The Illinois Institute of Technology was formed from a 1940 merger of the Armour Institute of Technology and Lewis Institute. New colors were needed for the Illinois Institute of Technology, and since scarlet and gray were not being used by other colleges or universities in the region, those colors were officially approved in 1940. There was probably another reason these colors were chosen: Massachusetts Institute of Technology, Stevens Institute of Technology, and Worcester Polytechnic Institute all use combinations of red and gray school colors.
Vintage collegiate memorabilia from Illinois Tech exhibits a wide range of light to medium grays, but the official tone is a medium shade of gray.
According to a 1927 list, the Intercollegiate Bureau of Academic Costume (IBAC) had assigned a hood lined canary yellow with a wide black chevron to Armour Institute and a hood lined white with a Yale blue chevron to Lewis Institute. When these two schools merged to create the Illinois Institute of Technology, the Bureau assigned the new school a hood lined scarlet with a gray chevron in the late 1940s or 1950s. This description first appeared in a 1969 IBAC list and then without change in a 1972 IBAC list.