I promised I would keep you nformed, so here goes;
2 weeks after my first post, the sg had not moved, so I decided to rack the beer with the yeast cake, to get the yeast back in suspension. That really worked. Yet another 2 weeks later, the sg had dropped to 1.025, and I decided it was time to separate the beer from the yeast and get it bottled. I will post the final recipe & notes below here , as they explain the process the way things were done in the end. The beer is certainly drinkable today, full body, rich with lots of coffee, but there's still an off flavour to the taste, higher alcohol, sulfury notes, almost like a boiled egg type of taste hidden in the background. Still I don't regret having seen it through, so thanks for all advice for keeping it. Here's the final recipe with notes;
Style: Imperial Stout
Batch size: 17.0 l
Boil volume: 27.0 l
Bitterness (IBU): 96.0
Color (SRM): 33.8
5.00 kg Maris Otter Malt, 76.9%
0.45 kg Flaked Oats, toasted, 6.9%
0.40 kg Crystal 50-60L (British), 6.2%
0.40 kg Crystal 40L, 6.2%
0.15 kg Chocolate Malt (British), 2.3%
0.10 kg Black Barley, 1.5%
50.00 g First Gold (AA 8.3%, Pellet) 60 min, 56.2 IBU
70.00 g Styrian Golding (AA 5.2%, Whole) 30 min, 34.1 IBU
50.00 g Fuggles (AA 4.2%, Pellet) 5 min, 5.7 IBU
Coffe, Coursely ground, 1.0 unit(s), Flavor On bottle day, Home Rosted 150 gram coffe beans to dark french roast, milled coarsely, poured into french press and let degas for some hours, poured 500ml water, 80°C over the crushed beans, let it "warm extract" a few hours while stirring the grains into suspension now and again. Used result coffee to dissolve bottling sugar, kept at 80 degrees during 30 minutes. Boiling 10 minutes would probably have been safer, but would kill the aroma.
Danstar Windsor, 2.0 unit(s), Yeast I pitched on slurry from a previous brew. Otherwise, use two 11g.packets of yeast (total 22 grams).
Irish Moss, 1.0 unit(s), Fining , boil 15 min
How to toast flaked oats (havregryn) in your oven: On a cookie sheet, spread out and toast 500g. (yes, start out with 500g.) flaked oats in oven at 160°C for 90 minutes, turning the oats around and re-spreading them every 15 minutes, increase temperature to 180°C the last 15 minutes. I used 2 trays with cookie sheets in the oven with convection fan turning. When your kitchen starts smelling like a cookie factory, you know you're on the right track, and you can relax with a homebrew. Water will evaporate from the oats during the toasting, and you'll be left with about 450 grams, toasted, brown oats at the end, and as miraculous as it may sound, that's exactly what you need for this recipe. Now how cool is that! Store it dry and high for brewday, and toss it in the mash with the rest of your grain bill. Mash at 67°C for about 90 minutes. Boil 90 minutes, and follow the hop schedule. Add irish moss at 15 minutes as you hook up your wort chiller.
Brewday, 11 aug. 2012. Mashed at 68°C with 21 liters water, mash tun full with those quantities. After first run-off added 11.5 liters at 95°C, made 78°C in mash tun. Collected 27 liters, way too much. Cut back water. Boiled vigorously until about 22 liters (1hour), then added bittering hops. Collected 17 liters in fermenter, OG=1.080, too low.= 65% efficiency. Pitched on Windsor slurry from porter, Aerating with pump for about 1 hour. Fermentation started after about 6 hours and fermented vigorously for about 20 hours, then it slowed down, 24 hour later, no more activity. 13 august, about 42 hours after ferment start, SG=1.032. Hopefully it will go down some more. Next time, such high gravity brew needs lower mash temp, and use high attenuation yeast strain, such as nottingham. 2 weeks later, still1.032 so racked with all the slurry to re-suspend it. Sept 02, SG=1.029. Sept 06, SG=1.025. Sept 9, Bottle day, see coffee notes above.