has to be completely sterile air. if you do it in open air, you'll just get a batch of mold. all it takes is one tiny spore to get in the flask and the cultures done for[b said:Quote[/b] (jon @ April 10 2004,11:11)]How starile do the conditions have to be when doing TC? Will I have to make a hood or will I be able to do it in the open air with out contamination?