I was watching the SG-1 earlier and realized something. When a Stargate is locked there is a surge (for lack of a better word) in front of the gate. Carter says it is unstable wormhole etc. Also says that whatever stands in front of it at that moment is gone.
However several times I noticed that they establish the wormhole while the Iris is closed. It seems to me that the Iris should be vaporized. Is there any explanation why it doesn't?