Jim Darley at ProSciTech in Australia notes:

>>Kern-echt-rot. Its spelling is obvious if you know some German and its 
seems 
very unlikely that somebody had the name "Kernechtrot"
Kern=Nucleus or center; Echt=genuine, true or real; Rot=red.
Rot is never spelled Rott, not in German.
Richard is right, computer searches are unforgiving even with a word's 
ending.<<

"Echt" in ordinary German certainly means genuine, true, or real. In the dye 
world it translates as "fast" - in the sense of resistance to washing out, 
bleaching, or other forms of degradation - hence "nuclear fast red".

Bob Richmond
Samurai Pathologist
Knoxville TN