Board Thread:Theories and Speculation/@comment-36019309-20190114073523/@comment-32685487-20190211194250

Amaterasu burns as fast or as slow as Itachi wants it to. For example, it burned instantly through the fire breathing toads stomach the moment Itachi opened his eye, showing that Itachi was able to make it INSTANTLY go at full temperature and burning speed, and against Sasuke he made it burn slower as it burned Sasuke's snake shed skin clone half to ashes before Itachi stopped it. Albeit it seems Sasuke can add shape manipulation to Amaterasu while Itachi hasn't shown that, but Itachi can control the temperature output on the tech, controlling the rate it burns which Sasuke hasn't shown.