zipost---The blue material you are thinking of is EAR C-1002 Isodamp. It is designed for constrained layer damping, which is NOT what the chassis panels of electronics benefit from. EAR also makes the stuff you want for that application: Isodamp SD125. The 125 refers to the material’s thickness: .125" (1/8"), and the SD is also available in .04" thickness. I've installed both versions on the chassis panels of my phono amp, line amp, and power amps, and heartily recommend it.
Michael Percy Audio is a great source for all the above and much more.
