Here's a cool point:
1. Urahara is a great scientist (the best) and created the hogyoku.
2. Urahara most likely knows how to use it fully and understands it completely since he's the CREATOR.
3. Urahara used it on himself, if not...why the HELL did he make it...
4. Urahara didn't show Ichigo cuz its just plain retarded to do so at those early stages and probably even now. Also, if he showed it, readers would be like WTF before we even knew what the hell ban-kai was...
5. Urahara is never "on time/late". He always comes at the best time to serve his purpose of protecting the masses. (ie destroy Rukia's powers, hide hogyuku forever, masses thus protected)
Here is the point:
the only reason Ichigo was able to become a vaizard was because Urahara did it. Doing research on hollow/shinigami boundaries and creating the hogyuku thereafter...I'm SURE he knew of natural ways to break the barrier.
Thus, he shows up after Ichigo gets owned...rather than before. Then begins a method of returning Ichigo's natural shinigami powers (which im sure he knows of) as well as creating a hollow within him as well. Of course he wouldn't tell Ichigo...because that would be the same as just showing off his own mask...STUPID and POINTLESS...and we'd still be like WTF IS A BAN KAI. lmao
TADA...MAKES SENSE TO ME!
Aizen is gangsta for making everyone wear white.
Tousen: "So what are we going to wear anyway? how do we tell each other apart from the shinigami?"
Aizen: "I GOT IT....lets wear exactly what they wear...but make it WHITE!"
Ichimaru: "OH SH*T, now THATS gangsta!"
Tousen: "....even I wouldn't say that..."
Aizen: "Loosen up Tousen...check this out...lets show him Gin!"
Tousen: "... 0_0 ..."