sage_bd said:

yeah they are cheap, but they're the most popular ones on Amazon though so I'd venture to guess most folks don't have Pyrex.

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LewDoja said:

Just becarful Thurman just posted about pre pour petris and had some issues.

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bluespirit13 said:

Okay so I need to post the results from a test today.  I did some agar (no pour) and did pasty plates (glad mini rounds) and jelly jars (4oz jars fitted with filter lids) sterilized In the same batch and the results really speak for themselves. Jelly jars are no moisture and pasty plates are MOIST! 

Jellies






Pasties





Open to criticism and suggestions but in the future I see myself using jelly jars for no pours. Mostly plan to use Brf pucks anyways but for agar, why use something that has so much moisture?

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Quote:

ThurmanMurman said:
Agar bubbled up and spilled over enough to stick lids to plates, so much condensation in the vessels holding the plates that water actually got between the plates, creating suction that needed two hands to slide a plate off the stack while I was working. There was probably agar in there too which helped with the stickiness, idk.

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I've had the suction issue with the plates I linked to above, but because they're screw top that isn't an issue, just use rubber tongs (bbq grill type) and a towel. If you've got 8-15g of agar in the plates they won't have the bubbling issue either.

Condensation is an issue though. What I did with my last batch that seems to be good enough for me is the following:

• Pre-pour the agar into the plates.
  
• Close the plates but leave them a quarter turn open so the steam can get in during the PC cycle.
  
• I use a trivet that is flat with holes in it (not a wire one) to keep them level in the PC.
  
• I can fit 33 in my 8qt instant pot, 7 stacks of 5 minus 2 where the vent is.
  
• I vent for 10 min and PC for 45 min.
  

So right after the PC cycle I vent the PC and do the following on a towel because they're still kinda wet after taking them out of the PC:

• I get them all out with the rubber bbq tongs (twist them closed as you're taking them out & dry them).
  
• Make stacks 6 high
  
• Flip the stack while the agar is still hot.
  
• I roll them on the table to get the sides first.
  
• Then move the agar around on the lids (the stack is upside down now) to mix the condensation on the lids back into the agar, this also warms the lids so they'll from less condensation later.
  
• Flip the stack right side up.
  
• Tilt the stack (so the agar can run back down the sides) and tap them on the table to get the agar off the tops (most of the agar does actually come off see the pics below).
  
• I leave them stacked until they solidify, then flip them once the agar is solid so that any condensation that is left is on the bottom (I think this is pretty standard for plate storage)
  
• Storage: you can fit 32 of these in a standard 6qt shoe box
  

You are left with some strands of agar on the tops which isn't the best for taking pictures etc but it gets rid of most of the condensation which I worry about more since it gives contams a way to move around.

I just did this again the other day and had the same results so it should work if you follow those instructions.

Note I use this LME agar recipe 300mLs gets me ~30 plates (they're thin):

• 1.5g LME
  
• 6g agar
  
• 300mL
  

Which might play a factor in how clean the tops are after doing this silly flip & mix nonsense. I'd do 12-15mL per plate if you want to free pour them and not have to worry about getting the right amount per plate, you can always test with water to see how thin you have to pour on a scale for reference (1g = 1mL). I microwave my media bottles to boil the agar with the cap on loose so it can vent. If you do this definitely don't leave it unattended just watch it for the 3 min or so it will take to boil, then seal it and shake it until everything is dissolved. Bubbles won't matter during the pre-pour because you're going to PC them anyway.

This is what they look like at room temp ~68F


and this is how they look in my agar incubator (tub in tub with fish tank heater) ~80F




Here is another set for reference, notice the agar streaks/spots on the top row, these aren't in my incubator so that's the only reason they have condensation on them and are hazy still. Also, notice the top right and the one below it, the drops of agar that were in the center dry out and fade to be pretty negligible (those two plates were in my incubator).


I think they work and look alright

A Note regarding the 'defective lids' (called out in Alien's tek):
If you do get these PP5 twist top containers the spec on the lids is a little loose. The containers will all pair with their lid, but some lids will be too small for other containers so I try to keep them all as pairs the best I can when cleaning etc. This is relatively easy because the lids fit over the containers when upside down really well. If you don't do this you *might* get stuck playing a stupid game of which lid goes on which container when trying to put all the caps back on. But for ~$0.48 ($24 per 50x) each and infinite reuse I think its worth the hassle vs I pay ~$4 for 50 condiment cups so 300x 2oz cups for the same price.

So the solution I've found is I try to keep them paired with their mate when cleaning by keeping the lid on the container, the container fits in the lid upside-down so its not that hard to keep track of, I mention it in my little write-up of how I use them. So basically when you're cleaning them you take off the lid and put it under the container and then you wash them like that keeping them together, until you pour them and I pour them now with the lid underneath its respective container so you don't have the play the dumb matching game.

Acknowledgements & Other Agar teks I've found useful:
Alien's Holy Grail No pour Agar unmodified containers. Same PP5 twist tops
ReverendMyc's Primo Plates: Reusable Clear Plastic Petri Plate Prepour tek
fiddle_head's Sauce Like a Boss: A Visual Guide
D3's Perfect Agar
+ the obvious agar teks that everyone links to bod/pastey/milkboy/tiger drop etc.

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Thanks for All the Fish