The Pennsylvania Railroad was an early proponent of standardised colors and paint schemes for its locomotives, rolling stock and other equipment.
Pennsylvania Railroad locomotives were uniformly painted in a color commonly called Brunswick Green but known to the railroad as Dark Green Locomotive Enamel (DGLE, or DGLC for -Color.) This was an effectively black paint that contained a high proportion of copper oxides. These gave it a very slight greenish tinge that became more pronounced over time and with wear as the paint oxidised. DGLE is often described as being indistinguishable from black when fresh unless next to a pure black paint (as used on the underframes of PRR locomotives beneath the running boards).
PRR steam locomotives bore PENNSYLVANIA on their tenders and their numbers on the cab sides; diesel and electric locomotives had PENNSYLVANIA centrally and numbers closer to the ends. The typeface for the railroad's name was traditionally Craw Clarendon but there was a brief flirtation with Futura in the 1930s advocated by the PRR's favorite designer Raymond Loewy. Freight locomotives were lettered in Buff, a light yellow, but passenger locomotives were lettered in true gold leaf; this practice ceased in the late 1940s and thenceforth all locomotives were lettered in Buff.
Loewy prescribed the use of five pin-stripes down the middle of the PRR's new GG1 electric locomotives, tapering down at each end; these pinstripes were initially gold leaf to match the lettering, and changed to Buff when the lettering did. These pinstripes were also worn by passenger diesel locomotives. Many freight diesel and electric locomotives wore a single, somewhat thicker stripe in the same place. Later on, a single even thicker stripe replaced the five pinstripes for easier painting; this was accompanied by much larger PENNSYLVANIA lettering.
Passenger cars were almost without exception painted in Tuscan, a brick-red shade, with gold leaf or later Buff lettering and striping. A number of other railroads used this shade or similar.
In the 1950s, the PRR experimented with painting a few of its GG1 electric locomotives in Tuscan to match the passenger cars. Most GG1s continued in DGLE, but the PRR did adopt this livery for passenger diesel locomotives; most were soon repainted in Tuscan. These locomotives also bore five Buff stripes and followed the same history of being repainted with single broader stripes and bigger lettering/keystones.
A very few passenger cars were left in natural stainless-steel; unlike most railroads, the PRR generally painted its stainless-steel cars.
Freight cars were painted in 'Freight Car Color' (FCC), an oxide red. This was historically a brighter red than that used by most American railroads although it became a more standard shade from the 1950s. They bore an underlined 'PENNSYLVANIA' until the 1950s; from that point they bore a large Keystone herald also.
PRR work equipment was painted battleship grey until the 1950s when a bright yellow replaced it. Wreck derricks were painted black, however.
Towers (signal boxes) were generally painted a light grey, as were most other buildings.