How much Attenuation is possible.....

If your yeast states 85% attenuation, how much can you really have? 97% seems impossible. I did the calculations according to whitelabs. (attenuation = [(OG-FG)/(OG-1)] x 100. Is this right and is 100% attenuation possible?

I don't think so and I'm rechecking my gravities. OG 1.084 FG 1.000 and .998. Wyeast 1214 and an Allagash Tripel cultured yeast.
Grain:
24lbs Belg Pils
1lbs Belg Bisc
1lbs Belg Aromatic
2lbs Inverted table sugar
2lbs table sugar(both added 10 min end of boil)
Mashed at 148 for about 70min

my calc was 100% and 102%

apparent attenuation and real attenuation are different things.

http://www.realbeer.com/spencer/attenuation.html

how do you have two final gravities?

I'm not sure how you have different FGs, but table sugar and corn sugar are 100% fermentable, and alcohol has a lower gravity than water so it's possible to have an apparent attenuation that is very high.

For my wines, I routinely get .990 as a FG.

I brewed a 10g batch and split it pitching two separate yeast in two 5g carboys. I figured the sugars a lot to do with it, but I figured the yeast would reach a certain point and just die off leaving me with a FG of around 1.010 - 1.005. Maybe I'm not understanding this too well.

I wouldn't be surprised if those were inaccurate measurements. Yes, it's possible to go below 1.000 for non-beer. But it seems unlikely that you'd get that low.

low mash temp, lots of sugar

sudndeth said:

I brewed a 10g batch and split it pitching two separate yeast in two 5g carboys. I figured the sugars a lot to do with it, but I figured the yeast would reach a certain point and just die off leaving me with a FG of around 1.010 - 1.005. Maybe I'm not understanding this too well.

Click to expand...

Well, the yeast don't die off- they're still alive but just dormant when the fermentable sugars are gone. In most beers, that's usually 1.008-1.016 or so. But in a beer with fermentable simple sugars, you could get lower. A low mash temp also creates a more fermentable wort (more easily fermentable sugars vs. long chained sugars). With a recipe with 4 pounds of simple sugars, and mashed at 148, it would be possible to get a low FG and a super dry beer.

The maximum possible real attenuation is 100%. The maximum possible apparent attenuation is higher.

Wort fermentability is a much larger factor than yeast selection. The range of attenuation quoted for yeast is apparently assuming a wort typical for the style the yeast might be used for. If all yeast were tested on a standard wort you would find that they do not very much in terms of terminal gravity.