Chapter 03
Storage foundations
Heat, light, and humidity. Get those three wrong in Arizona and the chemistry does the rest.
The three thieves
Temperature. Hold a steady indoor range — roughly 50–70°F is the textbook; a climate-controlled interior closet is the realistic den. Heat does not just ‘age’ bleach. It can make oxidizers unhappy. Swings crack seals as containers breathe.
Light. Ultraviolet spends iodine, peroxide, and many organics. Opaque bins, amber glass, mylar, a closed cabinet. A pretty jar on a sunny sill is a display, not a store.
Humidity. Under 50% is the aim; drier is better for powders. The Valley is dry until monsoon, and then every bag of salt, lye, and calcium chloride will drink the air. Desiccant packets are not decoration.
Three workhorse containers
| Container | Use it for | Skip it for |
|---|---|---|
| Glass (amber when the chemical hates light) | Acids, iodine, oxidizers you trust not to pressure-build, tinctures | Kids’ reach, bounce-around truck kits, anything that freezes and can burst |
| HDPE (recycle 2) | Dry powders, dilute solutions, lye (with a good cap) | Strong solvents; do not assume every plastic is HDPE |
| Mylar + desiccant | Dry food-adjacent powders: salt, citric acid, baking soda, DE | Liquids, oxidizers that off-gas, anything sharp that will puncture |
Default to glass when you are unsure. Metal lids corrode over acids and iodine — use a poly liner. Never store lye in aluminum. Never store iodine in cheap thin plastic and then act surprised at the brown stain in the cupboard.
Desiccants are not oxygen absorbers
Silica gel fights water. Oxygen absorbers fight oxygen, and they are for dried food with a little residual moisture — not for a jar of baking soda, salt, or pool shock. Do not throw both into a chemical jar ‘to be safe.’ You will cake the powder or waste the packet.
Indicating silica gel that has changed color can be dried in a low oven on a tray until the color returns, cooled in a sealed jar, and reused. That loop is years long if you do not scorch it.