As an oldie (33) I can remember back to the interim period between 77 and 80. The volcano thing was certainly about before ESB was released, but it was closer to the release of ESB than to the release of ANH I think.
I think that the old Star Wars comics between ANH and ESB had mention of it. Of course it isn't canon.
Here is the closest I could get from SW.C
Vader & Lava
I dont remember hearing anything about his Lava accident till near ROTJ. I also remember David Prowse and Mark Hamil saying that they didnt even know that Vader was Lukes father till the premier of ESB.
Do you mean how they didnt know about Vader/Father?
They shot the scene with different dialouge, then later in editing, they called them in for looping. There they recorded the 'real' lines that would be used but they had been throwen around so that unless you were the editor or GL you wouldnt know what scene you were recording for.
If you look close you can see Luke isn't quite sync'd up. He sometimes adds a word or two when his lips arent moving. ANd some words where his lips are moving but not to the right words.
I found another mention of a lava cave in SW.C. It says that early set designs of the Emperors chamber were to be under Corusant in a lava filled throne room. It must be something GL likes, but has never got to include in any film he's made.
Do you mean how they didnt know about Vader/Father?
They shot the scene with different dialouge, then later in editing, they called them in for looping. There they recorded the 'real' lines that would be used but they had been throwen around so that unless you were the editor or GL you wouldnt know what scene you were recording for.
If you look close you can see Luke isn't quite sync'd up. He sometimes adds a word or two when his lips arent moving. ANd some words where his lips are moving but not to the right words.
I found another mention of a lava cave in SW.C. It says that early set designs of the Emperors chamber were to be under Corusant in a lava filled throne room. It must be something GL likes, but has never got to include in any film he's made.
I heard in the Star Wars site that one of the artists were asked to do a picture of Vader's home, in it he had a sea of Lava. Also I just have to say that GL knew in A New Hope that Vader was Lukes Father. it was planned from Day one. I think this is said on the tape "From StarWars to Jedi" Oh if you look around in the StarWars.com page you can probably still find the Lava pic.
Ok, even if GL DID know that Vader was Luke's father- and that really is a VERY contentious point because there is a lot of stuff that suggests it is not so- Mark Hamil CERTAINLY didn't, so he would not have been asking about his father/Vader as one person.
BTW, KJ, more than just the first script of ANH had Vader dying at the end, so if GL DID have that in mind he put it in way after the first script.