Clarification strata

[AsharaDayne]

One thing I've noticed since I've started using glass carboys is that the brew sometimes clarifies in strata. It's particularly obvious in a cider I've got going now, it really has several equal layers of increasing opacity, but I've also seen it in some beers. Interesting phenomenon, I wonder what that's all about.

 

[jeffpn]

Gravity, I imagine. You're talking from the top down, right?

 

[jmcnamara]

I think the heavier bigger bits would fall first. Followed by smaller particles and dead yeast. Then any other yeast if you cold crash

 

[Mase]

I've seen this as well. It doesn't appear to be suspended grain or hops.

 

[J A]

I've noticed a pretty distince delineation as it clears, too. If the temp is cold enough it happens almost overnight and the process isn't observable, but in one of my fridges the temp isn't as cold and it takes 2-3 days to drop. It's easy to see the clear part make it's way deeper into the carboy. One thing that makes the difference seem more dramatic is that the light from the fridge bulb is shining from above and illuminates things more at the top layers. The difference isn't a stark when I shine a flashlight through the side.

 

[Nosybear]

Glass or plastic shouldn't make a difference in how fast stuff settles. I notice this more in wine than in beer but you're right, there is a "top-down" effect, should be expected because particles are different sizes, bigger (and heavier) ones settle out first. The lighter particles will stay in suspension longer and are likely still in the process of "sticking" to one another, becoming heavier and settling. We've used Isinglass frequently to drop the particles out of wine. Gelatin works well for beer and is cheap. But in any case, you'll see stratification as the finings work - simple physics, a small particle stays in suspension longer than a big one.

 

[jeffpn]

Glass or plastic shouldn't make a difference in how fast stuff settles.

He means now that he's using glass, he can see it happening!

 

[Nosybear]

He means now that he's using glass, he can see it happening!

Wasn't clear - but if he was using an opaque container before, you're right. Explanation of why still stands: Brownian motion - the effect that keeps the particles in suspension - works much better on smaller particles.

 

[jeffpn]

Wasn't clear

Exactly. That's why he could see it!

I went with "gravity."

 

[AsharaDayne]

OK, to clarify (no pun intended), yes, I got some opaque plastic containers first, then was given some 1gal glass carboys, which are a bit of a pain, but do have the advantage in aesthetic terms and in letting me watch the brew as it evolves.

I'm more or less aware of how clarification happens. I'm just curious about that layer effect - I would have been less surprised if it just made a continuous gradient.