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FreeSporePrints

Registered: 03/06/05
Posts: 1,139
Loc: Rome, Italy
Last seen: 1 month, 27 days
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Excess of agar - Steam in petris
#5892749 - 07/23/06 11:10 PM (17 years, 6 months ago) |
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i create this thread here cause i'm not able to post in "Agar" subsection (perhaps i live too much in the Gourmet section) ^_^
-1st question:
If i use a bigger amount of agar for the broth recipe this can let troubles for the growth of the mycelium(example a low pH etc etc)??
-2nd question:
i've a lot of steam into my GLASS petris, i use to put them with the lid little opened in the oven at 160°C until the steam dissapear, but when i take them from the oven in 5 minutes the steam re-appear. Perhaps have i to let stay them in the oven until they reach the environmental temperature? can you also suggest me your tips?
Really thank you
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liamtheloser
Advanced Idiot

Registered: 06/07/06
Posts: 1,453
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this has nothing to do with your agar question... but i'm trippin and your post looked like it said "excess of agro- stream of penis"
hahaaaa
sorry
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creamcorn
mad scientist


Registered: 03/13/06
Posts: 2,962
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stack them, and take a coffee cup filled with hot water and put it on the top one. that way the warmer temp from above prevents anything from condensing on the lid... let them all cool in a stack like that and you'll have nice clear petris.
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FreeSporePrints

Registered: 03/06/05
Posts: 1,139
Loc: Rome, Italy
Last seen: 1 month, 27 days
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Re: Excess of agar - Steam in petris [Re: creamcorn]
#5892779 - 07/23/06 11:25 PM (17 years, 6 months ago) |
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liamtheloser: your're welcome 
creamcorn: yes i've tryed it, i used to fill the coffe cup with the hot water of the PC, but seems me to do not work. Perhaps because my petri aren't made by plastic, but glass??
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liamtheloser
Advanced Idiot

Registered: 06/07/06
Posts: 1,453
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ever tried letting them cool off with the oven? ie. leaving them in the oven til the oven is completely cool? might not apply to petris, but i know that if i leave my jars in the PC until it's completely cool there's no condensation on the sides...
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creamcorn
mad scientist


Registered: 03/13/06
Posts: 2,962
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could be. glass is a good insulator, so maybe the warmth from the ones above doesn't transfer to the ones beneath so well. don't know, have only dealt with the disposable plastic ones...
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fastfred
Old Hand



Registered: 05/17/04
Posts: 6,899
Loc: Dark side of the moon
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Re: Excess of agar - Steam in petris [Re: creamcorn]
#5893042 - 07/24/06 12:38 AM (17 years, 6 months ago) |
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1. No. You should only need to use 20g/L of agar though. If you add too much it becomes almost like plastic.
2. You'll get the same steam problem with plastic petris also. You should pur your petri's in a stack when pouring. That way only the top one should have a steam/condensation problem. To get rid of condensation just put them on a warm surface top down for awhile and the water will evaporate away and either condense on the agar or be wicked away into the air.
-FF
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FreeSporePrints

Registered: 03/06/05
Posts: 1,139
Loc: Rome, Italy
Last seen: 1 month, 27 days
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Re: Excess of agar - Steam in petris [Re: fastfred]
#5893531 - 07/24/06 04:35 AM (17 years, 6 months ago) |
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liamtheloser: no i should try, but unlucky i use a mini oven where there's just the space of 2 petris.
fastfred: about 2nd answer, if i put them top down without open a little the lid the water will remain into the petris, and "unlucky" the water evaporate from down to up condensing on the agar surface.
..and water on agar surface is a good vector for bacterias!
Thank you.
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RogerRabbit
Bans for Pleasure


Registered: 03/26/03
Posts: 42,214
Loc: Seattle
Last seen: 11 months, 3 days
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If you had them open in the oven, they're going to be contaminated anyway so start over.
Wait until your agar is cool enough to pour without protection for your hands from the heat. If you pour the agar while it's too hot, you'll get lots of condensation. If you're going to put the dishes in the oven, so so before your pour. That way, there won't be a temperature differential between inside and outside and condensation will be reduced.
Keep the dishes in a vertical stack at all times. Within a couple of days, the condensation will be re-absorbed back into the agar.
In my experience, glass petri dishes are not suitable for mycology due to the large number of dishes you need to conduct experiments. They're also heavy and slippery when handled with gloves that are wet with alcohol, not to mention the trouble you go through cleaning and sterilizing them. You can get a box of 500 pre-sterilized plastic petri dishes for the same price as 20 glass ones and they're far superior for our purposes. RR
-------------------- Download Let's Grow Mushrooms semper in excretia sumus solim profundum variat "I've never had a failed experiment. I've only discovered 10,000 methods which do not work." Thomas Edison
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