Grow mushrooms the EZ way.

How to Make A Still Air Box

If I told you there was such a thing as a correct and incorrectly built Still Air Box (SAB) you might scoff at me and say “it's just a plastic box with two holes in it, how can it be built incorrectly”. Well, I’ve built a bad still air box once in the past and not only was it difficult to build and a nightmare to set up, it often resulted in just as much contamination as open-air inoculation. Eventually I came to the realization that what I created was pretty bad Still Air Box and I should probably get another box and try again, this time reading/thinking about how to setup the box correctly.

In this post, I am going to go over the correct way to make a Still Air Box (in my opinion), but first, let's cover the basics for absolute noobs who may have stumbled across this page.

What Is a Still Air Box (SAB)?

A Still Air Box is an enclosed environment which works on the principle that air inside the box is still; whereas, outside the SAB drafts and airflow from doors, windows and general movement can move air containing bacteria, spores and other small contaminate particles onto your sterile work. Normally a SAB is created from a transparent plastic tote with two holes for arms to go inside. This allows the user to view and work inside the box without breathing on their work or introducing airborne contaminants.



How to make a Still Air Box?

Things you WILL need:

  • A large tote (the larger the better as this will make organizing your workspace easier, I am pretty sure you could find one of these way cheaper in a local store. I have just linked this so you can understand the size).
  • A Tuna Tin Can. This will ensure a perfect arm hole size.
  • A Hob.
  • Oven Mitts.

Things you WONT need:

  • A drill, cutting equipment or any power tools


  • Gather your equipment.
  • Place your tote on a counter close to you.
  • Turn on the Hob and let it heat up.
  • Place the Tuna Can on the hob allowing it to heat up momentarily (about 30 seconds will do, remove the wrapper).
  • Put on your oven gloves and pick up the Tin.
  • Push the tin into the Tote (where you want your holes) and slowly rotate it whilst applying pressure.
  • Remove the tin and remove any remaining plastic.

As I said earlier it is definitely possible to screw up a Still Air Box, so here are my top tips for making sure you have a working box.

  • Choose a Box with an airtight lid (or near enough).
  • Place the box opening on the side and NOT on the bottom, this will give you easier access for sterilizing your equipment when placing things inside or taking things out of your box.
  • Ensure the holes are a few inches from the bottom of the box, this should allow your arms to rest on the table while using the box.  My first SAB had a 5-inch gap from the bottom and all it did was make me feel uncomfortable, which resulted in me rushing the process (causing contamination).
  • Do not use tape on the box at all, it will harbour contaminants.
  • Use a Large box which gives you plenty of room to move position sterilized equipment AWAY from each other. Less space makes working inside the area more stressful and creates tension which will increase the chances of an error.
  • Ensure your box is FULLY Transparent. Don't get a box you can only slightly see-through as when you spray down your box with soapy water you will barely be able to see anything.
  • Keep the Armholes small and crack-free (don't use a drill or saw). A tuna can will provide the perfect Still Air Box hole size for a forearm to fit in. The alternative is to use a power tool which even if you go slowly with light pressure can still cause cracking or misshapen holes. Alongside this purchasing power tools can be expensive and loud which is not very inconspicuous if you are trying to maintain a low profile about your new hobby. It also takes longer to build and clean up after, trust me use a 'hot can'.
  • File down the holes you’ve made to ensure there aren't any sharp edges that our gloves could catch on.

How to use a Still Air Box?

  • Place your Box on the table which you will be using with the back panel accessible.
  • Remove the back panel.
  • Place your items into the SAB (wiping each down with alcohol first).
  • Spray all the sides down with soapy water (bottom, sides, pack banel).
  • Place the back panel back onto the box.
  • Allow the Still Air Box to settle for a few minutes before beginning.

Is a Still Air Box necessary?

Depending on what strain you are trying to grow a Still Air Box may not be necessary. If you are using PK-tek, then it will be possible to inoculate your jars without a Still Air Box however the chance of contamination will likely increase without one.

If you are going to be working with grain spawn then a Still Air Box will be necessary as grain spawn tends to be more susceptible to contamination. However, there is evidence online showing it is possible to grow on grain spawn without a Still Air Box but it does require good sterile technique and experience.

For Agar work, a Still Air Box is definitely necessary.

Realistically, the cost of a Still Air Box is minimal, especially if you follow the instructions in this guide so it is probably worth while building one. If you don’t have the space for a Still Air Box you can create a small (and cheap) laminar flow hood as I have outlined in this post.

How to clean a Still Air Box?

It isn’t actually necessary to clean your Still Air Box with any sort of disinfectant before use, soapy water will do. This is because the point of the Still Air Box isn’t to be clean but to prevent air from billowing around and dropping contaminants onto your substrate. General consensus is to spray the sides of the Still Air Box with soapy water as this will causes any contaminants that move around inside the box to stick to the soapy liquid and remain there.

If you really want to clean your Still Air Box give it a wipe down with alcohol before every use but make sure the sides are not soaked and be careful with open flames inside.

What is the Perfect Still Air Box Arm Hole Size?

As small as possible, as long as the edges are smooth so your gloves won't get caught on them. 


Is it possible to use a Still Air Box without gloves?

Yes! If you wash your hands with soap thoroughly before beginning any still air box work and regularly sanitize them with alcohol during the procedures this wont be an issue.

I normally wear gloves as they are easier to sanitize and alcohol can irritate my skin.

Still Air Box Vs GloveBox

If you've ever seen what looks like a still air box but with gloves permanently built in, that is a glovebox.

Normally glove boxes are not recommended for mycology. This is because they are more difficult to make and do not seem to create better results.

Often people cite still air boxes as prefferable for the following reasons:

  • A still air box is easier to make.
  • The seal inside glove boxes cause uncontrolled increasing air move inside the box with every movement.
  • Its easier to move in, out and inside of a still air box than a glovebox (permanently attached gloves limit movement).
  • You can regularly re-santize your hands with a still air box.

So, if you are wondering whether to build a still air box or glovebox its probably best to just stick with a still air box. 

Can I Flame Inside a Still Air Box?

If you wipe you Still Air Box with soapy water (instead of alcohol) before use and have plenty of space inside the box, then it is possible to flame your needles inside a still air box. 

However it is just as easy to take your utensil out flame until red hot then return it back into the still air box to work. It really is personal preference however the safest practice is to flame outside.

If you are using a butane torch like this (amazon link) flame sterilizing is very simple and the utensil will glow red for a long a few seconds giving you time to move it back into the SAB.