I have been contacted by 3 sisters. They would each like to bring me fabric in various forms and have me create headwear for them. There will be a prom gown, a christening gown, and yardage of fabric bought many years ago. 

How can I be sure the gowns can stiffened, molded, and tooled? They have no idea the fabric content, there are no labels, and I have not yet seen the items. I am thinking that I could cut a tiny fraction of the yardage for a burn test and stiffening test but how can I ensure the gowns are usable? Each wants several large flowers as well.