Still Air Box (SAB)build

Still Air Box (SAB) Construction and Protocol

A Still Air Box operates on the principle of particulate settling rather than filtration. It provides an immediate, low-cost vector mitigation zone for agar work and inoculations prior to scaling up to a positive-pressure laminar flow hood.

Core Component Procurement

Material	Specification	Commercial Sourcing	Purpose
Storage Tote	56 to 106 Quart, highly transparent, gasket-sealed lid preferred.	Local hardware or big-box store.	Primary isolation chamber.
Cutting Implement	4-inch to 5-inch diameter metal cylinder (e.g., empty coffee can) or hole saw.	Grocery store / hardware store.	Creating ergonomic arm ports.
Heat Source	Butane torch or kitchen stove.	Hardware / kitchen supply.	Thermal cutting to prevent acrylic/plastic micro-fractures.
Elevated Deck	Stainless steel wire cooling rack.	Kitchen supply.	Keeps cultures out of the heavy particulate sink at the bottom.
Particulate Trap	Spray bottle with a 10% dish soap to water solution.	Grocery store.	Traps airborne spores against the SAB walls.

Assembly Architecture

Port Alignment: Place the tote upside down on your work surface. Sit in your standard lab chair. Mark two circles on the wide side of the tote, shoulder-width apart, at a height that allows your forearms to rest comfortably inside without straining.
Thermal Penetration: Using a drill with a hole saw often shatters brittle polypropylene totes. Instead, grip your metal cylinder with heavy-duty pliers, heat the rim with a torch or stove until extremely hot, and press it directly through the marked circles. This melts a clean, structurally sound 4-inch to 5-inch port.
Edge Remediation: Once the plastic cools, use medium-grit sandpaper or a utility knife to deburr the melted edges of the arm ports so they do not catch on your gloves or skin.

Operational Protocols and Sterile Technique

The Soapy Water Trap: A SAB is not sterile; it is still. Spray the interior walls and ceiling with the soapy water solution before working. The soap acts as a surfactant, causing microscopic dust, bacteria, and mold spores to stick to the walls rather than floating into your agar plates.
The Elevation Strategy: Heavy contaminants settle to the bottom of the tote. Place your wire rack inside and conduct all inoculation work on top of it, creating a buffer zone between your sterile media and the contaminant sink below.
Fluid Dynamics: Move slowly. The primary failure point of a SAB is the operator pumping contaminated room air into the chamber through rapid arm movements. Enter the ports slowly, execute your transfers, and exit slowly.
Combustion Hazard: If using 70% Isopropyl Alcohol (IPA) to sanitize the interior, do not use a flame inside the box to sterilize your scalpel or syringe needle. The fumes will pool and ignite. Flame sterilize outside the box, cool the tool inside the box on blank agar, and execute the transfer.