Preserving flowers

Every time I dry my roses out, they turn a really dark colour and it isn’t the nice red it was or even a nice dark red.

I’ve heard of using hairspray to help preserve them but I’m not sure if you are supposed to spray before or after you hang them?

Usually once my roses have bloomed I’ll take them out and hang them upside down on a hanger :)

Any tips would be appreciated ☺️☺️☺️