Here's a longer article in the Germany newspaper Süddeutsche Zeitung that has details: http://www.sueddeutsche.de/panorama/aktion-auf-rechtsrockfestival-trojan

Here's a longer article in the Germany newspaper Süddeutsche Zeitung that has details: http://www.sueddeutsche.de/panorama/aktion-auf-rechtsrockfestival-trojaner-t-hemd-legt-neonazis-rein-1.1129735 http://www.sueddeutsche.de/panorama/aktion-auf-rechtsrockfes... Apparently, they printed about 50 shirts using different mixes until they got the desired result. It sounds like it's simply two layers of printing, the lower one using regular washing-resitant ink, and the on top using an ink that comes off in the washing machine - but not from simply getting wet (since that would have risked early discovery). It may be temperature-dependant.