Updated: Mar 23
A Still Air Box, often referred to as a “SAB” for short, is an easy and relatively inexpensive way to drastically lower contamination rates when trying to grow mushrooms. Essentially, a SAB is a piece of equipment which serves to create an area with no air movement that can be easily disinfected. This is important in regard to Mycology because every cubic meter of (unfiltered) air contains MILLIONS of Fungal and Bacterial spores, along with other potential contaminants that can harm or compete with the mushroom culture you are trying to grow.
A Still Air Box is typically built using a large plastic container which has been modified so that a user may conduct sensitive mycological tasks (like inoculation or agar propagation) inside the container without opening the container’s lid. This is accomplished by drilling two large holes in the plastic container, and securing rubber gloves to these holes. You can then place your hands inside the gloves, disinfect the interior of the box, and work freely inside the box without worrying about contaminants getting into your mushroom culture.
Professionally built SAB’s are also available, however are notably more expensive than it will cost to build your own. Another alternative to building a SAB is purchasing or building a “Laminar Flow Hood” however this piece of equipment is also quite expensive, so most beginners end up starting with a home-made SAB.
Building your own Still Air Box is well within the grasp of most individuals, requires only basic tools, and will cost about $50 plus a few hours of your time to complete - a good trade off for lowering contamination rates by as much as 50%.
To make your own SAB, you will need the following materials;
A large plastic container (the bigger the better)(we recommend a container around 80L in size)
2x 6” Toilet Flanges
Large "Heavy Duty" Rubber Gloves
8x 1.5” bolts
8x compatible nuts
A ½” Drill Bit
A ¼” Drill Bit
You will also need the following tools;
A Caulking Gun
An adjustable wrench OR ratchet and appropriate bits.
STEP 1 - Use the sharpie to mark where you want the glove-holes to go. Be cognisant when deciding where the holes will go, and make sure that the placement allows you the ability to reach anywhere inside the box. We recommend placing the holes about 4” from the bottom of the container.
Now place the THINNER end of the toilet flange over where you have marked the holes will go, and trace around the edge of the flanges with your sharpie.
Now drill small pilot holes at some point along the line you have traced with the sharpie, and begin cutting from the pilot hole with the jigsaw. Be careful during this stage, and go slow with the jigsaw to prevent the container from cracking. If the container does crack, it’s not a huge deal as you can seal the crack with silicone when finished.
After you have drilled both holes, take the toilet flanges and insert the THINNER side of the flanges into the holes.
Now get your drill again and using the ¼” bit, drill 4 holes through the plastic container using the ¼” holes in the toilet flange as a guide, then fasten the toilet flanges to the container using the nuts and bolts and tighten the nuts using the adjustable wrench or ratchet.
Now lay a bead of silicone around where the toilet flange meets the edge of the plastic container on the INSIDE of the container. If your container cracked during the cutting of the holes, at this point you should also lay a bead of silicone over the cracks. Leave the silicone to set for 4-6 hours.
Now get a helper to assist you in holding the SAB while you stretch the rubber gloves over the inner lip of the toilet flange. Stretch the gloves about 1” over the lip of the flange, then apply tuck tape all the way around the flange to secure the gloves. Trying to do this on your own is challenging so we recommend getting another set of hands! Also be cognisant that the gloves are taped on with the palms facing down (or else you will have to twist the glove in order to insert your hand and therefore will lose reach inside the box)