Besides the obvious grist composition/mash temp/yeast strain, how else can we control attenuation?
Numerous times I've brewed some of Ron Pattinson's recipes, and have ended up with a lower than expected final gravity.
Consider a recent stout I brewed, ended up with a FG of around 1.004, down from an OG of 1.041. Grist used was:
36.4% Irish Stout Malt
14.4% Fawcett Optic Malt
14.4% Golden Promise Malt
7.6% Rahr 2-row Pale Malt
8.4% Black Patent Malt
5.8% Brown Malt
6.3% Invert No. 1 (Lyle's Golden Syrup)
6.6% Black Invert (Lyle's Golden Syrup mixed with Blackstrap Molasses)
Yeast was Wyeast 1469, from a shaken not stirred starter. Mash temps were between 152-150 for 90 minutes.
The recipe I based this beer on can be found here:http://barclayperkins.blogspot.nl/2013/11/lets-brew-wednesday-1923-courage-stout.html
Kristen England's version notes a FG of 1.011, with an apparent attenuation of 74%. I ended up with 90%. FWIW, Wyeast lists the attenuation for this strain as being between 67-71%. I don't see modern malt being the culprit here, as Kristen's version should have had the same issue. Any other ideas?