When you release the liquid carbon dioxide from the tank, the expansion of the liquid and the high-speed evaporation of carbon dioxide gas cools the remainder of the liquid down to the freezing point, where it turns directly into a solid.
Quick Answer. Cigars stay fresh without a humidor for up to a month when kept in their original wrapper. Cigars kept in a humidor can last for years in a properly controlled environment. A humidor keeps cigars from drying out and the oils from evaporating. Keep Learning.
You'll want the case to be lined, so your cigars won't take on a leathery taste, and to prevent the tragedy of a fine cigar's wrapper snagging on rough, less-finished leather. The thickness of the leather is a matter of personal preference. The thicker the leather, the greater the protection.