Display Cases - Question

[Calaski8123]

My Captain at work has a display case in his office that he got from this website:

http://www.customdisplays.com/index.html

It is very nice and the price is great. I have heard though certain woods are bad for the medals and other items (dagger, armband, photos) because of gases they give off can cause tarnishing or deterioration. This site offers Oak, Cherry and Walnut. I heard walnut was a good wood to use, but I really don't like the color. The oak I have been told to stay away from. I do like the cherry cases, but I haven't heard anything good or bad about them.

Can someone please fill me in on what is good or bad about the woods and if these cases seem OK? Also, would the fact that they have finish and a gloss lacquer finish help control the harmful gases the wood gives off?

Thanks!

Jim