Still Air Box Basics

What is a Still Air Box?

A still air box (SAB) is a simple, enclosed workspace that allows you to work with minimal air movement. By reducing airborne contaminants, a SAB dramatically increases your success rate in mushroom cultivation.

Unlike expensive laminar flow hoods, a SAB can be built for under £20 and is perfect for beginners.

Why Use a Still Air Box?

The air in a typical room contains thousands of contaminant spores per cubic metre. When you open a sterile container, these spores settle onto your work.

A SAB works by:

Enclosing your workspace - Creating a physical barrier
Allowing air to settle - Still air means spores fall to the bottom
Limiting air exchange - Your movements don't disturb the environment

With proper technique, a SAB can achieve contamination rates below 10%.

Building Your Still Air Box

Materials Needed

Large plastic storage container (minimum 50L, ideally 70L+)
Hole saw or soldering iron (for arm holes)
Sandpaper (for smoothing edges)
Optional: Silicone sealant

Step-by-Step Build

Choose your container - Clear plastic is best for visibility. Look for one with a secure-fitting lid.
Mark hole positions - Place holes about 15cm from the bottom, spaced for comfortable arm positioning.
Cut arm holes - Use a 10-12cm hole saw or carefully melt with a soldering iron. Holes should be snug but not tight.
Smooth all edges - Sand until completely smooth to prevent glove tears.
Clean thoroughly - Wash with soap and water, then spray with alcohol.

Preparing Your SAB

Before Each Use

Wipe interior with 70% isopropyl alcohol
Spray the air inside liberally with alcohol
Place materials inside before sealing
Wait 5-10 minutes for air to settle completely
Insert arms slowly to minimise disturbance

Optimal Setup

Position your SAB on a stable surface at a comfortable working height. Good lighting is essential - consider placing a lamp behind the box to illuminate your work.

Keep your alcohol spray bottle inside the SAB, along with a flame source for sterilising tools.

Working in Your SAB

The Golden Rules

Move slowly - Fast movements create air currents
Keep arms inside - Once in, stay in until finished
Work low - Keep work near the bottom where air is cleanest
Never reach over open containers
Spray frequently - Alcohol on hands between each step

Proper Arm Insertion

Spray arms with alcohol up to elbows
Put on fresh nitrile gloves
Spray gloves thoroughly
Insert arms slowly and smoothly
Wait 30 seconds for air to settle again

Work Flow

Arrange materials from cleanest (back) to least clean (front):

Sterile cultures and agar at the back
Working containers in the middle
Tools and alcohol spray at the front
Waste/used items nearest to you

Common Mistakes

Mistake 1: Holes Too High

Arm holes placed high on the box force you to work in the upper air space where contaminants float. Keep holes low.

Mistake 2: Rushing In

Not waiting for air to settle after spraying defeats the purpose. Those 5-10 minutes are essential.

Mistake 3: Lots of Movement

Every arm movement creates air currents. Plan your work sequence and minimise repositioning.

Mistake 4: Overcrowded Box

Too many items inside creates obstacles and forces unnecessary movement. Only include what you need.

Upgrading Your Setup

Once comfortable with a SAB, consider these improvements:

Arm sleeves - Reduce contamination from arm movement
Internal lighting - LED strips provide better visibility
Larger box - More working room means less cramped movements
Laminar flow hood - The ultimate upgrade for serious cultivators

Maintenance

Regular Cleaning

Wipe down after every session
Deep clean weekly with soap and water
Inspect for cracks or damage
Replace if plastic becomes clouded or scratched

Storage

Store your SAB clean and inverted to prevent dust accumulation. Cover with a clean cloth or bag.

Next Steps

With your SAB ready, learn about pressure cooker sterilisation to prepare your substrates, or dive into our liquid culture guide to start inoculating.