2010-10-30, 10:05 PM
The portal frame is just ordinary Obsidian. If any of it is damaged then the portal poofs and has to be relit. The swirly blocks that warp you are about a third of the depth of an ordinary block. Just like Half blocks, if you place a block over it there will be empty space.
I do not think liquids affect portals at all, but the game will not spawn your portal in lava or something.
I do not think liquids affect portals at all, but the game will not spawn your portal in lava or something.