Flask Sterilization
 

Hey Hey!

So my Seedpod might be ready any day and i need to make some flasks with medium.

I have some problems with sterlize them. :c

I know you can use a pressure cooker/autoclave to get it to 125 °C or something like that. But i do not really want to spend the money on one and im a lil bit scared of them.

There is the debatable microwave option wich as i read works but doesnt. So i dont think i can make that work with my microwave. x.x

So i catched up a method with steaming it in a wok like chinese buns but i doubt it will reach 125°C in there. And i dont find the source anymore sadly.

A normal waterbath like with jams wont work either probably. :/

I dont really have any fancy chemical fumes to serilize either (just H2O2 12% and Isoprop 90%)

sooooooo im out of ideas what to do really. Is there any method you guys know for low budget and a relatvely high succes rate (low conatmination rate)? :3

Thank youuuu~

I will leave it to members who do flasking to advise on what might work for you. But as far as temperature is concerned, the maximum temperature that can be achieved with boiling water at atmospheric pressure is 100 deg C at sea level, lower at elevations above that. To get higher temperatures you have to be able to raise the pressure (which is where the pressure cooker comes in). You can't get around the laws of physics and chemistry...

I wish i could sometimes tho TT

Well cant i just not heat up the air with an oven? Does it has to be a waterbath?

You can heat the air in an oven, certainly. I don't know what the extra heat will do to the medium, or where the limits might be. I leave that discussion to people who actually do this.

You can't heat liquid medium in a hot oven because it will evaporate. Inside an autoclave or pressure cooker the environment is 100% water vapor, and the liquid being sterilized will not evaporate. Powdered media will decompose if heated too high when dry.

Boiling water does not reliably kill fungal nor bacterial spores. The temperature must be higher. So it is useless to sterilizes the dry items in the oven, then add boiled water.

Electric pressure cookers do not get hot enough to sterilize. Only stovetop pressure cookers do.

If you're talking just the glassware, 10% household bleach in water will work fine.

If you're talking plating medium in the glassware, a pressure cooker is the most reliable at-home methodology.

You could try the microwave method and add Plant Protective Mix from Plant Cell Technologies and gentimiacin or some other standard antibiotic used in tc. This would give you some protection and might see you through without the need for a pressure cooker (I gather they’re tough to source in Europe). Another method would be chlorine gas sterilization as posted in this sub. Very Easy Sterilisation Method - My Seedlings

For discussion sake, steam is used to sterilize tools, media, etc. as it contains much greater energy than hot air or water due to the principle of latent heat/energy (of vaporization in this case)…it’s not the temperature that is the key, but the energy…look it up for an actual definition but the gist is that steam contains all the energy required to convert the water to steam. When the steam condenses on the load (tools/media), that energy is transferred to it. Anyone ever blasted with steam can attest to what serious damage can result from very minor contact.

Are stovetop pressure cookers hard to buy in Europe? Kuhn Rikon in Switzerland makes them. At one time a Spanish company called Fagor made them, but I think they are no longer business.

Well they are not that much used here. There are some, sure. But since i am a student, my financial options are limited you know. The cheapest one i found that was big enough for the flasks were like around 100€.

They are not really hard to find but very expensive most of the time.

---------- Post added at 12:16 PM ---------- Previous post was at 12:12 PM ----------

I saw that methods already but they are too complicated to do here. Germany is a little more restrictive with stuff and sewing orchids is not really a big thing here. So resources and lab stuff that you can get as a private person are limited. (also as plant antibiotics)

Thank you for explaining! I understand now that its not due to the water but the energy itself. Makes a lot of sense actually xD

The killing of organisms by heat relies on all the material being exposed to a predetermined temperature for a predetermined amount of time. How long it takes to kill various microorganisms and their spores at various temperatures is well studied, and this information has led to standard autoclave protocols.

How the temperature is achieved, or how the energy is conducted to the material to be sterilized, does not matter.

The temperature needed is above the boiling point of water at sea level. To achieve higher temperatures than the boiling point with water, it must be contained in a sealed vessel, or the steam will escape at ambient atmospheric pressure as it is formed. So, if water is to be used for sterilization, it must be in a sealed vessel under pressure.

Almost all solid have microscopic cracks and pores in which spores may lodge. Dry heat penetrates unevenly into these small cracks and pores. It may take many hours for these cracks to reach the desired temperature, and it is impossible to determine when that occurs. So dry heat is unreliable for sterilizing solid objects.

Steam is able to penetrate all these cracks and pores, and we can use steam under pressure to achieve the higher temperatures needed. These two factors are why it is used for sterilization under pressure. It is certainly true steam carries much more energy than air at any given temperature, but this is not the reason it is used in sterilization.

If you say so. Nice copy pasta, btw.

I wrote that myself. It was a first draft. It's standard teaching. I was doing bacteriology research in the mid 1970s. Autoclave technology was already old then.

My point was that steam is more efficient than air at sterilizing things. You had to “correct” me by pointing out that steam is more efficient than air at sterilizing things.:lol:

Though a bigger pressure cooker might be preferred, smaller pressure cookers are often available for less than $50. In fact, Amazon in the US lists over a dozen models for under $40. One may consider multiple runs to sterilize what needs to be done.

Yeah, might be. Here in germnay they are mostly a lil more pricey.

Also "just" buying a cheaper smaller one is as you said not that smart. I dont wanna wait 40 mins for every single flask xD

Fortunately, i could lend one from my grandma~

It will vary with the specific flasks used, of course, but a typical household pressure cooker can hold about 5-6 flasks per layer and a couple of layers can be done, using a metal separator.

They need to be treated 15-20 minutes.

Well i use standard jam jars. Theres no space for more.

And yeah you are right up to 20 mins. But without cooldown and heating up to the pressure.