Riso RP Color Codes
Here's a list of color codes for the RP series (should work on all models, have been tested on a RP3100UI and RP3700).
Unlike with newer machines which use chips to show the appropriate color on the Riso, the ink must be manually dialed in on the RPs through a Test Mode setting. It is however not necessary to change the color code on the drum after swapping ink colors but if you want the Riso to show the corresponding drum color on the display, you can use the codes to update the drum settings after changing inks.
See below for steps & codes.
Steps
Start up in Test Mode: Press and hold the "Left" & "Right" registration buttons while turning on the printer until Test Mode shows. Make sure the drum you want to change the color code of is inside the Riso.
Enter 587 (this will take you directly to the setting "Ink color code")
Press the green Start button.
Now enter the test codes according to the ink inside your drum (either enter the number or use the "Up" and "Down" buttons on the touch screen.
33: Black
34: Blue
35: Blue 2
36: Blue 3
37: Blue 4
38: Red
39: Red 2
40: Red 3
41: Red 4
42: Green
43: Green 2
44: Green 3
45: Yellow
46: Yellow 2
47: Brown
48: Brown 2
49: Purple
50: Purple 2
51: Gray
52: Gray 2
53: Lightgray
54: Lightgray 2
55: Orange
56: Orange 2
60: Silver 2
61: Pink
62: Pink 2
63: Custom