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Cant get collapsed bags by end of pc cycle
    #25568482 -

Hi everyone,

I am having a lot of issues with contaminated grain bags I am trying to produce myself. I assume the problem is occurring because i am getting contaminated air inside my autoclave when I equalize the pressure to open it. I base this on the fact that I am inoculating stuff in front of a flow hood (so the inoculation process should not be an issue), and also on the fact that the bags are never fully collapsed by the end of the cycle (as if they were pulled inside by some kind of vacuum) as I see a lot of people are able to do in their pcs (that also happens in RRs videos). Furthermore, the contaminations are always on the top of the bags, so this not most probably not due to a too short sterilization cycle. Finally, to further corroborate my suspicion, I have been able to make 20 agar plates with zero contaminants, whereas I get about 80% contamination in my grains bags (I think this, again, indicates my flow hood is not the problem).

So I was wondering what I could do to make my bags fully collapsed at the end of the sterilization cycle. What I usually do is turn of the heat and just walk away, and them some 24 hours later i am able to open the valve to let air in. Should I vent the autoclave at the end of the cycle, and them close the valve to let it cool? Anybody has had this kind of issue?

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Re: Cant get collapsed bags by end of pc cycle [Re: vsoares]
    #25568700 -

How are you folding up your bags? How do you have them in the PC?  Are you running sleeves in them?  Give us some more details. 

Sounds like your getting inflation of the bag.  Happen more often with pre sealing them, or if you have too much space inside the PC.  Also try to get all the air out of your bags before you PC.

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Re: Cant get collapsed bags by end of pc cycle [Re: Tookitooki]
    #25568743 -

Sleeves are supposed to not be necessary and if anything they could prevent contraction of the bags. The bags should shrink if they kinda seal by having folds and something like a rope keeping it tight as a package (or weight on top). If they seal when they cool they can start sealing even better and as the pressure lowers the bags should contract.

It's gotta be the way you prepare the bags?


--------------------
My trade lists:
  • Fungi - Edible / Gourmet
  • Fungi - Medicinal/Insecticides/Bioluminescents
  • Fungi - Actives
  • Fungi - Old Exotic Spores (Actives)
  • Fungi - Misc Hunted Mushroom Spores
  • Plants
  • Other items - Supplies etc.


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    Re: Cant get collapsed bags by end of pc cycle [Re: Solipsis]
        #25568887 -

    I have tried folding the bags and laying them inside the Autoclave in every possible way known to man. I have also sterilized with full autoclave and 2/3 full autoclave. After posting I was thinking more about It, and i realize most folks use polypropilene bags, whereas i have been using high density polyethile bags. I will get some PP bags and run a new test to see if i get different results, thanks guys.

    Edited by vsoares (10/26/18 10:45 AM)

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    Re: Cant get collapsed bags by end of pc cycle [Re: vsoares]
        #25568934 -

    I try to open valve on pressure cooker when it drops to zero.
    If you cooker pulls a vacuum then best to just open at flow hood. If you can't do that wrap alcohol  soaked rag around valve to filter as you release vacuum.


    --------------------

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    Re: Cant get collapsed bags by end of pc cycle [Re: Quadman]
        #25569083 -

    I've run with and without sleeves.  With sleeves I never got ballooning of the bag, and it still pulled a vacuum.  When I don't run sleeves, sometimes the air can't find its way out very well and will inflate the bag and cause it to come in filled to, or if it can't unfold itself, it'll stretch out the plastic.


    https://www.shroomery.org/forums/showflat.php/Number/25367454

    Here's a recent thread from mush cult about the topic that might help.

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    Re: Cant get collapsed bags by end of pc cycle [Re: Tookitooki]
        #25569832 -

    So you are using an autoclave and not a PC. I just want to be clear on that. If you are using a PC then don't do anything to release pressure at all. Let them cool in the PC. The slow cooling will cause a vacuum on the bags and seal them.

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    Re: Cant get collapsed bags by end of pc cycle [Re: SHROOMSISAY01]
        #25574423 -

    I'd bet you seal the bag which is the problem.


    --------------------
    Stop talking about being enlighten. Crybabies, bitches, and people worried about ratings can never reach enlightenment!  NEVER!

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    Re: Cant get collapsed bags by end of pc cycle [Re: Tits on a bull]
        #25578134 -

    Pretty sure you would notice as they would inflate or even pop. Probably makes a mess either way.

    Not sure if the material of the bags is relevant, HDPE should not melt until above 120C and I figure the producer knows they are for autoclaving.
    However the filter patch in the bags must have the right pore size. If not that could explain why you get top contams.

    Do the bags really have to be collapsed? The only thing you clearly don't want is dirty air flowing back in as the bags cool. If there is plenty of air in there this air should just compress from cooling but if there is very little air in there the pressure could drop to the point of sucking in air.
    But if the bags are still folded by having used rope to wrap them, air cannot really pass properly so it seals and contracts causing a small vacuum / collapse.

    People use tyvek sleeves in the folds to try and filter this air. But not everyone agrees on it.

    I used to fold my bags differently but now fold it in a "loop" so that the opening of the bag is wrapped inside and I do use sleeves.

    If you take the bags out of the autoclave when warm and let them cool in open air and the amount of air in there and pressure etc cause air to get sucked in that could be a problem.
    This is why people say leave it to cool in the PC / autoclave.. Lately I have put semi warm bags in cupboards in the hope that there is not a lot of contams floating in the air, and I do use sleeves anyway.

    Do some experiments that thoroughly protect against dirty air.

    It could be wrong bags but I doubt it, I think you are missing one of these steps that ensure that a vacuum is pulled upon cooling and instead you are sucking in dirty air.


    --------------------
    My trade lists:
  • Fungi - Edible / Gourmet
  • Fungi - Medicinal/Insecticides/Bioluminescents
  • Fungi - Actives
  • Fungi - Old Exotic Spores (Actives)
  • Fungi - Misc Hunted Mushroom Spores
  • Plants
  • Other items - Supplies etc.


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    Re: Cant get collapsed bags by end of pc cycle [Re: Solipsis]
        #25578483 -

    So, I have tried the PP bags and the results are the same, I dont get the brick like bags I would want to. I latter thought maybe I wasnt venting the autoclave long enough at the beggining of the cycle, which meant I was having too much air (instead of pure steam) inside the autoclave, which would prevent the formation of a "vacuum" at the end of the cycle. So I vented my autoclave for 20 minutes before the start of the cycle, and the result was exactly the same, which means, not what I wanted.

    I dont seal the bags before autoclaving, i just fold them. Sometimes I make the acordeon style folding. Anyway, it is possibe to see that there is some air inside the bags when I open the autoclave, before even touching them.

    My autoclave does pull a vacuum.

    I have no idea about the pore size of the filter bags, it might be a reason why I am getting contams, but I guess it would not explain why I dont get the brick like bags at the end of the cycle.

    I am trying to get the fully collapsed bags because this way I believe very little dirty air can get pulled inside of them when I open the autoclave. I am running out of ideas....

    Edited by vsoares (10/30/18 11:17 AM)

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    Re: Cant get collapsed bags by end of pc cycle [Re: vsoares]
        #25578630 -

    So your autoclave doesn't dump steam at the end of the cycle?  I have heard this is common and causes busted bags.


    --------------------
    Fiery Fungi (like us on faeboo)

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    Re: Cant get collapsed bags by end of pc cycle [Re: drake89]
        #25578701 -

    I can dump it manually if i open the valve. Maybe thats is the issue? I never tried doing that.

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    Re: Cant get collapsed bags by end of pc cycle [Re: vsoares]
        #25578997 -

    You want a slow cool the slow cool is what causes the vacuum. Same as with a PC.

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    Re: Cant get collapsed bags by end of pc cycle [Re: SHROOMSISAY01]
        #25579218 -

    You do tie them up right?

    Because just folding them may not work since if the bag expands during the cycle it could create an opening for air to pass perhaps big enough to prevent the bag from "choking on itself" like you want and what creates the vacuum.

    You can't look into your autoclave right? Would be helpful to see how the bags behave especially during cooling.


    With liquids like agar you definitely don't want to hasten the cooling because it can overboil, but is there really a problem when doing bags? I can't really think of a way faster pressure drop would prevent the bag from choking on itself and collapsing.


    Have you checked if used bags are still sealed and airtight?

    How full are you filling these bags and can you show a pic of a bag you prepared (and maybe others like of a bag after a cycle and your autoclave)

    What I don't know is if the filter patch allows for such low amounts of air passing that it couldn't play a role in preventing the vacuum collapse.
    In any case it doesn't make sense cause a lot of people have no problem doing this and you have tried it in so many ways, suggesting it is not such a cause as filter patches being blocked or not. But just for good measure: I think in almost all ways of folding the bag the patch should be getting blocked in a flat folded part.

    My suggestion for now is to try it with a weight placed on a bag to help it close and choke during cooling. Try to make sure there is little air left in the bag too.


    --------------------
    My trade lists:
  • Fungi - Edible / Gourmet
  • Fungi - Medicinal/Insecticides/Bioluminescents
  • Fungi - Actives
  • Fungi - Old Exotic Spores (Actives)
  • Fungi - Misc Hunted Mushroom Spores
  • Plants
  • Other items - Supplies etc.


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    Re: Cant get collapsed bags by end of pc cycle [Re: Solipsis]
        #25579231 -

    Trust me slow down the cooling and they will seal. But if you like I can start a tread on thermal dynamics.

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    Re: Cant get collapsed bags by end of pc cycle [Re: SHROOMSISAY01]
        #25579279 -

    My bags collapse fine in a small shitty PC that really doesn't take long to equalize the pressure when i turn off the heat. I definitely don't think that his autoclave is any quicker (without use of the manual valve of course).

    I'm interested in a little physics, can't you just explain a bit what you mean by what thermal dynamics mean for the difference in sealing/collapsing?

    Seems like from the moment the bag seals during cooling the further drop in pressure from the cooling relative to ambient conditions will cause contraction of the bag (probably consolidating the seal). So getting a good enough seal in the first place seems critical.
    I don't really see what happens if you do it very quickly, say near instantly.. hmm.. if there is a good enough seal to start with the same thing should happen.. or maybe if you do it slowly the seal is better because it adds up / consolidates / "crystallizes out" better.

    But still! Getting a good enough seal in the first place to seed this effect seems most critical. no>?

    If physics discussion helps to solve the problem, OP is probably fine with it


    --------------------
    My trade lists:
  • Fungi - Edible / Gourmet
  • Fungi - Medicinal/Insecticides/Bioluminescents
  • Fungi - Actives
  • Fungi - Old Exotic Spores (Actives)
  • Fungi - Misc Hunted Mushroom Spores
  • Plants
  • Other items - Supplies etc.


    • Edited by Solipsis (10/30/18 05:28 PM)

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    Re: Cant get collapsed bags by end of pc cycle [Re: Solipsis]
        #25579377 -

    Sorry I will be a little more careful with my jokes next time. I actually know nothing about thermal dynamics and I actually had to look up how to spell it. What I do know is from experience. I have never opened up my PC quickly but every time I open my 55-gallon steamer right after a cycle is done my top bags are loose but. If I wait for a day or two they are all sealed perfectly. The OP mentioned equalizing the pressure so I assume he is releasing the pressure which is his problem.

    What I believe is happening when you release quickly is the bag cools down much quicker than the spawn and evaporates any water on the plastic and never seals. When you let it cool down slowly it slowly pulls the bag together and does not evaporate the moisture between the two pieces of plastic the slow cool allows a tiny amount of water to remain, which, seals the bag then after it is sealed the further cooling of the spawn causes a vacuum and seals and evaporates the rest of the water on the bag.

    I believe the key here is flash evaporation. Open quick and it will flash evaporate the moisture on the bag or actually in between the two pieces of plastic of the bag where it should seal.

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    Re: Cant get collapsed bags by end of pc cycle [Re: SHROOMSISAY01]
        #25580677 -

    I'd guess if all your contams are coming in through the top there might be an issue with your seal. Are you using an impulse sealer? If so are you keeping it closed for an extra 5-10 seconds after you hear the click? If not Id put my money on that being your issue.

      Ive also had difficulties with inflating bags - especially sawdust bags - in the PC. I've solved this problem- and the problem of them occasionally melting - by wrapping them in a towel. I can only fit 2 6lbs bags at a time anyway so that extra space isnt wasted.


    --------------------





    Indoor Greenhouse Build 
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    Re: Cant get collapsed bags by end of pc cycle [Re: TravelAgency]
        #25580680 -

    also are you using .2 mycron filter patches? .5 is too big for grain spawn but can be ok for sawdust.


    --------------------





    Indoor Greenhouse Build 
              Mid Size Mushroom Farm

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    Re: Cant get collapsed bags by end of pc cycle [Re: TravelAgency]
        #25580769 -

    TravelAgency said:
    also are you using .2 mycron filter patches? .5 is too big for grain spawn but can be ok for sawdust.


    I have no idea, I will check with manufacturer, you think if the pore size is too big the graion bags will contaminate anyway?

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    Re: Cant get collapsed bags by end of pc cycle [Re: TravelAgency]
        #25580772 -

    TravelAgency said:
    I'd guess if all your contams are coming in through the top there might be an issue with your seal. Are you using an impulse sealer? If so are you keeping it closed for an extra 5-10 seconds after you hear the click? If not Id put my money on that being your issue.

      Ive also had difficulties with inflating bags - especially sawdust bags - in the PC. I've solved this problem- and the problem of them occasionally melting - by wrapping them in a towel. I can only fit 2 6lbs bags at a time anyway so that extra space isnt wasted.


    Sometimes I use an impulse sealer, sometimes I dont, I dont like mine very much. At any rate, RR says he closes his bags with just electrical wire (which I do sometimes), never uses an impulse sealer, and gets away with it.

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    Re: Cant get collapsed bags by end of pc cycle [Re: vsoares]
        #25580789 -

    Yes they sure will. I dont know any commercial producers that use any larger than .2 for grain spawn. I know MorePies toyed with it a little bit, maybe he will chime in.


    --------------------





    Indoor Greenhouse Build 
              Mid Size Mushroom Farm

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    Re: Cant get collapsed bags by end of pc cycle [Re: SHROOMSISAY01]
        #25580807 -

    SHROOMSISAY01 said:
    Sorry I will be a little more careful with my jokes next time. I actually know nothing about thermal dynamics and I actually had to look up how to spell it. What I do know is from experience. I have never opened up my PC quickly but every time I open my 55-gallon steamer right after a cycle is done my top bags are loose but. If I wait for a day or two they are all sealed perfectly. The OP mentioned equalizing the pressure so I assume he is releasing the pressure which is his problem.

    What I believe is happening when you release quickly is the bag cools down much quicker than the spawn and evaporates any water on the plastic and never seals. When you let it cool down slowly it slowly pulls the bag together and does not evaporate the moisture between the two pieces of plastic the slow cool allows a tiny amount of water to remain, which, seals the bag then after it is sealed the further cooling of the spawn causes a vacuum and seals and evaporates the rest of the water on the bag.

    I believe the key here is flash evaporation. Open quick and it will flash evaporate the moisture on the bag or actually in between the two pieces of plastic of the bag where it should seal.


    Because my autoclave pulls a vacuum by the end of the cycle, I have to equalize the pressure before opening it, by releasing the valve, otherwise the pressure differential will keep the lid shut.

    Actually I am a physicist myself (but never worked in the area), and as far as I understand, what happens is this:

    1) In the beginning, there is "atmospheric" air inside of the pc, just like outside.

    2) As the pc is heated, the pressure inside it increases, forcing the air out, which is the same as saying that the air density (number of molecules of O2, N2 etc per unit volume) inside it is reduced. Because the vent valve is open, the pressure differential is always very small, as the the air keeps being released from the pc chamber.

    3) When we reach the boiling point of water, H2O molecules start coming out the the liquid phase at a fast rate, filling the pc chamber and, at the same time, pushing the O2, N2 etc molecules out of the pc, further reducing the density of gases inside the chamber.

    4) If we leave the valve open for long enough, allowing the steam plus air mixture to vent abundantly, there will be very little gas molecules left inside the autoclave, which will be mostly filled with steam.

    5) We then proceed to close the vent valve, and as the chamber is further heated, more steam comes out of the liquid phase, increasing the pressure inside the chamber.

    6) The pressure raises to the point where the pressure differential between the inside and the outside of the chamber is balanced by the weight at the top of the air vent hole. At this point, the system is in some sort of equilibrium, the temperature is stabilized, and the pressure inside the chamber is basically constant.

    *) During steps 2-6, because the heating up of the air inside the bags is slower then the heating up of the air inside the pc, there is a pressure differential between the inside of the chamber and the inside of the bags, which forces the air from the bags out, helping reducing the ammount of gas molecules inside the bags.

    7) At the end of the cycle, he pc starts cooling of, and the pressure inside the chamber falls. At this point we have basically steam filling the chamber, and the reduction in temperature means that some of those molecules will return to the liquid phase (reducing the pressure), wherever they happen to be (inside the bags, for instance), and everything will get pretty wet. If the cooling off is too quick, there might be a significant pressure differential between the inside of the bags and the pc chamber itself, but now in the opposite direction that was seen during the heating up, which might cause the bags to inflate (instead of collapsing further).

    8) Because we have so little gas molecules inside the pc, when we return to room temperature, the pressure inside the chamber will be smaller then outside (if the pc is completely sealed, which is the same as to say, "pulls a vacuum"). If the pc does not pull a vacuum, then air will seep inside the chamber gradually as the pc is cooled. If the inflow of air is slow (which will happen if the cool down is very gradual), then the gases will fill the chamber, but might not be able to get inside the bags. The bags will keep "collapsed".

    As I understand, the bags get collapsed during the heat up phase. During the cool down, they might inflate back or not, depending on what you do, but I dont think they collapse during that part of the cycle.

    An important point to make here, if I did not myself so clear, is that what makes the bags shrink (or inflate) is the pressure differential between the inside of the bag and the inside of the pc chamber, and not the difference in pressure between the inside of the chamber and the outside of the pc (atmospherc pressure). So in fact our system actually has 3 "chambers": the outside of the pc, the inside of the pc (and outside of the bags), and the inside of the bags.

    So as I see it, opening the vent valve at the end of the cycle has no possible benefit, and it might screw everything up by letting the bags inflate. In theory I suppose thats what happens. I guess I will try putting some weights on top the bags to see if the extra pressure will help the bags to deflate further during the heating up (and also, make it harder for them to inflate back during the cool down).

    Edited by vsoares (10/31/18 06:52 AM)

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    Re: Cant get collapsed bags by end of pc cycle [Re: TravelAgency]
        #25580849 -

    TravelAgency said:
    Yes they sure will. I dont know any commercial producers that use any larger than .2 for grain spawn. I know MorePies toyed with it a little bit, maybe he will chime in.


    Sure ppl use A patch bags for spawn.  It is better for mold bc more air means it will more likely sporeulate .  Then you can see it if it's there


    --------------------
    Fiery Fungi (like us on faeboo)

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    Re: Cant get collapsed bags by end of pc cycle [Re: drake89]
        #25580857 -

    drake89 said:
    TravelAgency said:
    Yes they sure will. I dont know any commercial producers that use any larger than .2 for grain spawn. I know MorePies toyed with it a little bit, maybe he will chime in.


    Sure ppl use A patch bags for spawn.  It is better for mold bc more air means it will more likely sporeulate .  Then you can see it if it's there


    I see people in Thailand use cotton plugs on top of their grain jars. I think people in the US also use cotton or polyfil plugs, dont they? Is a polyfil plug better than a 0.5 micron filter patch?!

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    Re: Cant get collapsed bags by end of pc cycle [Re: vsoares]
        #25580866 -

    In my opinion, yes- however this comes mostly from my understanding of other peoples experience not my own trials. I'd say its worth a shot if you can get just a clutch of bags - run them side by side to the ones you already have and see if thats the difference. And please share your results!


    --------------------





    Indoor Greenhouse Build 
              Mid Size Mushroom Farm

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    Re: Cant get collapsed bags by end of pc cycle [Re: vsoares]
        #25580874 -

    To further ellaborate on my analysis of the pc cycle:

    There is a diference if you vent the chamber or not at the end of the cycle. If you dont vent, there will be many more water molecules inside the chamber in the form of steam, which means things will get wetter as they cool down. On the contrary, if you do vent the chamber, there will be less steam to cool down, and you should get drier bags at the end of the cycle.

    Also, as my analysis indicates, if the valve is open after the chamber reaches 0 psi, there will be no more "bad" pressure diferential between the inside of the bags and the pc chamber, because the pc chamber will be always at atmospheric pressure (from that point on). If the bags are already "sealed" at this point (which means, if they are collapsed with bag sides "glued" to each other), and as the steam inside the bags cool down and the pressure inside them falls, there might be further tightening of them. If the bags are not sealed, though, air will just seep inside of them.

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    Re: Cant get collapsed bags by end of pc cycle [Re: vsoares]
        #25580891 -

    I'm still curious as to how you seal them before PCing? Do you use an impulse sealer?


    --------------------





    Indoor Greenhouse Build 
              Mid Size Mushroom Farm

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    Re: Cant get collapsed bags by end of pc cycle [Re: TravelAgency]
        #25580895 -

    TravelAgency said:
    I'm still curious as to how you seal them before PCing? Do you use an impulse sealer?


    I dont seal them at all before pcing. I just fold them over.

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    Re: Cant get collapsed bags by end of pc cycle [Re: vsoares]
        #25580961 -

    bingo. While presealing isnt necessary for sawdust bags, in my experience it is not wise to do so with grain, and this could also be your inflation problem. Do you seal after inoculation?


    --------------------





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    Re: Cant get collapsed bags by end of pc cycle [Re: TravelAgency]
        #25581119 -

    Yes sometimes I seal after inoculation, sometimes I just twist a piece of eletric wire on top of it. I think RR does the same and gets zero contams. He also doesnt seal bags prior to pcing.

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    Re: Cant get collapsed bags by end of pc cycle [Re: vsoares]
        #25581137 -

    RR, as amazing as he was - was 15+ years ago. After you inoculate, seal. Every single time. With your contams coming in through the top, forget everything else I've stated so far. Start sealing and see if your contams go away. I'd be willing to stake my reputation on that being your vector. If you already have an impulse sealer, theres no excuse not to use it. If you dont have one, save up 30 bucks and get one on ebay.The addition of that tool changed my game entirely. Speed, security, sanity - and no top fruiting were all pros with literally zer0 cons. Mycology isnt really suited to cutting corners.


    --------------------





    Indoor Greenhouse Build 
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    Re: Cant get collapsed bags by end of pc cycle [Re: TravelAgency]
        #25581610 -

    I use .5 micron on my spawn bags without a problem many people do. I do understand it is not recommended but it can and is done by many people.

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    Re: Cant get collapsed bags by end of pc cycle [Re: TravelAgency]
        #25581799 -

    TravelAgency said:
    RR, as amazing as he was - was 15+ years ago. After you inoculate, seal. Every single time. With your contams coming in through the top, forget everything else I've stated so far. Start sealing and see if your contams go away. I'd be willing to stake my reputation on that being your vector. If you already have an impulse sealer, theres no excuse not to use it. If you dont have one, save up 30 bucks and get one on ebay.The addition of that tool changed my game entirely. Speed, security, sanity - and no top fruiting were all pros with literally zer0 cons. Mycology isnt really suited to cutting corners.


    Ok, but you talked about pre-sealing the bags before pcing. Wont they explode? You seal the bag, pc, then cut the seal open, inoculate, and seal again?

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    Re: Cant get collapsed bags by end of pc cycle [Re: vsoares]
        #25581861 -

    No they won't explode. Yes exactly the method you describe,  push all air out when you seal prior to pc.


    --------------------

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    Re: Cant get collapsed bags by end of pc cycle [Re: Quadman]
        #25581987 -

    .2 micron is not meant to be sealed b4 PCing. But that does not mean you can't do it. If the bag bursts, it would be for that reason. .5 micron can be sealed b4 PCing with no problem. I use .5 micron with no problems for spawn and sub alike.

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    Re: Cant get collapsed bags by end of pc cycle [Re: SHROOMSISAY01]
        #25582026 -

    It's .2 if it looks like a paper patch. It's. 5 if it looks like the stuff in a bandaide.


    --------------------
    Stop talking about being enlighten. Crybabies, bitches, and people worried about ratings can never reach enlightenment!  NEVER!

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    Re: Cant get collapsed bags by end of pc cycle [Re: Quadman]
        #25582103 -

    I have yet to have a bag burst in the PC unless the bag was touching one of the lower regions of the autoclave.

    Quadman said:
    No they won't explode. Yes exactly the method you describe,  push all air out when you seal prior to pc.


    Yep, exactly as my good friend Quad said. How have you been buddy? :wave:

    Like I said, presealing is not necessary, but I wouldnt advise it. Especially in a PC - a Steam Sterilizer will be much more forgiving, but still wouldnt advise.

    But you must - must seal after inoculation.


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    Indoor Greenhouse Build 
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    Re: Cant get collapsed bags by end of pc cycle [Re: TravelAgency]
        #25582142 -

    Interesting discussion and great arguments and theories :cheers:

    However I still don't get from vsoares' hypothesis what the actual consequences are of slow cooling and pressure equalization / small pressure differential vs fast cooling and pressure equalization / large pressure differential.

    And also how the air might get into the bag reinflating it in some cases but not others.

    Shroomsisay's cool idea about the water playing a role in the seal created which could be that factor in whether air is allowed to get back in or not upon cooling.

    Now that I think about it, what may also play a role is how the plastic bag cools down. In my experience it retains the shape it got during PCing which is not surprising since you can get kinda close to melting range, probably enough for mild thermosetting.
    I say this because I tend to put my bag on a crushed can on the bottom of my PC to elevate it. I do have some elevated plateau to get above water level in my PC but it's not enough if I do a long PC cycle of wood and occasionally a shitload of water manages to escape compared to other times so i add enough.
    Point is: this shapes the bag bowed and this persists quite a bit.

    What compounds this is I don't really think you create a true sealed "vacuum" (i.e. underpressure), there is nothing suggesting to me when I open the bag for inoc that I break that seal after which the bag reinflates a bit like a popping lid of a jar. You would have to be seeing a moment when the seal breaks and there is a sudden rush of air entering.

    I hadn't heard earlier about you equalizing the pressure of the autoclave like that (i thought you didnt use the valve and just let it equalize gradually.. and I still don't think you have mentioned how much time you allow to pass before you do open up the autoclave.

    So I guess I do agree with the suggestion earlier that this is where it goes wrong, that you don't leave enough time for cooling (could take annoyingly long with an autoclave?) and that the pressure equalization is too fast perhaps. Is there no way to do it incrementally? If so I would do it as incrementally as possible.

    Some gusts of air entering is one thing but if the bag reinflates too and sucks up the gusts of air that could be the big problem indeed. You may need to improvise some way to either avoid the sudden changes in temp and pressure and if not, protect your bags from the air rushing in somehow.

    Is there no way to make sure that the air getting back in the autoclave is sanitized? Or could it be fitted with a custom valve (safely of course!) to slow down the air current?

    I guess i underestimated the general importance of taking it a bit slow after a PC cycle and that my situation probably is much faster (but still gradual) in the equalization so i don't get these problems I guess. So you're right shrooms

    Shroomsisay actually in hindsight it is kinda funny how i missed the joke (thats what happens without nonverbal communication or emojis haha) and went into the physics.

    I only recently started sealing after inoc of bags, remembering that i have a ghetto vacuum sealer... other times I just do two small folds at the top and put on clothespins. Occasionally a little tape to make sure it stays that way. Definitely will only seal from now on if i can trust the sealer to seal the deal.

    I don't know how you are using that electrical wire, but it would have to be pretty terribly to get consistent contams on top while i am fine with the folds and clothespins.

    But yea if i get to the point of tumbling my bags to mix like Gr0wer then you can bet your baby's beehive that I will be sealing the bag :wink:


    --------------------
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    • Edited by Solipsis (10/31/18 04:29 PM)

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    Re: Cant get collapsed bags by end of pc cycle [Re: Solipsis]
        #25582362 -

    Hey TA:hi:

    I should add a disclaimer,  I've never sealed .2 micron bags and PC them .

    There is an aspect that is often overlooked. Everyone lives in different regions and different structures. My 100 year plus old home is a mold magnet. Couple that with living in the Midwest and it seems a recipe for disaster. I will always seal my bags when cooking. A 941AA autoclave is what is my main method.

    OP stated that he draws a vacuum. If opening while under vacuum, would suggest  filtering the intake valve with alcohol rag.

    I've had decent results watching the cool down and as soon as cooker has cooled to zero pressure ,opening valve. This prevents a large in rush of air (and contaminates). Still does not keep sterile .

    Best to just open at flow hood if it pulls vacuum.:shrug:


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    Re: Cant get collapsed bags by end of pc cycle [Re: Quadman]
        #25582377 -

    They make in line hepa filters


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    Fiery Fungi (like us on faeboo)

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    Re: Cant get collapsed bags by end of pc cycle [Re: Quadman]
        #25583494 -

    Man I have to say I am really lost. I see people doing what I consider much more contamination-prone procedures than me, and still get away with it. The last 4 grain spawn batches I've made were 100% contaminated, and I sealed 90% of the bags after inoculation.

    I let the autoclave cool down for at least 24 hours. I simply turn of the power (its electric) by the end of the cycle, and walk away. After 24 to 30 hours it will be around room temp (if it is not too crowded), and what I do is put 2 pieces of micropore tape in the vent hole (I have also tried a microbiological filter disk, mounted to be used with syringes), and open the valve ever so slightly, so the air seeps in very slowly (it takes maybe 5 to 10 minutes to get the pressure back to atmospheric). Then I open the autoclave, transfer the bags immediately my flow hood (the autoclave is literally in front of the flowhood, so I dont even have to walk to make the transfer). Still I am getting 100% contamination, sometimes green mold, sometimes black mold. Unfortunately I think I will have to go back to doing grain spawn in glass jars, because I need the grains and cant make any using bags...

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    Re: Cant get collapsed bags by end of pc cycle [Re: vsoares]
        #25583499 -



    This video shows very clearly what I mean by collapsed/airtight bags. I have never gotten anything even remotely like this.

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    Re: Cant get collapsed bags by end of pc cycle [Re: vsoares]
        #25583724 -

    Try agar and check your spawn That is where the problem must lie. I guess if you go back to jars and you still have the problem you will know also. Once you figure it out don't leave us hanging let us know what the problem was, please.

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    Re: Cant get collapsed bags by end of pc cycle [Re: SHROOMSISAY01]
        #25583870 -

    Yeah your problem doesn't lie in the autoclave,  more than likely


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    Re: Cant get collapsed bags by end of pc cycle [Re: drake89]
        #25584918 -

    Collapsed bags aside, you went from jars to bags? Sounds like that is when contaminates started? How big are the grain bags and how long at 15 psi?


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    Re: Cant get collapsed bags by end of pc cycle [Re: Quadman]
        #25585538 -

    How would bad spawn acutely cause bags not to go vacuum?

    That aside: yes if you get consistent contaminations of course double check if your spawn is clean with agar. It is certainly possible to have contams not really show up yet until that point but hitching a ride invisibly, but it would have to be invisibly contaminated with at least 2 types of mold....

    I would have to re-read the thread but do bags which are left unused to check also contaminate or do only the bags contaminate which you inoculate after autoclaving? Obviously the problem is not in your autoclave if you only get contamination with inoculated bags.
    But if you get contamination on just the grain itself, no inoculation, after doing nothing at all with the bag after it comes out of the autoclave then I don't see how the problem could not be in either the bags or the autoclave or the procedures involved with only that stage of work since those are the only factors involved in what should result in a sterilized bag.


    --------------------
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  • Fungi - Edible / Gourmet
  • Fungi - Medicinal/Insecticides/Bioluminescents
  • Fungi - Actives
  • Fungi - Old Exotic Spores (Actives)
  • Fungi - Misc Hunted Mushroom Spores
  • Plants
  • Other items - Supplies etc.


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    Re: Cant get collapsed bags by end of pc cycle [Re: Solipsis]
        #25586193 -

    Yeah you need to do a control batch to start narrowing down your vector of contamination.  That means run a batch thru your autoclave, and seal them without inoculation and see if anything grows.  If it does, well, that sucks.


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    Fiery Fungi (like us on faeboo)

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    Re: Cant get collapsed bags by end of pc cycle [Re: drake89]
        #26203538 -

    Hi guys, sorry for not giving any feedback here, but after much experimenting, I found out some things that I would like to post here to keep registered.

    First, the reason I was getting so many contaminated grain bags was that I was using the wrong patch filters for grains. I now realize thats a somewhat basic thing, but I didnt know the importance of that then. So what I did was buy bags with filters with much smaller pore size (made specifically for grain spawning, that is), and now I get much less contaminated bags.

    Another problem I had was that I was cramming my little autoclave with too many bags at the same time, and that means I had to steam for a bit longer to get adequate sterilization. So now I let the bags sterilize for at least 2 1/2 hours at full pressure, and my contamination count has decreased even further.

    Lastly, I found out what has to be done to make the bags become airtight (sturdy like bricks) at the end of the sterilization cycle. What happens is that, if the bag is put inside the autoclave without any object (like another bag, or some sort of weight) on top of it, it simply wont become airtight the way I wanted. So what makes the block "vacuum sealed" is putting some kind of weight on top of it.

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    Re: Cant get collapsed bags by end of pc cycle [Re: vsoares]
        #26210451 -

    I dont put anything on my bags. When your pc reaches 15 psi you need to vent out steam to ~10 psi to suck air out of the bag. Then you let it get to 15 psi again and do your cycle. The bags will look like they were vacuum sealed.


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