How to Build a Still-Air-Box (SAB)

How to Build a Still-Air-Box (SAB)

What is a Still-Air-Box?

A Still-Air-Box or SAB is a clear container with restricted airflow that reduces airborne contaminants such as bacteria and spores. Agar cultures, grain spawn, and other mycology projects are placed within the SAB and accessed by armholes. While not perfect, a sterilized Still-Air-Box will significantly improve the success rate of mycology projects.

What does a Still-Air-Box Do?

The SAB acts as a protective bubble from airborne contaminants. The air around us is full of bacteria, spores, and other contaminants that will outcompete young mycelium. They move around on air currents and are slowly falling to the ground. Creating still air and sterilizing surfaces will create a safe working environment.

The armholes are the SAB's Achilles heel. Contamination could creep in from mini air currents created from entering and exiting the SAB. Try to reduce the number of times you go in and out of the SAB and sterilize frequently.

When is a Still-Air-Box Needed?

During the early stages of development, spores and mycelium are highly susceptible to contamination. Using a still-air-box or flow-hood is vital whenever working with agar, liquid cultures, spore syringes, grain spawn, and other projects where the mycelium is young and uncolonized. In most cases, the mycelium is usually strong enough to fight off infection once you are ready to introduce colonized grain spawn to a bulk substrate. As a personal rule, if a project can fit inside the SAB, then work there.

Examples of Contamination
Examples of Contamination.
  • Fingerprint (red)
  • Rain-Puddle (blue)
  • Open-air near a window (top-yellow)
  • Open-air of lab-area (bottom-yellow)

Instructions to Build a Still-Air-Box

Duration: 10 minutes

Creating a Still-Air-Box is a cheap and easy DIY project that should only take around 10 minutes. You may even have the needed tools and supplies at home. In the walk-through below, we are simply cutting two 4-inch holes into the side of a clear plastic tote. Plastic totes crack easily, and some finesse is needed when cutting the holes. Slow and steady is the key here. You'll also need to keep the tote as stable as possible. I found success by securing the tote against a wall to drill the holes. There are many other ways to create a still-air-box; I found using the hole saw kit to be a very efficient method, and the kit comes in handy for other mycology projects like modified mono-tubs.

Tools & Supplies

  • Drill
  • Sharp Knife/Razor Blade
  • Hole Saw Kit: The round saw blades connect to a drill bit for cutting holes. The hole saw bits are easy to assemble. Ensure all aspects of the bit are fastened tightly, and be careful not a activate the drill while your hands are near the blades.
  • Large Clear Tote:: You'll need a large clear tote. Larger the better, 70+ quarts. Most big box stores sell them for $15-25.

Safety Tips

Fire Marshall Bill from In Living Color (early 90s)
  • Use eye protection. Glasses or sunglasses will suffice to protect your eyes from bits of plastic.
  • The tote will bend as you drill into it, making it easy to slip. Ensure your hands are at a safe distance from the drill bit. Be aware of where both hands are at all times. NEVER remove debris from the hole saw bit with your fingers
  • Toxic fumes. Avoid melting the plastic as the fumes are very toxic.
  1. Still-Air-Box Determine Armholes
    Plan Armholes

    To work comfortably, you'll want to make the armholes shoulder-width apart. Mark the center of each armhole and ensure they are correctly aligned.

    You'll want to drill the armholes at shoulder width apart. Mark the center of each hole and ensure they are correctly aligned.

  2. Attach Hole Saw Bite to Drill
    Attach Hole Saw Drill Bit

    Assemble the 4 inch hole saw:

    1. Attach the metal plate with the prongs facing away from the blades.
    2. Slide the drill bite through the metal plate.
    3. Tightly fasten the bolt to secure the hole saw to the drill bit.
    4. Attach the hole saw bit to your drill.
    5. Ensure everything is fasten securely.
  3. Still-Air-Box Drilling Armhole
    Drilling Armholes

    Align the drill bit with the first marked hole created in step 1.

    Using your free-hand, stabilize the tote but keep it away from the drill bit. Plastic totes bend easily, so the bit could slip.

    Begin drilling the hole slowly until the drill bit punches through the center mark and the teeth of the saw touch the plastic.

  4. Still-Air-Box drilling through
    Using the Hole Saw

    Ensure the hole saw it touching the plastic and begin drilling very slowly. Don't rush this part, drilling too fast can cause the plastic to crack.

    Continue drilling while apply slight pressure in a clockwise manner until the hole saw punches through the plastic.

  5. Remove Hole Saw Debris
    Removing Plastic Debris

    Safely remove the plastic ring from the drill bit. Never remove the plastic from the hole saw with your fingers while it's attached to the drill. Either remove the entire hole saw bit or grip the plastic with needlenose plyers and slowy run the drill in reverse.

  6. Still-Air-Box drill second armhole
    Second Armhole

    Repeat the steps for the second arm hole. Heads-up the tote will become more flexible with the first hole drilled out.

  7. Still-Air-Box Trim Edges
    Trim Edges

    Cut away any jagged edges around the holes. A razor blade or scalple works well.

  8. Completed Still-Air-Box

    Thoroughly clean and disinfect the SAB before using.

How to Use a Still-Air-Box

  1. Turn off ventilation Around 1-2 hours before working to allow the air to settle.
  2. Shower and wear clean clothes to reduce any contamination on your person. You may want to wear a facemask as yoru breath will create air currents.
  3. Sterilize the SAB by wiping it down with disinfectants.
  4. Setup the SAB on a clean and non-porus surface.
  5. Spray the Air inside and out of the SAB with. The droplets will cling to any contamination and pull it to the ground. Clean surface shortly after spraying.
  6. Use a raised wire rack to increases success rates as any contamination can fall from the air and amass on the surface.
  7. Place your mycology project within the SAB methodically disinfecting every item before and after it enters the SAB.
  8. Get to work. To be safe, I typically spray the air within the SAB again just before starting.


Hole Saw Kit

As you can see from above, a hole saw kit allows you to breeze through making a SAB in no time. Most kits come with a wide-array of drill sizes that come in handy when building fruiting chambers or other DIY projects. Check your local hardware store to purchase a kit. The hole saw kit I purchased online is below:

Desk Lamp

The clear plastic of a still-air-box distorts your vision slightly, so a good adjustible light source is recommened. Clip-on desk lamps are a great addition to your work area.

Dissection Kit

If starting out, I suggest buying a dissection kit. They typically contain stainless tools such as scalpels, tweezers, scissors and many more to aid you in mycology work.

Stainless Steel Wire Rack

A raised wire rack will help increase your success rate. Contaminates that are lingering in the air fall to the surface and amass. Working on a raised surface adds distance between the contamination risk and your project.

Portable UV Sanitizer Lamp

UVC light can help disinfectant your projects to further increase successful results. UVC light in the 200-280NM wavelength kills off bacteria and viruses.

Take great caution when using UVC light, and never expose your eyes or skin to the light; UVC light is a known carcinogen. The one I use is on a timer, giving me ample time to leave the room before it activates.

To be perfectly honest, I'm not sure if the portable UVC lamp I purchased does anything, but I like to take extra precautions when it comes to mycology. Here is an excellent video explaining "How to know if a UVC device will be safe and effective."

How to know if a UVC device will be safe and effective