Board Thread:General Discussion/@comment-31283382-20140611172614/@comment-11051098-20140729121544

Hollow Ichigo has always been a part of him, and still is. He should be able to do it, but Hollow Ichigo, or Zangetsu as he is, always burst out in full Hollow mode when Ichigo was in trouble and "Old Man" Zangetsu decreased his suppressing of him and let him out.

Now that Ichigo has come to "peace" with both of them, who knows. I would believe he can still go into a full Hollow mode, though.