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Foil on starter

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gromet

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I've seen in a video posted on this forum that you should use aluminum foil instead of an airlock when making a yeast starter so as to allow air in. I have just made my first starter and covered it with foil. How tight should I wrap it? It seems like unless you just laid it on there it would keep air out as well. Also it would seem that in order to prevent contamination it would need to be on there pretty tight. Thoughts?
 

KingKegII

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I put a square of foil on big enough to cover the opening with about an inch or 2 overlap, then I just bend the excess down over the sides of the opening and mold the foil to the neck of the flask. This keeps the foil on tight enough so it won't fall off, keeps floating wild yeast and bacteria out, and still allows oxygen in. Even 'hand tight', the gaps between the foil and the glass are still big enough to allow oxygen/air in.
 

LVBen

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You can use aluminum foil or an airlock. If you use aluminum foil, you should wrap it tight enough to form a good seal that allows a very small amount of CO2 to escape, but not so tight that the only way CO2 could escape is by the pressure ripping a hole in the foil.
 

JNye

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I've heard the theory it that is gas is leaving, gas is coming in.
 
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gromet

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I've heard the theory it that is gas is leaving, gas is coming in.
That would make sense. Barometric pressure would have to equalize in the absence of a perfect seal.

Thanks for the advice all!
 

LVBen

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That would make sense. Barometric pressure would have to equalize in the absence of a perfect seal.

Thanks for the advice all!
CO2 production causes the pressure to increase... so it equalizes with the release of the CO2, which is why we put foil on the starter instead of capping it.
 

JNye

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While the yeast is processing sugar, there is ideally more CO2 escaping than anything getting in.
Yes but its still certainly better then having a check valve on the vessel which guarantees no oxygen being introduced. Besides, in question is tight foil, or loose foil, the difference is immaterial, if gas can flow, gas will flow. Ideally you would be shaking or using a stirplate along with the foil. I simply shake/swirl as often as I remember and do so with the foil OFF.
 

balzern

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I always put a small square of sanitized foil on my starters. Seems to work well while it is cooling in an ice bath. I put a foam stopper in my flasks to allow the wort/yeast to breathe.
 

camus

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Whao, wait a minute. The whole purpose of a starter is to produce more yeast, yeast need O2 to reproduce.

Just cut a square that adequately covers the opening, don't use an airlock, you want the CO2 to be replaced with O2.

Loosely cover with aluminum foil, no rubber bands etc. Just 'crimp' it.
 

balzern

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Whao, wait a minute. The whole purpose of a starter is to produce more yeast, yeast need O2 to reproduce.

Just cut a square that adequately covers the opening, don't use an airlock, you want the CO2 to be replaced with O2.

Loosely cover with aluminum foil, no rubber bands etc. Just 'crimp' it.
or a foam stopper.
 
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gromet

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Well, after 48 hours and re-pitching in to a new starter, absolutely no change from OG 0f 1.041. I assume this means my yeast is dead.
 

JNye

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to me yes, sounds dead. I'm sure others will tell you wait 72 hours, but starters generally get moving pretty quickly for me, and i don't have time to wait another day when it comes to starters.
 

Wiezer

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Well, after 48 hours and re-pitching in to a new starter, absolutely no change from OG 0f 1.041. I assume this means my yeast is dead.
What temp was the starter at when you pitched your yeast?
 

jangelj

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previously i used a piece of foil on my starter, and left it much looser than you all are describing. never had an infection. this past week i made a starter and used a paper towel sprayed with starsan held in place by a rubber band.

figured anything going in would hit the starsan, and the paper towel would allow plenty of oxygen to come thru. seemed to work fine, too.
 

bovineblitz

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previously i used a piece of foil on my starter, and left it much looser than you all are describing. never had an infection. this past week i made a starter and used a paper towel sprayed with starsan held in place by a rubber band.

figured anything going in would hit the starsan, and the paper towel would allow plenty of oxygen to come thru. seemed to work fine, too.
I used to do that, then one time I had an acetobacter infection in a starter and found a fruit fly in there... so... I crimp the foil down now.
 
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