FAQ: Frequently Asked Questions

If you’re just starting out growing mushrooms, you’ll almost certainly have a head full of questions. The most frequently asked questions can of course be googled and you may well find your answers quickly and easily – or you may find a dozen different answers to the same question. In many cases, all the answers will be correct (to one degree or another) as growers eventually develop ways of working and techniques that work for them and the particular mushrooms they grow.

We’ll try answering as many of the most frequently asked questions below – for convenience we’ve tried categorising questions into logical groups.

General Questions

These are frequently asked questions we couldn’t find a category for..

Absolutely yes.

There are many different levels, different ways to be involved with growing mushrooms and at the most basic level – buying a simple ready-to-go grow bag which requires you to do little more than find a shady spot for your grow bag and spray it with water as it grows – it barely involves any serious effort and absolutely no special equipment.

If you want to be involved in more aspects of mushroom cultivation, you might want to buy various bits of equipment to help you. If you want to be involved with all aspects of mushroom cultivation from developing spores into mycelium onwards, you might want to have a room you can reserve for that purpose and you’ll need to buy more equipment, but there’s very little that can’t be done at home.

Mycelium is the first stage of life for the mushroom organism. It develops from mushroom spores and grows into a white mass that you might think looks a bit like a cross between a trippy spider’s web and mould. It forms a mass from strands of what are called hyphae, which you might say look a bit like roots, and this mass is what makes the magic happen by breaking down and consuming nutrients via the excretion of enzymes. These nutrients are absorbed and used to expand and eventually produce fruiting mushroom bodies. Mycelium have different appearances depending on the type of mushroom, so Oyster mushrooms produce thick, white mycelium, while Lion’s Mane mycelium is much finer and less opaque. When grain or substrate is colonised by mycelium, the block will be visibly encased in a layer of mycelium.

Probably the most common mistakes relate to things that are mentioned throughout this website:

Sterile working – it isn’t optional. Grabbing a cloth out of the sink and wiping surfaces down might do in a general sense, but not when you’re working with mushrooms. Having an OCD cleaning obsession will not hurt you even a little bit!

Rushing – mushrooms and mycelium hate impatient people. Everything needs to be done carefully, things like allowing things to cool down can’t be forced. Opening a pressure cooker too soon can suck contaminated air in, inoculating spawn before it has cooled down will only cook your mycelium, and so on. Take your time and be patient.

Remember value for money – cheap is rarely the best option. Example; there are countless cheap mushroom bags available for sale all over the internet. They were shipped here from China yet still cost a fraction of what high quality bags do, and there’s a reason for that. Shoddy construction that will see you split bags without too much trouble, filters of an unknown quality and so on. If you need cheap, fair enough, but good quality equipment and supplies will last longer, provide better results and cost less in the longer term. The same applies to things like laminar flow hoods, incubation chambers for petri dishes and liquid culture, decent impulse sealers for bags and so on. Even if growing mushrooms is a hobby, investing wisely always pays.

Ignoring environment suitability – read up on the conditions your chose mushroom needs in order to grow properly. Provide those conditions – whether that’s temperature, amounts of light, humidity levels and air exchange requirements. A bit like having a pet, Great Danes don’t generally eat rabbit food (yes, they’re about as smart as a dandelion and doubtless one or two will give it a go, but still….) and amazonian snakes rarely survive long if kept in an unheated garden shed.

Not being methodical – find a technique and method of doing everything. Write it down if you’re liable to forget, and follow it. If you make a mistake you can backtrack and work out what it was, and avoid it in future. Label everything you do – when each batch of agar was made, and with what. When your substrate was prepared, what liquid culture you incoculate with and the date (so you can learn how quickly results should appear. And so on.

All sellers have their own way to describe what are loosely termed mushroom ‘grow bags’. Reading the description fully is important as different sellers will describe the same thing in different ways.

In essence, this is what you will find on sale online:

‘Ready to go’ grow bags. These are usually supplied by businesses which sell mushrooms as opposed to equipment for mushroom growing. They’ll be described as being already ‘inoculated’ or ‘colonised’ or ‘ready to fruit’. These bags will already have been inoculated with liquid culture or spores (think of this as having the seeds already planted and germinated) and will generally be supplied as a special polythene bag encased in a box which you partly open. Apart from spraying the contemts of the box with water regularly, there’s little you need to do with these boxes. ‘Ready to fruit’ is probably the phrase to look for, as well as being asked at the time of ordering what type of mushroom box you want to order.

‘All in one’ and ‘Grow bags’. These are normally bags which contain sterilised grain and substrate (a bit like soil) to which you need to add liquid culture or spores. One or two we’ve seen also include your choice of liquid culture syringe, but not many. These bags generally don’t contain or include liquid culture or spores and are in effect a blank canvas. You then need to find and buy the liquid culture which has to be injected into the grain to kick-start the growing process. The bags will also have different substrates – which will suit different types of mushrooms. It’s worth asking the seller which mushrooms the bags are suited for if you don’t already know.

You should also check that the contents are already sterilised, as we’ve also seen some sellers who supply ‘kits’ that haven’t already been prepared – some substrates will need to be sterilised, some will need to be pasteurised. If you don’t know how to do these things, go for a kit that is ready to go.

Cordyceps – Cordyceps Sinensis to be precise. Cordyceps is a type of edible fungus (all mushrooms are fungus) with several hundred different strains which occur naturally, mostly in Asia. They’re undoubtedly one of the most unusual organisms you’ll ever come across and one strain (Cordyceps Sinensis) was the basis of the parasitic fungus which featured in HBO’s series ‘The Last of Us’ and is sometimes called the ‘zombie ant fungus’ because it infects and grows on ants and other insects and pupae!

Despite what you saw in ‘The Last of Us’, Cordyceps Sinensis can’t infect humands and can’t even be grown at home, so any ideas you had of infecting unpopular neighbours aren’t going to work.

Frequently asked Questions – Contamination

If you read anything, almost any article at all about growing mushrooms, you’ll already be aware that contamination and avoiding it is something you need to learn about. The articles or posts you’ve seen about contamination refer to unwanted spores and bacteria that can enter and take over, or kill, your mushroom grow. You could equally think of it as pollution, if it makes more sense to you. Here we’ll try to cover the most frequently asked questions relating to contamination as it relates to home mushroom growers.

Contamination, as it relates to mushroom growing, refers to unwanted spores and bacteria which find a way to enter your spores, liquid culture, grain spawn, grow bags, substrates, monotubs and anything else used during the process of growing mushrooms. Typical consequences of contamination might be an invasion of green (or other coloured) mould starting to take over your growth, cloudy liquid culture, wet and soggy-looking spawn and unpleasant smells.

Yes, airborne contaminants are always an issue, not least because because you can’t see them and air gets absolutely everywhere!

Mushrooms reproduce via spores, which you could think of as being seeds. These spores are microscopic, falling from the mushroom when it’s time to reproduce and are usually dispersed in the air. But air distribution is also how many other competing organisms, moulds and bacteria reproduce.

In an ideal world, the best way to reduce contaminant spores and other airborne contamination would be to use a laminar flow hood, which is effectively a workbench-top fan which incorportaes a HEPA (High Efficiency Particulates Air) filter and which blows cleaned air onto your workspace. A flow hood is expensive and many can’t justify the cost (or even the space required) so the next option would be to use what is called a ‘still air box’. A still air box is essentially a transparent plastic tub with a lid, into which armholes are cut which allow you to work in the protected air inside (closed and usually inverted) tub.

Without either of these items, the best thing to do is work within a closed room which has had all heating turned off for at least an hour beforehand, and in which the air has been undisturbed for at least that length of time. This allows as many airborne contaminants as possible to drop out of the air.

Absolutely, yes! Our human bodies are one of the greatest sources of contamination for mushroom growers. No matter how clean we imagine ourselves to be, our hands, clothes, hair and breath contain enough bacteria and spores to ruin any crop. The risks this presents can be reduced by taking a shower before starting any work, and always using hand sanitiser. Wearing freshly clean clothes, (even a lab coat) will help, along with wearing one of the mountain of covid facemasks you have lurking in the house and also disposable lab gloves. Due to bacteria in our breath, it helps if you don’t speak while working, especially near open containers such as plates, jars, or exposed substrate or grain.
The most common signs of contamination vary according to what they affect but in general are:
Unexpected appearance of different colours: For example blue-green, yellow, orange or brown on the surface of mushrooms or growing medium.
Smells: a strong unpleasant odour coming from your growing containers or growing medium.
Abnormal growth: Mushrooms that grow abnormally, such as those that are misshapen or stunted.
Insects: insects, such as flies or mites appearing on the substrate or fruiting bodies.
Cloudy or miscoloured liquid culture, often with darker coloured spots within the mycelium.

The most common signs of contaminated liquid culture are listed below. It’s worth noting that these signs can be harder to see when liquid culture is in a syringe.

Visual Changes in the Medium

  • Cloudiness: Cloudiness often indicates bacterial or fungal contamination. Liquid culture should be clear.
  • Sediment: Contaminants may settle at the bottom as visible clumps or debris and can be seen after gentle stirring.
  • Colour Change: Unexpected color shifts in colour can indicate microbial growth or pH changes caused by contamination.

Unexpected Growth Patterns

  • Floating Layers: Fungal moulds and some bacteria can form a layer on the surface.
  • Clumps: Competing fungi or bacteria can form visible clusters.

Odour

  • An uncharacteristic smell can indicate microbial contamination, particularly bacteria or yeast.

Presence of Mold or Fungal Spores

  • Moulds can display fuzzy or stringy growth, generally where the air and liquid meet.

Common signs of contamination in grain spawn

Unusual Colours:

  • Green Patches: Often caused by moulds like Trichoderma. These green spots are usually the most common contaminants.
  • Black, Blue, or Grey Spots: These can indicate different moulds (Aspergillus, Penicillium, or others).
  • Pink, Orange, or Red Growth: These can indicate bacterial or fungal contamination (Neurospora or yeasts).

Unpleasant Odours:

  • Sour, Sweet, or Fermented Smell: Indicates bacterial contamination, commonly referred to as “sour rot.”
  • Rotten or Musty Smell: Can indicate a fungal or mould contamination.

Slimy Texture:

  • A slimy texture on the grain indicates bacterial infection, often due to excess moisture.

Discolored or Weak Mycelium:

  • Greyish or Transparent Mycelium: Could indicate competition with moulds or bacteria.

Common signs of contamination in substrates

Colour Abnormalities:

  • Green Mould (Trichoderma): Commonly starts as white but quickly turns green as it sporulates.
  • Blue or Black Mould: Indicates spore-producing moulds like Aspergillus.
  • Yellow or Orange Areas: Could be caused by bacterial colonies, yeast, or chemical reactions (e.g., “wet spot bacteria”).

Bad Odours:

  • A substrate should smell earthy or neutral. A sour, sweet, or putrid smell signals contamination.

Unusual Texture:

  • Slimy Patches: Often associated with bacteria.
  • Dry, Brittle, or Powdery Areas: May indicate contamination by moulds or dehydration of the substrate.

Cobweb Mould (Dactylium):

  • A greyish, wispy mould that has an appearance similar to a fine cobweb which spreads quickly across the substrate, often mistaken for mycelium in its early stages.

Delayed or uneven colonization:

  • Healthy mycelium should spread uniformly across the substrate. Slow growth, bare patches, or isolated clusters of mycelium can indicate contamination.

Blackened or Decaying Substrate:

  • Visible rot or decay in the substrate is a sign of bacterial contamination or excessive moisture.

Avoiding contamination when growing mushrooms should be your primary aim, but you also need to accept that from time to time it will happen, regardless of your efforts. We all make mistakes and things can happen without our knowledge or intent. However, you can significantly reduce the chances of contamination occurring with a little thought, organisation and planning.

By focusing on hygiene, environmental control, and proper techniques, the risk of contamination can be significantly reduced. Here are the most important tips:

Develop and maintain good sterile working practices

Personal hygiene:

  • Wash hands thoroughly with soap and water before handling anything.
  • Wear clean clothes and, if possible, a face mask, gloves, and a hair cover to reduce the introduction of contaminants.

Clean work area:

  • Disinfect surfaces, tools, and containers with alcohol (70% isopropyl) or bleach solution before starting.
  • Use a still-air box (SAB) or a laminar flow hood (if you can afford one) to work in a sterile environment.

Flame sterilization:

  • Sterilize needles, scalpels, or other tools with a flame until red-hot before use.

Proper Grain and Substrate Preparation

Grain Spawn:

  • Ensure grains are properly hydrated but not overly wet (grains should feel firm but not mushy or leaking water).
  • Sterilize grain jars (if used) thoroughly in a pressure cooker at 15 PSI for 90 minutes.

Substrate:

  • Use high-quality, contaminant-free materials like coco coir, vermiculite, or hardwood sawdust.
  • Sterilise wood-based substrates in a pressure cooker at 15 PSI for 90-120 minutes.
  • Pasteurize CVG substrates to kill contaminants while preserving beneficial microbes.

Choose clean spawn sources

  • Purchase grain spawn or spore syringes from reputable suppliers to ensure high-quality, contaminant-free starting material.

Control Environmental Conditions

Temperature:

  • Maintain optimal temperatures for your species (e.g., 18–23°C for most mushrooms). Higher temperatures promote bacterial growth.

Humidity:

  • Use a clean, well-maintained humidifier or misting technique to maintain humidity without making surfaces overly wet.

Airflow:

  • Ensure adequate fresh air exchange (FAE) while avoiding exposure to airborne contaminants like mould spores. Use HEPA filters if possible.

Monitor moisture levels

  • Overly wet conditions encourage bacterial contamination. Grain and substrates should be moist but not waterlogged.

Regular inspection

  • Check grain spawn and substrate daily for early signs of contamination:
  • Check for odd colours (green, black, pink, orange).
  • Check for bad or sour odours.
  • Check for slimy textures or unusual growth patterns.
  • Remove contaminated materials immediately to prevent spread.

Proper handling of spawn and inoculation

  • Work quickly and confidently during inoculation to minimize exposure.
  • Avoid shaking or handling grain spawn excessively after inoculation, as this can distribute contaminants.

Clean and maintain equipment

  • Regularly clean tools, containers, and workspaces. Disinfect reusable materials like jars and lids thoroughly between uses.

Use a controlled growing environment

  • Keep your grow area clean, free of clutter, and away from sources of contamination like household waste, pets, or mould-prone areas.
  • Where children are present, warn them not to touch anything!
  • Avoid high-traffic areas where airborne contaminants are more likely.

Be Patient and Stay Observant

Rushing the process (e.g., inoculating jars before they’re cooled, skipping sterilization steps) can lead to contamination.
Monitor conditions like temperature and humidity consistently and make adjustments as needed.

Discard any contaminated items promptly

  • If contamination occurs, isolate and discard contaminated jars, bags, or substrates in sealed plastic bags.
  • Sterilize the area and equipment before starting a new grow.

By following these practices, a novice grower can greatly reduce the risk of contamination and set themselves up for success in mushroom cultivation.

Frequently asked Questions – Mushroom Substrates

Mushroom spawn is a substance that has been inoculated with mushroom spores or liquid culture to serve as food and home for mycelium to grow in, prior to developing into mushrooms. It can be explained in a much more scientific manner, but that’s the essence of it.

Most of what you find online will refer to ‘grain spawn’  and grain spawn will relate to the grain (such as rye, wheat and so on) which has been injected with either spores or liquid culture to begin the mushroom growth cycle by developing mycelium. It can also be used in a generic way to describe the grain itself – for example when talking about what grain should be used in the process.

Mushroom spawn can be a multitude of materials and before deciding on which you want to use, you need to read up on the type of mushrooms you want to grow and learn what materials they like best.

As per the previous question, the answer depends mostly on what type of mushrooms you intend to grow, as some grow better on one type than another.

That said, and speaking in general, many growers swear by rye grain (can also be called rye berries). Other popular choices are wheat, millet (cheaply available and often supplied as a bird food), brown rice and some even use popcorn! Depending on mushroom types you can also use straw, rice flour, cardboard, logs, hardwood sawdust and hardwood wood chips. Some will be ineffective for the mushrooms you want to grow, so read up on your chosen mushroom type first!

As per questions about mushroom spawn, the best substrate to use with your spawn material depends on the type of mushroom you want to grow – and then depends on the type of spawn you choose to use. Different growers will have their own preferred substrate, which is invariably a mix of different materials. The thing to remember is that the majority of mushroom species can be divided into ‘wood-loving’ and ‘maure-loving’. Most mushrooms grow in the wild on dead wood, straw, other decaying organic material or manure. This has a bearing on which substrates and spawn to use.

A quick look online will throw up countless references to CVG substrates. It seems the most popular choice, but the apparent popularity of these references is inflated by the number of people growing magic mushrooms – as CVG substrates are considered to be among the best for that purpose. CVG is also suitable for growing button or portobello muchrooms when paired with a grain spawn.

Mushrooms such as Oyster (in particular), Lion’s Mane and Enoki generally do well in a 50:50 mix of hardwood pellets and soy hulls (some will add small amounts of bran to further supplement the mix). Many wood-loving species will grow well on a hardwood sawdust based substrate and there are many different recipes out there, generally supplemented according to your target mushroom species.

It all boils down to you reading up on your chosen type of mushroom and what they grow best in.

CVG substrate is a mushroom substrate which consists of a mix of Coco Coir, Vermiculite and Gypsum. Although it can also be used for button mushrooms, it is most widely used as a fruiting medium for growing psilocybin mushrooms.

The simple answer is ‘Yes, it should’…. but you probably want to know which one is better! In that case the answer depends on what you want it for:

Making Grow Bags
If you’re preparing grow bags including grain, STERILISE, full stop. In this case, you put your substrate and grain into a mushroom bag together, sterilise it in your pressure cooker and seal it once cooled down. That’s how that should be done.

Bulk substrate for monotubs (etc)
When you’re making substrate to add to colonised grain spawn, you can choose which path to follow.

Pasteurisation
Many growers will say that CVG (coco coir, vermiculite and gypsum) only needs to be pasteurised, and this is correct. Many successful home growers will tell you that they follow a simple ‘bucket tek’ (a silly name that means use a bucket). You’ll learn that everything mushroom-related has to be a ‘tek’ as this makes it sound very complicated….

The process followed is rather unscientific, in truth, but effective enough. Mix your coir (break up any lumps in advance) and vermiculite, add the gypsum to boiling water (mix it well to avoid silt in the container) then pour it over your coir/vermiculite. Stir to mix thoroughly, firstly to ensure the mix is evenly hydrated and also to make sure the vermiculite is evenly distributed, then leave in your sealed bucket for 2-4 hours (depending on who you ask). You can optionally wrap the bucket in towels to try to maintain the temperature for as long as possible. As an alternative, you can do the above as directed, then place your sealed bucket inside another bucket (can be open-topped) which contains hot water (around 70C) , which will keep your substrate at a higher temperature for longer. The most important part of the whole process is to make sure you use the right amount of water as substrate that’s too wet or too dry is bad news.

It must be said that this process works almost all the time and there is no specific reason to use a sterilisation process for CVG.

Sterilisation
The above will tell you sterilisation isn’t actually necessary. Some will also say that some gourmet mushrooms prefer pasteurised substrates over sterilised – that may or may not be a fact but we’re doubtful. In any case, none of this means you can’t or shouldn’t sterilise. It’s your choice. If you’ve had past issues with contamination and want to be on the safe side, sterilising your CVG is a perfectly good option.

There are many types of mushroom which grow best on a wood-based substrate. Most wood-based substrates are made of either hardwood pellets or hardwood sawdust (generally supplied as compressed pellets). Very few mushrooms like softwood. It’s worth reading up on the specific type of mushroom you want to grow, as some are quite picky about what types of wood they’ll grow (well) on. Some prefer oak and so on..

Frequently asked Questions – Sterile Working

If you’ve read anything about growing mushrooms you’ll have come across many references to sterile working, both general and specific. Here we’ll try to cover the most frequently asked questions.

A laminar flow hood is a relatively simple construction; it’s a box which houses a fan, either a squirrel-cage type blower on top of the box or an axial fan at the rear. The fan draws air out of the room and blows it into the box. The air is then forced to exit at the front onto your workspace through an air filter – a HEPA H14 is the recommended type. The HEPA filter removes particles and potential contaminants from the air down to 0.02 micron in size and so washes your working area in clean and non-turbulent air.

To be suitable, a laminar flow hood needs to blow a steady stream of clean air over your workspace. It should provide a measurable air flow of 100 feet per minute (or more if it has a way to adjust speed). The airflow needs to be smooth and not turbulent. Totest a working hood, hold a flame in front of the hood and see what happens – the breeze should bend the flame at a fairly constant angle – the same applies with a lit joss stick – the smoke should trail away in an even flow.

To provide clean air, the flow hood needs a HEPA filter, ideally type H14. H13 can be used but isn’t as effective – and as filters are used they become less effective, so it’s best to start with a more effective filter in the first place to allow for this.

Whatever type of flow hood you find, check its claimed performance and specs before you buy. If it doesn’t mention filter type (many say little more than ‘filter’ or sometimes ‘hepa’) ask. If it doesn’t specify air speed, check. If the seller can’t tell you, they have no genuine idea if what they are selling is suitable. If they quote an airflow speed, as how it was measured. The kind of digital anemometer 9wind meter) you find on amazon is not suitable for measurements as they’re notoriously inaccurate, particularly for low wind speeds and 100 feet/minute is only about 1.1mph.

Sites like Amazon are flooded with countless small flow hoods, sometimes so small you wonder if they were made for a child’s hands. You’ll find the same photos used over and over again with numerous “brand” names. These cheap imports from China carefully avoid mentioning filter types, airspeed and anything else you might want to know. Generally, we’d say run like hell. Even the sales blurb only says they’re for working on mobile phones.

Genuine scientific hoods made for lab work will cost north of £1000 new, but you can find custom-made laminar flow hoods made by mushroom growers (we make our own too). The smallest ones are generally 12″ x 12″, but in reality most work requires a larger hood/filter of at least 24″ wide and ideally the same height. A 24″ x 24″ laminar flow hood will typically cost anywhere from £600-£700 depending on the filter and fan type used (H13 filters are not quite as effective but are a bit cheaper). Depending on what you want to do, a larger hood, perhaps 36″ x 24″ would be more suitable. If you’re unsure, find a table top and lay out a reasonable number of containers, petri dishes, slants or whatever you expect to work on. Don’t stack things behind each other as they are blocking the airflow. Now work out how much actual working space you have, or need. It won’t be 12″ wide……

A still air box is a way home growers can get around not having a laminar flow hood but still have a fair chance of reducing the risk of contamination when working with spores, liquid cultures, agar and other related tasks. In essence, a still air box is a transparent plastic storage tub (generally used upside down with the lid attached) with holes cut into the sides to allow you to put your hands inside it and do work inside the box.

The purpose of a still air box is to provide a workspace inside which the air is still – not moving at all or very much. If air isn’t moving, the risk of airborne contamination landing on your work is reduced.

You’ll usually find two different types available:

Basic (often DIY) still air boxes will have two armholes cut into them. That’s about it.

Glove boxes, or sealed (still can be DIY) still air boxes will have two armholes cut into them, around which ports have been attached which hold long-sleeved gloves. The idea is that after loading your still air box (and allowing the air to settle inside) you then put your arms into the gloves and work on your materials without outside air being able to enter. This type of box should offer much higher levels of protection than the basic type.

In relative terms and provided care is taken in how they are made and used, still air boxes will reduce the risk of contamination landing on whatever materials you are working on. Some growers have used still air boxes with excellent results and swear by them.

Effectiveness is down to you and your working/sterile techniques but, all things being equal, sealed glove boxes can be a little more effective than basic unsealed boxes (with just armholes cut into them). Regardless of which type, the insides and all the items you work with must be properly cleaned…

Unsealed still air boxes: These have armholes cut into the side of the still air box. The holes need to be large enough for you to get your arms inside and move sufficiently while working. If the holes are too big they allow air to enter even with your arms inside them. If they are too small they may prevent comfortable working and as you squeeze your arms in or pull them out, they will create an opposite airflow as you move your arms – potentially sucking air in every time you move your arms in an outward direction. As long as they are used with care, still air boxes can provide a safe workspace for working with agar, inoculations and so on, always assuming your sterile techniques are good.

Sealed Glove Boxes; these have similar holes cut into them but the holes have ports attached to them which clamp long-sleeved gloves in place. When using the box you push your arms into the gloves and can work without the risk of outside air being blown or sucked in and out of the box. Upgraded glove boxes will have a small air filter attached over another hole in the box to allow for filtered air to move in and out of the box, balancing air pressure changes as you push your arms inside the box. All being equal, these can be more effective than unsealed basic still air boxes, assuming your sterile techniques are good.

The best way to clean work surfaces and many items you work with, 70% Isopropyl Alcohol and (large) Alcohol wipes are your friends. Simple cleaning with soap and water is always a good idea first, to get rid of as much as possible from surfaces, but it is the alcohol that will do the job properly. Although you can 90% Isopropyl Alcohol, 70% Alcohol is, oddly enough, more effective at killing contaminants. There is an explanation as to why and Google will find it for you, but all you need to know is 70% alcohol is best.

The simple answer is yes you can. Sterilisation occurs at 15psi, just the same as you sterilise substrates and so on, although depending on the items, 15-30 minutes is usually all that’s needed. Most items need to be wrapped in tinfoil before putting them into the pressure cooker; firstly to keep them safe, secondly to keep as much water off them as possible and finally to allow you to take them out afterwards without exposing them to unsterile air. Pressure cooking at 15psi is basically ‘autoclaving’ items. Autoclavable (able to be sterilised at 120c or higher temperature) is a term you need to be familiar with.

Beware:

Not everything can be sterilised. Plastic petri dishes, for example. Some can be autoclaved (pressure sterilised) and some will turn into molten plastic sludge which will ruin your pressure cooker. Some cheaper types of glass can’t be autoclaved either. They can shatter. No container should be closed tight when sterilising – it can cause them to explode with pressure – and instead lids on things like mason jars should be only about 75-80% tight, with tinfoil wrapped over them to protect them.