I think he is asking if the frame could have been exposed to air during the dunk. The parts must remain inside the oxygen free environment until they enter the water. The same thing happened to some parts I did at school. The next run we put them deeper into the pack and they colored well. I have talked to some professionals well and if a part gets hung up in the crucible the same thing happens. The transfer from the crucible to the water has to be really fast with no chance of the parts being exposed to air. Hope that helps.