Liz,
Yes, steam is a great way to refresh and enliven smashed or wilted millinery flowers. A tea kettle is best for this, as it will give you a direct stream of steam. Use as little steam as possible, holding the hat high into the jet of steam and not directly into the strong steam part (ouch!). Take care with the steam, it can be tricky to get the steam right where you want it and not burn your fingers or hands. Some folks wear gloves, but I find them too bulky for kind of work. If the flowers have been glued on (more common with the post WWII hats), it is likely a water based millinery glue and you will not want to get them too moist. It is best to work in sections, after a gentle steaming, perk up the petal with your fingers and let them cool a bit under your fingers so they will keep their new shape. I often hang a hat upside down after steaming to keep the flowers perked up while fully cooling and drying.
You might want to test an area first, as some flowers can be starched or glazed and the steam might damage them or make them sticky.
Good luck!
