Yeast Toupee: too much Irish Moss?

[clumsy]

For the consideration of my fellow brewers…

The beer on the left was brewed January 1, 2015. The beer on the right was brewed January 3, 2015. The one on the left has what I'm calling a "yeast toupee", bits of krausen that have formed a sort of a lid over the beer. The beer on the right looks like what I expect: the krausen has sunk to the bottom.

These aren't the same recipe, but I'm suspecting that the main difference between these two beers is that I used three times as much Irish moss on the one to the left: one tablespoon for the last twenty minutes of the boil, vs. one teaspoon for the last ten minutes in the beer to the right.

I've seen this once before: that time I used a tablespoon of Irish Moss too. That beer tasted just fine, but it looked pretty disgusting in the fermentor.

So… does anyone know if this is what happens when you use too much Irish Moss? Or is this something else entirely?

[maltyapples]

What was the starting specific gravity of the beer on the left? I found that my higher SG beers formed a krausen more readily (but given that I don't brew tons and tons of beer, that could be circumstantial). If you're using different yeast strains for each beer that could also be it. Cheers!

[clumsy]

As I recall, the beer on the left started at 1.039, the other at 1.055. I didn't even think about gravity, thanks for the tip!

[maltyapples]

Hearing numbers like that make me think there is more at work than SG for krausen formation. Perhaps it has something to do with protein formation in different beers?

(After some reading)

According to John Palmer, the krausen is a combination of yeast, proteins, and other insoluble components in the beer. Green spot formations are proteins, dead yeast, and hop residue. Avoid stirring the krausen back into your beer as this will result in a harsh taste. The components of the krausen are by and large insoluble, so effects from stirring are hardly ever a problem.

Well, that was enlightening for me. It's certainly time for me to reread the good old homebrewing bible.

[clumsy]

I bottled the beer on the left today: I'm calling it "Tragic Toupee". I generally let beers sit on the yeast for a month, but I was getting sick of looking at it.

It actually tasted pretty good at bottling, but it started low and finished high: 1.039 => 1.015. I was playing with a new mash schedule, and it didn't work out that well. I'm planning to let the beer on the right sit for another week at least before I bottle it.

[Mikegobrew]

Is it the same yeast? Looks to me like the one on the left is just a highly flocculant yeast. It probably wont attenuate as much and will be very clear like you filtered it.

[clumsy]

Is it the same yeast?

It is the same yeast. I'm still baffled by it, but they're both in bottles now.

The one on the left is actually drinkable at this point, but it's a little too bitter for its weight. The one on the right's only been in the bottle for a week: I haven't opened one yet.

[corkybstewart]

I doubt the moss had anything to do with the difference. I never measure Irish moss, I just scoop some out and toss it in the kettle and I've never seen any visible difference.