http://wiki.answers.com/Q/How_do_you...to_preserve_it
How do you harden a beehive to preserve it?
Answer
I've been trying to answer this question for myself, and have found several answers, depending upon which type of beehive you want to preserve.
My husband found a hornet's nest fallen on a trail in the woods, so he brought it home for me. Since then, I have been trying to figure out how to preserve it. So far I have read that for a hornet's nest:
you can spray it occasionally (and very lightly) with an aerosol hairspray,
just hang it up in a place in the house where it will least likely be touched and be subject to vibrations, and
I found more information on the following link:
http://www.ipm.iastate.edu/ipm/iiin/bhornets.html
I hope this helps, although your question was specific to hardening it. I also read that you can put a light coat of acrylic finish on it (like what you would use for wooden furniture), however when I read this there was information to the contrary regarding the fact that this is unnecessary, but that would again depend on whether the objective of hardening the hive was to preserve it.
My next step is that I am going to stop by my local taxidermist and confirm whether there are other options that I have been unable to find on the internet.
Good Luck!