Building a Still Air Box
Create an affordable clean workspace for mushroom culture work. Step-by-step instructions for building and using a SAB effectively.
Building a Still Air Box
A Still Air Box (SAB) is the most affordable way to create a clean workspace for mushroom culture work. With basic materials and proper technique, a SAB can achieve contamination rates comparable to expensive laminar flow hoods.
How It Works
Contamination typically rides on air currents. A SAB works by eliminating air movement—when air is still, contaminants settle rather than drift onto your work surfaces. The enclosed space creates a protected zone for transfers and inoculations.
A laminar flow hood pushes clean filtered air across your workspace. A SAB simply eliminates air movement. Different approaches, same goal: keeping contaminants away from your cultures.
Materials Needed
| Item | Purpose | Notes |
|---|---|---|
| Clear plastic tub (60-70 qt) | Main enclosure | Larger is better for workspace |
| Marker | Trace arm holes | |
| Hole saw or knife | Cut arm holes | 4-5 inch diameter |
| Sandpaper or flame | Smooth edges | Prevent cuts and glove tears |
| 70% isopropyl alcohol | Sanitization |
Building Steps
Choose Your Tub
Select a clear plastic storage tub, 60-70 quart capacity. Clear plastic lets you see your work. Larger tubs provide more working room.
Mark Arm Holes
On one long side, mark two circles 4-5 inches in diameter. Position them shoulder-width apart and about 4-5 inches from the bottom of the tub.
Cut the Holes
Use a hole saw, rotary tool, or carefully cut with a sharp knife. Go slowly to avoid cracking the plastic.
Smooth the Edges
Sand or flame-polish the cut edges. Rough edges can tear gloves and harbor contaminants.
Clean and Test
Wipe the entire interior with 70% isopropyl alcohol. Let dry completely before use.
Setting Up Your Workspace
Clean the Area
Work in a clean room with minimal air movement. Turn off HVAC, fans, and close windows.
Prep Everything First
Gather all materials before starting: agar plates, tools, cultures, alcohol, lighter, labels.
Sanitize the SAB
Wipe all interior surfaces with 70% isopropyl. Let evaporate completely—alcohol vapor is flammable.
Arrange Materials
Place all items inside the SAB before inserting your arms. Minimize movement once work begins.
Wait for Settling
After placing your arms through the holes, wait 30-60 seconds for air to become still.
Let all alcohol evaporate before using a flame. Alcohol vapor inside an enclosed space is a fire hazard.
Best Practices
Minimize Movement
Every movement creates air currents. Work slowly and deliberately. Keep your movements small and controlled.
Position Open Containers
Point open plates and jars away from you. Your breath, skin, and clothing are significant contamination sources.
Work from Cleanest to Least Clean
Start with your clean cultures, then move to more questionable material. Don't go back to clean plates after handling unknown cultures.
Keep Sessions Short
Air quality degrades over time as you work. Complete 5-10 transfers, then close up and take a break.
Common Mistakes
| Mistake | Problem | Solution |
|---|---|---|
| Rushing into work | Air currents haven't settled | Wait 30-60 seconds after inserting arms |
| Talking while working | Breath carries contaminants | Work in silence or wear a mask |
| Working too long | Air quality degrades | Keep sessions under 30 minutes |
| Ignoring drafts | Air currents enter through holes | Ensure room air is still |
| Wet alcohol inside | Fire hazard | Wait for complete evaporation |
Upgrades and Modifications
Arm Sleeves
Attach long rubber gloves or fabric sleeves to the holes. This reduces the size of the opening and limits air exchange.
Glove Ports
Install actual glove ports from laboratory suppliers for a more sealed system. More expensive but reduces contamination.
Alcohol Wipe Station
Keep a small tray with alcohol-soaked paper towels inside for wiping down items during transfers.
Expected Results
With proper technique, a SAB can achieve:
- Agar work: 90-95% success rate
- Grain inoculation: 90-95% success rate
- LC work: 85-90% success rate
Results depend heavily on technique. Practice improves outcomes significantly.
For sterile technique details, see Mycology 102. Ready to upgrade? Consider a Laminar Flow Hood.
Quick Reference
Cost: Under $30 Build time: 30 minutes Skill level: Beginner Best for: Hobby-scale culture work Limitations: Short working sessions, technique-dependent