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Making Airport Style Lids

Airport style lids are foundational for any mushroom cultivation practice. They were developed by Hippie3 on the website Mycotopia and can be used for a variety of applications like liquid culture, grain spawn, or fruiting substrate work. For fruiting substrate jars, this "airport" lid is a little modified and you do not need to make the silicone injection port.

To make airport style lids you drill 2 holes in the lid of any sized canning jar you'd like to experiment with. One hole will be filled with polyfil and used as an air filter. The other hole will be filled with a dab of high temperature RVC silicone, used as an injection site so that you can cleanly inject or extract what's in the jar by using a syringe needle. This silicone port site is self-healing and this whole jar and lid setup is pressure cooker safe.

I definitely make at least a handful of jars at one time as a part of streamlining the cultivation process. Watch the accompaniment video here!

Wide neck 36 oz. mason jar with airport style lid.

Underside of "airport style" mason jar lid. What you need:

  • Polyfil (the stuff that's inside of teddy bears).

  • High temperature RVC silicone.

  • Any size WIDE mouth mason jars with lids (any size -- but I use 34 oz. and 24 oz. for grain spawn and fruiting substrate).

  • Drill with drill bits -- 1/4" and 3/16".

How to make an airport style lid:

1. Drill a 3/16" hole in the mason jar lid 2. Drill a 1/4" hole in the mason jar lid. a. Drill tips: I keep my lids twisted onto the mason jar to make drilling easier. b. Once you've penetrated the lid, rotate the drill bit in a circular way to try to smooth out the edges. When you're done drilling holes you might want to drill down any spiky metal edges that were made in the process of drilling holes with either the drill bit or by pulling them off with tweezers. 3. Pinch off a chunk of polyfil, twist it up a bit, and push a bit through one side of the 3/16" hole while pulling through on the other side. You want the polyfil to be very snug so that if you try to pull on one side there is hardly any give. a. My fingers usually always bleed a bit during this step as they get 1 or 2 tiny cuts by the sharp metal edges -- you can ground these down as best as you can in Step 2. 4. Now that the polyfil is added, apply the high temperature RVC silicone on the 1/4" hole you've drilled. a. I do the silicone last so it can dry without being smudged by pinching the polyfil in. Apply a ball of silicone on one side and then smooth out the edges to make them as flush with the mason lid as you can. Then flip the lid over and smooth out the other side -- you might also have to add a dab on this side. The idea is that this port is smoothly connected to the lid, on both sides, so that the silicone has less of a chance of popping out of place, tearing, and opening up any holes for contamination. 5. Wait for the RVC silicone to dry over night. Congrats! You have airport style lids. Wash the jars out before use. You can use these reusable jars in your pressure cooker until they break down or until the glass shatters, which will hopefully be in a long, long time.

To make a "modified" airport style lid to use with fruiting substrate you only drill one 3/16" hole in each mason jar lid and pinch some polyfil through. There is no need to make a second hole for the silicone injection site, since you don't use this to expand from grain spawn to fruiting substrate. Though, it doesn't hurt to have a bunch of jars lying around that have this feature.

Hope you dig! If you have any questions or comments please reach out to Gabriela at This article was originally published May 17, 2020 on

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