What is a still air box (SAB)?

A still air box matters because air carries the spores that ruin cultures. The Cornell Small Farms and Fungi Ally farm guide lists air first among the seven vectors of contamination: "In every breath we take we inhale fungal spores" (Cornell Small Farms and Fungi Ally). Cornell adds that "sterility becomes much more critical when using high nitrogen materials like agar, grain, and supplemented sawdust" (Cornell).

UF/IFAS Extension's oyster guide says tissue cloning is ideally done "inside a still-air transfer chamber or a laminar flow hood to avoid airborne contamination" (UF/IFAS).

Use a still air box by cleaning it, loading everything first, and working slowly with containers open as briefly as possible. Use it to pour agar, inoculate grain spawn and make transfers.

1. Set it up. Stand the tote upside down on a clean table, arm holes toward you.
2. Clean it. Spray the inside, the table and everything going in with 70% isopropyl alcohol, and let it evaporate rather than wiping it off. The farm guide says "it is during the evaporation process that the alcohol kills microorganisms" (Cornell Small Farms and Fungi Ally). UF/IFAS cleans its work table with 70% ethanol (UF/IFAS).
3. Flame tools outside the box. Heat a needle or scalpel tip red-hot, then let it cool before use (UF/IFAS). Do it away from the box and the alcohol: North Spore's instructions warn, "Do not use an open flame inside a still-air box" (North Spore). Alcohol vapor catches fire: in one Stanford lab, a Bunsen burner "ignited the ethanol vapors" (Stanford EHS).
4. Work slowly. "Move slowly and with intention," the farm guide says (Cornell Small Farms and Fungi Ally), and keep each plate or jar open for as little time as possible (SARE).

A still air box is the low-cost choice for small batches, and a laminar flow hood is the better tool if you can get one. A flow hood blows filtered air across the work; the farm guide wants a filter rated 99.99% at 0.3 micron (Cornell Small Farms and Fungi Ally). A SARE-published lab guide turns the hood on at least 10 minutes before use (SARE).

For pouring agar, GroCycle prefers a flow hood but says a still air box "will also help reduce contamination" (GroCycle). For injecting liquid culture through a self-healing port, GroCycle says sterile conditions are much easier to keep, and a clean room away from drafts can do without either (GroCycle). Our syringes guide walks through that inoculation.

• Fast arm movements, which stir up the air the box is meant to keep still.
• Wiping alcohol off before it has had time to work.
• Flaming inside the box, next to the alcohol you just sprayed.
• Not measuring the result. Hypha compares each strain's success and contamination rates, so you can see whether a change in technique paid off.

If a batch still contaminates, the contamination ID guide helps narrow down the cause.