Ale yeast on top?

[Richlandbrewer]

I originally posted this in the AG forum and got 56 looks but no replies so I guess I need to resort to the yeast experts on this forum

So I have been doing AG (strictly ales, 5 gallon batches) for many years, fermenting in the standard 6 gallon plastic buckets. My experience is that when I open the fermenter up (after a week or more), the top surface is more or less beer, with some yeast islands floating around, which quickly migrate to the perimeter and stick to the side of the bucket as I drain it into the bottling bucket.
Recently I got a chance to obtain a stainless steel vessel with a shallow cone bottom that is about 15" in diameter as opposed to my plastic buckets which are slightly less than 12" dia. So the "aspect ratio" of the stn. stl. fermenter is much different than the plastic bucket, with the wort mass being "shorter" than it is tall.
Anyway, I have used this (the stn. stl vessel) for fermenting, using ale yeast (normally Safale 05, same as I would use in a bucket batch) and I end up with a significant layer of yeast (residue?)on top after fermentation is complete (I confirm this with an FG check, and it is good). The layer I am describing is not active - it has kind-of a glossy top and is easily skimmed off. And I have in fact skimmed it off prior to draining it into the bottling bucket. The beer is good, but I am mystified about the difference between the two approaches and would really appreciate any insight as to why there is such a difference between the yeast sitting on top versus settling to the bottom.

 

[schokie]

Do you always use the same yeast? I find different strains flocculate differently, similar to the ways you describe.

But I can't imagine why different shaped fermenting vessels would cause that.

 

[Richlandbrewer]

Yes, I have done this 3 times now with the same yeast (Safale 05) that I use in the bucket. It's perplexing. One thing - the top on the stn stl one does not fit tight enough such that the gas can escape through the lid "seal" easier than through an airlock, so although I still put on an airlock, it doesn't bubble. The rim of the top has a turn-down and my sanitation is thorough so I am not worried about contamination. Hard to imagine that playing a role, but I just don't know.

 

[cjgenever]

Glossy is usually an indication of bacteria. Are there any fittings, welds, or even possible microscopic pits in the ss that could harbor bacteria?