These are the paint schemes applied to the GG1 over the course of the Pennsy. The green was actually darker, but is shown light here in order to contrast with black.
Early Prototype Scheme
1934 PRR: Dark Green, block pinstriping, small number keystone
1934: 4899/4800 only. (unit changed numbers in this scheme)
Developed by the PRR, this scheme predates the Loewy design. A similar design was used on the R1 experimental.
Late Prototype Scheme
1935 PRR: Dark Green, Wide 5 gold pinstripes and gold sans-serif Futura lettering, small number keystone
4800 only, through at least 1937
First to be based on the Loewy design, but would later be refined on production units.
1935 PRR: Dark Green, 5 gold pinstripes and gold sans-serif Futura lettering, small number keystone
All units at production except 4800, 4800 sometime after 1937.
The scheme as Loewy envisioned it.
1937 PRR: Dark Green, 5 gold pinstripes feathered together and gold sans-serif Futura lettering, small number keystone
4829 is only confirmed unit.
This may have been and experimental variation to try to avoid the problems of painting over the intake vents on the locomotive's sides.
Modified Loewy Scheme
1941 PRR: Dark Green, 5 gold pinstripes and gold serif Clarendon lettering, small PRR keystone
Most fans consider this an improvement on Loewy's conception. Why Pennsy decided to change is unclear. Most other locomotive types did wear serif lettering.
Modified Loewy Scheme in Red
1952 PRR: Tuscan Red, 5 gold pinstripes and gold serif Clarendon lettering, small PRR keystone
1953: 4876, 4856, 4857 and 4929
These few units were painted to match special red coach consists.
1955 PRR: Dark Green, thick yellow stripe and larger yellow serif Roman lettering, large PRR keystone
4885 followed by most units, including some single stripe tuscan and all single stipe silver.
This was the defacto GG1 scheme for the late 50's and early 60's.
Broadband Scheme in Red
1955 PRR: Tuscan Red, thick yellow stripe and larger yellow serif Roman lettering, large PRR keystone
1955: 4907 and 4916
As before, a few units were repainted to match special red coach consists.
Broadband Scheme - Congressional
1955 PRR: Silver, thick red stripe and larger black serif Roman lettering, large PRR keystone
1955: 4866, 4872 and 4880
A few units were repainted to match the coaches on the Congresional train. This and the green and tuscan broadband schemes used plates to cover over part of the radiatior on the side above the numbers. Three years later some units began to recieve new intakes behind the classification lights and most of those had their old intakes welded over.