I haven't been on that much,but you all pretty much posted for me what James was looking for.Thanks to all those for posting the links and etc.
Most of the time,like Scott said, it's just sheer luck.I don't really know why or how it happens,just I believe having pockets of air bubbles trapped in the rim sometimes has something to do with it.Then again,I have had bubbles that were hollow as well.A wetter dough seems to help too.
I had some more photos on my other PC I wanted to post,they are not in my photobucket account,and the hard drive crashed.So I have not been able to retrieve them yet.I had planned to transfer all my pics to a Disc,but kept putting it off.So if you got pics in your HD,do back them up or copy them!!
James,I look forward to any experiments you turn up.Even if the rim doesn't look or blow up as much,put a camera close enough inside,it will enhance the image and look larger than it is,hence more detail.
Hope you all are enjoying the weather these days.Perfect for Pizza making!