scissors Posted June 26, 2015 Report Share Posted June 26, 2015 So, the envirovent was accidentally left off during a slow bisque fire. Obviously, the kiln atmosphere was not oxygen rich. Can the work be re-bisque fired to correct some of the potential problems? Link to comment Share on other sites More sharing options...
bciskepottery Posted June 26, 2015 Report Share Posted June 26, 2015 Unless you are using a clay body that has a tendency to bloat, pinhole, etc., there is no need to rebisque. Some of the "black" firing clay bodies that are really iron-rich like an oxygen rich bisque; but if you are not using a clay like that, you should be okay. Link to comment Share on other sites More sharing options...
TJR Posted June 26, 2015 Report Share Posted June 26, 2015 The purpose of the vent is for the potter, not the clay. As pots are bisqued, they give off sulfur dioxide which is nasty to breathe. If your bisqueware made it, no need to re-do it. TJR. Link to comment Share on other sites More sharing options...
Mark C. Posted June 26, 2015 Report Share Posted June 26, 2015 I just finised a bisque last night in an electric with no vent. I never have had a vent in any electric as kilns are outside. I only bisque in them.My clay is porcelain. Mark Link to comment Share on other sites More sharing options...
timbo_heff Posted June 26, 2015 Report Share Posted June 26, 2015 The vent is for the wares and the potter but since the clay is now sintered, rebisque fire will not get any more of the potential problems out; once sintered, the clay cannot release those gasses until near top temp when the clay is as close to molten as it gets. Link to comment Share on other sites More sharing options...
Marcia Selsor Posted June 27, 2015 Report Share Posted June 27, 2015 I don't use a vent since my kilns are in an outside shed. It is ok. You don't need to re fire. Link to comment Share on other sites More sharing options...
curt Posted July 6, 2015 Report Share Posted July 6, 2015 The vent is for the wares and the potter but since the clay is now sintered, rebisque fire will not get any more of the potential problems out; once sintered, the clay cannot release those gasses until near top temp when the clay is as close to molten as it gets. No doubt one would rather have off-gassing completed at a lower temperature, but I just wonder if there might not be some positive effect even after the clay has already been to bisque temps. My impression of sintering was always that it was just the welding/joining of the tips of the clay particles. A bisqued clay body is still very porous so I would have thought that (in principle) gases could still escape. Not advocating going to all the trouble and expense of re-firing unless you know for certain you are going to have some bloating issues. but just a thought. Maybe I am missing something? Link to comment Share on other sites More sharing options...
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