How To Use Parafilm

This guide will show you how to use parafilm for mycology enthusiasts wanting to get into agar work.

This is what we are going to learn how to use:

What is parafilm?

Parafilm is a versatile laboratory film used to create a barrier or seal in scientific settings. It’s made from a blend of waxes and polyolefins, providing stretchability, flexibility, and moisture resistance.

Why use parafilm?

Parafilm is fantastic stuff. It is a film that you can use to seal up your petri dishes that prevents any nasties from getting in while remaining breathable. After working hard to keep your agar work free of contaminants the last thing you want is for something to get in there and ruin it. Benefits of using parafilm include:

Contamination Prevention: Parafilm serves as a barrier against airborne contaminants, bacteria, or other fungi, safeguarding the integrity of the fungal cultures.
Moisture Retention: It helps maintain the necessary moisture levels within the agar plates, creating an ideal environment for fungal growth.
Easy Handling: Parafilm’s self-adhering properties and flexibility make it easy to apply and mold around the petri dishes, ensuring a secure seal.

As you can see parafilm is an indispensable tool in every mycologist’s arsenal!

What do I need to start using parafilm?

To start using parafilm you will most likely need the following as a minimum:

Parafilm – You can buy this here.
Petridishes with agar
A still air box or flow hood
Something to go on your petri dishes such as a liquid culture

How to use parafilm to wrap a petridish

We will assume you have set up your work space adequately and are following clean technique when carrying out the following steps. It is always best to make sure you have everything to hand and prepared before starting any mycology work to reduce the chance of contamination.

1) Cut Parafilm: First of all you need to cut your parafilm to the required size. It has been conveniently marked out so you just have to follow the blue lines. We are going to go two squares across like so:

2) Remove Backing And Fold: I like to take the film, remove the backing, and fold it in half along the long edge like this:

3) Wrap Petridish: Now we are ready to take our petri dish and start wrapping the film around. Be concious of what you have inside your dish as you probably want to keep the dish flat while wrapping it up so the contents don’t go everywhere. The film stretches so if you start by pinning the end down with your left thumb you can pinch it with the thumb and forefinger of your other hand so the tips of your thumbs are touching, and then pull it about 3-4cm while wrapping it around the agar plate. You can definitely over stretch it and it will snap so err on the side of caution. Stretch, attach, stretch, attach, going all the way around the rim of your agar plate. Think of it like stretchy clingfilm.

4) Seal Petridish: Once you get all the way around there is usually a small overlap which is ideal for making sure the dish is completely sealed and also indicates you are stretching the parafilm the right amount.

How to store your petrishes after using parafilm

Your petridishes will be fine at ambient temperature for about 1 month. You can also keep the petridishes in the fridge but I would consider checking for contamination and moving your agar to a fresh plate every 6 months or so.

And that’s all there is to it.

Happy Mushrooming!