I honestly have never seen a purse that large for a switchblade or any other knife for that matter. That is way cool. As well it's really hard to find any of these fishtails with the black handles that haven't shrunk or cracked. The blade looks to be in primo condition too. Let me know should you ever decide to sell this beauty. Thanks for posting Dale.
Buy them with no shrinkage! :O) I would think keeping them at a reasonable temperature. I would think too much heat might cause them to dry out. I don't know about celluloid, but I have heard if they start gassing to keep them away from your other knives or they could be ruined too.
Probably nothing. The general consensus is that the celluloid may have not been cured properly as some celluloids seem to have no ill effects. Best to keep them out of extremes of temperature as well lengthy exposure to light and yes when they start to offgas they will corrode any knives in proximity.