Again, choose heavy books to provide the most weight. Stack them somewhere they won’t get knocked into easily. You could also use bricks instead of books for the same effect. Set a reminder on your calendar to check the flowers after a few weeks have passed to see if they’re done. They should feel like fine tissue paper. If they aren’t done yet, carefully shut them back into the book for another week to continue pressing them. It takes less time to press flowers with heavy books than if you were to use a wooden flower press because there is considerably more weight being applied from the books.

Summary:
Stack on 2 to 3 more books to provide extra weight. Leave the flowers alone for 1 to 2 weeks to allow them to dry out fully.