If the charring of the frames has not weakened them to the point that they are at risk of breaking (in your extractor, or elsewhere), then there is no reason not to use charred frames.
They are absolutely fine and strong, just i am afraid can the black thing harm my bees ?If the charring of the frames has not weakened them to the point that they are at risk of breaking (in your extractor, or elsewhere), then there is no reason not to use charred frames.