Working With Pressed Flowers

Hi, All!

I know pressing flowers has been addressed already here, so bear with me, please.

I would like to know HOW they make all the pressed flowers adhere totally flat to the paper as in greeting cards from oversees, where every tiny little sliver is perfectly flat and adhered. Do they iron them on with wax paper? Is there some kind of spray material to accomplish this?
I hope some of you have seen these cards. They look like they are made on home-made paper and are quite beautiful. Many of them come from Northern Europe--maybe Poland or Lithuania.

Please help! Any ideas are welcome.

Thanks, Gita