A follow up question: Is there a document that lists the fact that roll paper should be in an A or B class car? Dave Soderblom 08/28/01 As of 1955, the AAR's designations for box cars were: Class A ~ Flour, Sugar, Meal, Cereals in Packages, Food and similar products. Class B ~ Cement, Lime, Plaster, Dry Goods, Notions, Broom Corn, Hay, Seeds (Boxed or Sacked), Furniture, Finished Lumber and Millwork, Iron (Sheet and Wire), Bailing and Ties Castings, Tin Plate, Salt (Bulk and Packages). Class C ~ Bulk Grain and all other Bulk Freight liable to loss through openings in cars. Class D ~ Merchandise and all other car load freight not included in classes A, B, or C except rough freight. Note, cars which do not meet the requirements of Classes A, B, C, or D will be carded for rough freight. The above classifications were accompanied by the descriptions for the various conditions of cars which met the commodity ratings. These are a bit lengthy, but I could summarize if it might help. Guy Wilber