In a sealed freezer bag, preferably somewhere that is dark, dry, and not subjected to excessive temperature swings. Particularly exposure to UV radiation (sunlight) and excessive heat (summer days) will have adverse effects on slingshot rubber.
A well placed cupboard inside the house is doubtlessly the best option: slingshot rubber and ready-made bands should last for years without problems.
Ordo thanks for the link.
Port Boy and Pebble Shooter I appreciate your input, I live in a year round hot climate and the house can get really hot when I'm at work I have multiple types of bulk bands on their way via post, seems like the fridge might be the best option. Legends, thanks.
This afternoon I pulled some old .030" amber latex from the fridge and cut a set of 18mm x 12mm bands. This latex was purchased in July 2014 from Tex Shooter. I still have the electronic receipt for two 10.5" x 16" sheets. The amber latex has no UV protection so it would be more sensitive to light and heat than the current colored latex offerings that are now popular.
From the same latex batch I once cut a set of bands for a local fellow who left his slingshot on his truck dashboard all summer. Before fall hunting season he asked for a new set of bands and showed me the brown and brittle set that was still on the frame. A light tug on these bands would easily snap off a section of the wavy rubber. The heat and UV rays destroyed the bands.
From this same latex batch I had cut several sets of bands and used them until breakage. I have a used set that has been sitting on a shelf in my basement for years. They still shoot but with much less power. The color changed a bit but they are not brittle.
The rest of the latex sheet was stored in a Ziploc in the fridge crisper since July 2014. The color still looks good. The set that I cut today feels good and tosses a ball with reasonable speed. Band length was adjusted for my draw so the measurement at the pouch decreased to 17mm.
Hygenic .030" Latex (purchased July 2014)
17mm x 12mm x 190mm
.028" measured thickness
32" draw length
Draw weight 8lb 11oz
5/16" steel = 215 fps
3/8" steel = 189 fps
The old .030" Hygenic latex still seems to shoot with acceptable speed. Back when this batch was new I was using 3/4" straight cuts and getting around 190-195fps with the 3/8" steel using fresh bands. The bands that I was shooting today would draw a bit lighter than the 3/4" straights.