User blog comment:Jaadowgg/Nen Category/@comment-5780397-20180221185710/@comment-25814498-20180221222943

It seems to me that it would only be the case if the contents began spilling over the glass, since conjuration simply involved creating new matter out of Nen, not changing pre-existing matter. Transmutation doesn't suit either, since it purely involves changing the properties of Aura instead of matter, so I can only envision it being specialisation as a result.